long term performance of portland limestone cement concrete

Cairo – 2011

Ain Shams University Faculty of Engineering

Structural Engineering Department

LONG TERM PERFORMANCE OF PORTLAND LIMESTONE CEMENT

CONCRETE

By Jehan Mahmoud Ali Elsamni

B.Sc. 1998 Civil Engineering Department

Ain Shams University

Thesis Submitted in partial fulfillment of therequirements of the degree of

MASTER OF SCIENCE in

Civil Engineering

Supervised by Prof .Dr . Salah A. Abo-El- Enein

(D.Sc) Professor of Physical Chemistry and Building Materials

Faculty of Science, Ain Shams University

Dr . Ahmed Fathy Abdel-Aziz Associate Professor

Structural Engineering Department, Faculty of Engineering, Ain Shams University

Dr . Hany Mohamed Elshafie Associate Professor

Structural Engineering Department, Faculty of Engineering, Ain Shams University

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STATEMENT

This thesis is submitted to Ain Shams University, Cairo, Egypt, in

partial fulfillment of the requirements for the degree of Master of Science

in Civil Engineering.

The work included in this thesis was carried out by the author at

properties and testing of Materials lab of the faculty of engineering, Ain

Shams University.

No part of this thesis has been submitted for a degree or

qualification at any other university or institute.

Date : / / 2011

Name : Jehan Mahmoud Ali Elsamni

Signature : Jehan Elsamni

To my father, You are always remembered and greatly missed

ACKNOWLEDGMENT

All praise be to Allah Subhanahu wa ta’ala for bestowing me with health,

opportunity, patience, and knowledge to complete this research. May the

peace and blessings of Allah Subhanahu wa ta’aala be upon Prophet

Mohammed (Sala allahu alaihi wa sallam).

I would like to thank my parents, brothers and sister for their constant

prayers, guidance, encouragement and support throughout my career.

They are the source of power, inspiration, and confidence in me.

Acknowledgement is due to Faculty of Engineering, Ain Shams

University for the support given to this research through its facilities and

for granting me the opportunity to pursue my graduate studies.

I acknowledge, with deep gratitude and appreciation, the inspiration,

encouragement, and continuous support given to me by Dr. Ahmed Fathy

Abdel-Aziz working with him was an opportunity of great learning and

experience.

Thereafter, I am deeply indebted and grateful to Dr. Hany Mohamed

Elshafie for his extensive guidance, continuous support, and personal

involvement in all phases of this research.

I am also grateful to Prof. Dr. Salah A. Abo-El-Enein for his guidance,

technical support and suggestions during the research.

Thanks are due to the personnel of properties and testing of material

laboratory, faculty of engineering, Ain Shams university, especially Mr.

Nabeel Mostafa, Mr. Emad Elsayed, Mr. Shreef Elsayed for their

substantial assistance in the experimental work.

Ain Shams University Faculty of Engineering

Structural Engineering Department

Abstract of M.Sc. Thesis submitted by: Jehan Mahmoud Ali

Elsamni

Title: “LONG TERM PERFORMANCE OF PORTLAND

LIMESTONE CEMENT CONCRETE “

Supervisors:

1. Prof .Dr . Salah A. Abo-El- Enein

2. Dr . Ahmed Fathy Abdel-Aziz

3. Dr . Hany Mohamed Elshafie

ABSTRACT

New edition of the Egyptian Standard Specifications 4756-

1/2005, for different types of cement has been issued recently following

the European Specification EN 197-1/2004 for common cements. These

specifications contain different categories of cements including Portland

blended cements (Designated by CEM II) which compose mainly of

Ordinary Portland Cement (OPC) with a percentage varies from 65 to 94

% and pozzolanic materials or inert fillers with a percentage varies from

6 to 35%. One of the popular types of the Portland blended cement is

Portland Limestone Cement (PLC) where Ordinary Portland Cement is

blended with finely grounded limestone which is considered as

chemically inert filler. Blending of limestone powder with OPC has

beneficial effect on reducing the amount of energy needed for

manufacturing the cement and consequently reducing the cement cost

and producing more environmental friendly cement. The limestone

powder is inert and does not add to the cement strength, however,

owing to its physical properties, it has some advantages on the concrete

properties including workability, capillarity, bleeding, and cracking

tendency. Compared to OPC concrete, the PLC concrete may have

comparable short term strength, but its strength development with time

under different exposure conditions and long term performance need to

be addressed.

Based on the new specifications, many of the local cement

manufacturers have been producing PLC. Properties of these types of

cement depend on the manufacturing method and composition of

limestone which changes from one location to another. As a new type of

cement in the local market, it has not to be used in producing concrete

before evaluating the long term performance of the concrete. Therefore,

this research has been initiated to study the long term performance and

high temperature resistance of the concrete produced by Portland

limestone cement. The main variables to be covered in the current study

include cement and limestone contents and exposure conditions. The

long term characteristics of the concrete to be considered are strength

development under different exposure conditions, resistance to sulfate

attack and reinforcing steel corrosion, and high temperature resistance.

From the analysis and discussion of the test results obtained in the

current research, it is concluded that for the same cement content and

water/cement ratio the compressive strength for PLC concrete is less

than that of OPC concrete and the reduction in compressive strength is

proportional to the limestone content. However, to attain comparable

compressive strength with OPC concrete, PLC concrete should contain

higher cement content and lower water/cement ratio. It is concluded that

if the compressive strengths of both PLC and OPC concretes are

comparable, PLC concrete is as good as OPC in both short and long term

characteristics. On the other hand, compared to OPC concrete, PLC

concrete has lower drying shrinkage and comparable high temperature

resistance. Therefore, it is concluded that PLC can be used in producing

plain and reinforced concrete provided that the cement content and

water/ cement ratio are modified to achieve the specified compressive

strength.

Keywords : Compressive Strength, Corrosion Resistance, Drying

Shrinkage, Pozzolanic materials, Durability, Long Term Performance,

Fly Ash, Silica Fume, Ordinary Portland Cement (OPC), Portland

Limestone Cement (PLC), Sulfate Attack and Fire Resistance.

i

TABLE OF CONTACTS

Page

CHAPTER 1: INTRODUCTION 1

1.1 Background……………………………………… 1

1.2 Organization of the present work………………… 2

CHAPTER 2: LITERATURE REVIEW 3

2.1. Introduction……………………………………… 3

2.2 History of using limestone with Portland cement

all over the world…………………………………….. 3

2.3 Hydration and Setting…………………………… 10

2.3.1 Chemistry………………………………… 10

2.3.2 Analysis of composition………………… 13

2.3.3 Heat evolution …………………………… 21

2.3.4 Microstructure………………………..…… 22

2.3.5 Setting time…………………………..…… 23

2.4 Fresh mortar and concrete………………..……… 26

2.4.1 Particle Size Distribution………………..… 26

2.4.1.1 Comminution…………………..… 26

2.4.1.2 Workability of paste, mortar, and

concrete………………………………...

30

2.5 Hardened Mortar and Concrete…………………… 35

2.5.1 Mechanical properties…………………… 35

2.5.1.1Strength and Strength Development 35

2.5.1.2 Volume Stability………………… 50

2.5.2 Durability………………………………… 54

2.5.2.1 Permeability……………………… 54

2.5.2.2 Carbonation……………………… 58

2.5.2.3 Freeze/Thaw and Deicer Scaling… 64

2.5.2.4 Sulfate Resistance……………… 69

2.5.2.5. Thaumasite ……………………

80

ii

Page

2.5.2.6 Chlorides………………………… 85

2.5.2.7Alkali-Silica Reactivity…………... 88

2.5.2.8 Corrosion………………………… 89

2.5.3 Interactions with mineral and chemical

admixtures .............................................................

92

2.6 Specifying and Monitoring Quality………………. 94

2.6.1 Limestone………………………………… 94

2.6.2 Cement with limestone…………………… 98

2.6.3 Concrete…………………………………… 101

2.7 Needed Research………………………………… 102

CHAPTER 3: RESEARCH PROGRAM

3.1 Introduction……………………………………….. 103

3.2 Scope ……………………………………………. 103

3.3 Objectives……………………………………….... 103

3.4 Variables considered…………………………… 104

3.5. Mix proportions………………………………… 104

3.6 Properties considered…………………………… 104

CHAPTER 4: MATERIALS USED AND TESTING

PROCEDURES

4.1 Introduction……………………………………… 108

4.2 Properties of Materials Used…………………… 108

4.2.1 Fine Aggregate…………………………… 108

4.2.2 Coarse Aggregate………………………… 109

4.2.3 Cementitious Material…………………… 109

4.2.3.1 Cement………………………… 109

4.2.3.2 Fly Ash………………………… 113

4.2.3.3 Silica Fume …………………… 113

4.2.4 Admixtures………………………………. 113

4.2.4.1 High Range Water Reducer ……

113

iii

Page

4.2.5 Reinforcing Steel bars…………………….. 114

4.2.6 Materials used to prevent steel bars from

corrosion………………………………….……

114

4.2.6.1 Epoxy zinc coat………………… 114

4.3 Testing procedures………………..……………… 114

4.3.1 Compressive strength test ……………….. 114

4.3.2 Accelerated corrosion test. .……………… 114

4.3.3Sulfate resistance………………………… 117

4.3.3.1 Sulfate resistance of concrete

exposed to sulfate solution……………

117

4.3.3.2 Potential Expansion of cement

mortar exposed to sulfate………………

117

4.3.4 High temperature resistance……………… 118

CHAPTER 5: TEST RESULTS AND ANALYSIS

5.1 Introduction………………………………………. 119

5.2 Compressive Strength and strength gaining……… 119

5.2.1 Effect of limestone content on strength and

strength gaining…………………………………

121

5.3 Accelerated Corrosion test ……………………… 126

5.3.1 Corrosion Current………………………… 126

5.3.2 Mass Loss ………………………………… 127

5.3.3 Crack patterns…………………………… 129

5.3.4 Effect of limestone content on corrosion

resistance...............................................................

129

5.4 Sulfate resistance…………………………………. 133

5.4.1 Sulfate resistance of concrete cubes ……… 133

5.4.1.1 Limestone content effect on

Sulfate resistance of concrete cubes ……

137

5.4.2 Sulfate resistance of cement mortar

exposed to sulfate (Potential Expansion) ……….

137

iv

Page

5.4.2.1 Effect of Limestone content on

Sulfate resistance of cement mortar

exposed to sulfate (Potential Expansion)

138

5.5 High temperature resistance……………………… 139

5.5.1 Influence of limestone content on high

temperature resistance ………………………

142

5.6 The effect of cement and limestone contents on the

compressive strength of concrete mixes……………....

144

CHAPTER 6: SUMMARY AND CONCLUSIONS

6.1 Summary………………………………………… 152

6.2 Conclusions……………………………………… 153

6.2.1Conclusions regarding compressive strength 154

6.2.2Conclusions regarding corrosion resistance.. 155

6.2.3 Conclusions regarding sulfate resistance for

concrete cubes and linear expansion of mortars.... 157

6.2.4 Conclusions regarding heat resistance..........

157

REFERENCES …………….…………..……………………

158

APPENDICES

Appendix A....………………………………………… 173

Appendix B....………………………………………… 176

Appendix C....………………………………………… 178

v

LIST OF FIGURES

Page

CHAPTER 2: LITERATURE REVIEW

2.1 Portland limestone cement market share in

Germany……………………………………………….

8

2.2 Pozzolanic cement market share in

Italy…………………………………………………….

9

2.3 XRD patterns of PEC pastes (1: ettringite, 2: calcium

monosulfate hydrate, 3: Portlandite (C–H), 4:

gismondine2 (CaAl2Si2O8.4H2O), 5: quartz, 6:

anhydrous compounds of clinker)……………………

19

2.4 XRD patterns of PLC pastes (1: ettringite, 2:

monocarboaluminate hydrate, 3: Ca–Al–Si hydrate)…

20

2.5 XRD patterns of composite cement pastes at 7 days

(1:ettringite, 2: calcium monosulfate hydrate, 3:

monocarboaluminatehydrate, 4: Ca–Al–Si hydrate)…..

20

2.6 Cumulative mass distributions of a Portland limestone

cement with a limestone content of 12% by mass, as

well as of the two individual constituent materials after

intergrinding in an industrial ball mill (after Schiller

and Ellerbrock, 1992)………………………………….

28

2.7 Effect of heat curing on the compressive strength of

concretes made with and without limestone. “Test A”

contains 4.1% limestone and “Test B” contains 2.3%

limestone (after Bédard and Bergeron, 1990)…………

38

2.8 Strength development of cements……………………..

41

vi

Page

2.9 The ratio of compressive strengths for mortars made

with Portland cements with up to 6% limestone to that

of companion samples made with Portland cement

without added limestone. The dashed line connects the

mean values at each age. The data represent 374 sets of

samples from 11 sources (Bobrowski et al. 1977;

Bayles 1985; Crawford 1980; Combe and Beaudoin,

1979; Hawkins 1986; Hooton 1990; Klieger 1985;

Livesey 1993; Lane 1985; Matkovic et al. 1981; and

Tsivilis et al. 1999)……………………………………

44

2.10 The ratio of compressive strengths for concrete made

with Portland cement with limestone to that of

companion samples made with Portland cement

without limestone. The dashed line connects the mean

values at each age. The data represent 491 sets of

samples from 10 sources (Bayles 1985; Bedard and

Bergeron, 1990; Bobrowski et al. 1977; Detwiler 1996;

Hawkins 1986; Klieger 1985; Livesey 1993; Matkovic

et al. 1981; Nehdi et al. 1996; and Suderman

1985)…………………………………………………...

46

2.11 The ratio of compressive strengths for mortars made





samples from 4 sources with cement C3A contents less

than 8% (Bobrowski et al. 1977, Hawkins 1986,

Livesey 1993, and Tsivilis et al. 1999)………………

47

vii

Page

2.12 The ratio of compressive strengths for concretes made





samples from 5 sources with cement C3A contents less

than 8% (Bobrowski et al. 1977, Hawkins 1986,

Livesey 1993, Nehdi et al. 1996, and Suderman

1985)…………………………………………………...

48

2.13 The ratio of flexural strengths for mortars made with

Portland cement with limestone to that of companion

samples made with Portland cement without limestone.

The dashed line connects the mean values at each age.

The data represent 59 sets of samples from 3 sources

(Combe and Baudouin, 1979; Livesey 1993; and

Matkovic et al.1981)…………………………………...

49

2.14 The ratio of flexural strengths for concrete made with



The dashed line connects the mean values at each age.

The data represent 15 sets of samples from 1 source

(Matkovic et al. 1981)…………………………………

50

2.15 Permeability coefficient of concretes made with

Portland cement (PZ) and Portland limestone cement

(PKZ) containing 13 to 17% limestone and subjected

to different curing regimes……………………………

56

viii

Page

2.16 Carbonation of concretes made from different cements

and exposed to 20°C, 65% R.H. for three years. Water:

cement ratios were between 0.60 and 0.65 and the

cement content was between 280 and 300 kg/m3.

Limestone content of PKZ 35 was 13% to 17%

(adapted from Schmidt et al. 1993)……………………

59

2.17 Specimen's shape and dimensions (corrosion tests)….. 63

2.18 Effect of type of limestone on frost resistance of

concrete. Portland limestone cements of class 32.5

were produced from the same clinker, but with

different types of limestone in amounts of 13% to

17%. In most cases the frost resistance is comparable

to that of the Portland cement (after Schmidt et al.

1993)…………………………………………………

67

2.19 Results of “cube” tests for the frost resistance of

concrete. Mass loss of less than 10% is considered

acceptable. Here the Portland limestone cements, PKZ

35 F (with limestone contents of 13% to 17%),

performed better than the companion Portland

cements, PZ 35 F (adapted from Schmidt et al.

1993)………………………………………………......

68

2.20 Expansion in test method ASTM C 1012 (after Taylor

2001a) for Type II cements with two levels of two

different limestones……………………………………

75

2.21 Expansion in test methods ASTM C 452 (after Taylor

2001a) for Type II cements with two levels of two

different limestones…………………………………....

75

2.22 Expansion in test method ASTM C 1012 test for

cements with C3A contents of 5% or less. Cements A3

and B3 were interground with 3% limestone (after

Taylor 2001b)…………………………………………

76

ix

Page

2.23 Expansion in test method ASTM C 452 for cements

with C3A contents of 5% or less. Cements A3 and B3

were interground with 3% limestone (after Taylor

2001b)………………………………………………….

76

2.24 Comparison of reduction in compressive strength in

the mortar specimens exposed to varying

concentrations of sodium solution for 24

months…………………………………………………

79

2.25 Specimens cured for 11 months in a 1.8% MgSO4

solution, at 5 oC………………………………………..

84

2.26 Specimens cured for 11 months in a 1.8% MgSO4

solution, at 25 oC……………………………………….

84

2.27 Effect of curing temperature on the compressive

strength of the specimens……………………………..

85

2.28 Corrosion potential vs. exposure time and limestone

content………………………………………………….

91

2.29 The effect of the limestone content on the mass loss of

rebars…………………………………………………..

91

2.30 Required water: cement ratio to achieve a slump of 60

to 70 mm in concretes made with different cements.

Cement E contained a limestone not conforming to the

EN 197-1 criteria. Comparison of the water: cement

ratios for 0% and 5% limestone contents shows that the

poor quality limestone did not affect the water demand

for the 5% limestone cement, but had a deleterious

effect on the water demand when the limestone content

exceeded 16% (after Brookbanks 1993)………………

97


PROCEDURES

4.1 Schematic figure of Lollipop Specimen……………… 115

4.2 Schematic figure of the Accelerated Corrosion Cell… 116

x

Page

4.3 Accelerated corrosion Cell…………………………… 117

4.4 Mould of expansion specimen………………………. 118

4.5 Expansion specimen apparatus……………………….. 118

4.6 High temperature oven……………………………….

118


5.1 Compressive strength of the various concrete mixtures

up to curing ages of 540 days………………………..

120

5.2 Compressive strength for concrete mixtures made of

cements containing 0, 15% and 25% limestone with

cement content (Cc) 300, 350 and 400 kg/m3,

respectively, at 3days………………………………...

122




respectively, at 7 days………………………………..

122




respectively, at 28 days……………………………….

123




respectively, at 56 days……………………………..

123




respectively, at 91 days……………………………….

124

xi

Page




respectively, at 365 days……………………………

124




respectively, at 540 days……………………………...

125

5.9 Corrosion time for different concrete mixes………….. 126

5.10 The mass loss for rebar in concrete specimens…….. 128

5.11 Typical crack pattern………………………………… 129

5.12 Corrosion time and compressive strength of concrete

made of PLC vs. limestone content for mixes……….

129

5.13 Corrosion potential vs. time for mixtures having

compressive strength 20-25 MPa……………………...

121

5.14 Mass loss of rebars for mixes having compressive

strength 20-25 MPa………………………………….

132

5.15 Reduction in compressive strength of concrete

specimens exposed to sulfate solution for 12 months

136

5.16 Weight loss of concrete specimens exposed to sulfate

solution for 12 months………………………………

136

5.17 Concrete specimen C 11 exposed to 5% sulfate

solution for 12 months……………………………….

137

5.18 Linear expansion percentage of mortar prisms for

different types of cement…………………………….

138

5.19 The reduction in compressive strength after exposure

of concrete specimens to thermal treatment at 400

and 600°C for 3 hours and tested after 0 hours in

room temperature……………………………………..

141

xii

Page

5.20 The reduction in compressive strength after exposure

of concrete specimens to thermal treatment at 400

and 600°C for 3 hours and tested after 24 hours in

room temperature…………………………………...

141

5.21 The reduction in compressive strength of concrete

specimens after thermal treatment at 400o C and testing

after 0 hours……………………………………………

142



after 24 hours…………………………………………..

143



after 0 hours…………………………………. ………..

143



after 24 hours…………………………………………..

144

5.25 The relation between compressive strength of concrete

and Water/Cement ratio for the concrete specimens

made from different types after 7days of curing…….

147


and Water/Cement ratio for the concrete specimens

made from different types after 28days of curing…….

148


and cement content for the concrete specimens made

from different types after 7 days of curing…………

149


and cement content for the concrete specimens made

from different types after 28 days of curing…………

150

xiii

Page

CHAPTER 6: SUMMARY AND CONCLUSION

6.1 Reduction in compressive strength for PLC concrete as

percentage of OPC concrete (cement content 300, 350,

400 kg/m3)………………………………………

155

xiv

LIST OF TABLES

Page

CHAPTER 2: LITERATURE REVIEW

2.1 EN 197-1 permitted compositions of four Portland

limestone cements……………………………………..

6

2.2 CEM II market share of EU member

countries………………………………………………

7

2.3 Typical Limestone Compositions and Apparent Bogue

Compositions…………………………………………

16

2.4 Effect of Limestone1 on Average2 Type II and Type IV

Cements’ Bogue………………………………………

17

2.5 Average characteristics of Portland cements (Gebhardt

1995)…………………………………………………...

18

2.6 Ca(OH)2 content in pastes hydrated for 28 days ……. 21

2.7 Vicat Setting Times for ASTM and CSA Cements

(Hooton 1990)…………………………………….......

24

2.8 Vicat Setting Times for Interground Cements at

Constant Blaine (Hawkins 1986)………………………

25

2.9 Vicat Setting Times for Interground Cements at

Constant <325 Mesh (Hawkins 1986)…………………

25

2.10 Use of Limestone Substitution to Reduce False Set

(Gilmore) (Bobrowski et al. 1977)……………………

25

2.11 Water:Cement Ratio to Achieve 60-mm Slump

(Brookbanks 1993)……………………………………

33

2.12 Bleeding of Fresh Concrete, kg bleed water/m3

concrete (Albeck and Sutej, 1991)……………………

34

2.13 Average Bleeding Characteristics for Concretes With

and Without 5% Limestone in Cement (Brookbanks

1993)………………………………………………….

35

2.14 ASTM C 109 Mortar Cube Strengths, MPa (Hooton

1990)…………………………………………………

36

xv

Page

2.15 Average Strengths and Standard Deviations for

Cements Produced at Mergelstetten Plant January

1989 – May 1990, MPa (Albeck and Sutej, 1991)……

36

2.16 Strengths of Cements at “Constant” Blaine, MPa

(Hawkins 1986)………………………………………..

37

2.17 Strengths of Cements for “Constant” < 325 Mesh,

MPa (Hawkins 1986)…………………………………

39

2.18 Compressive Strengths for Concretes Made With

Cements With and Without Limestone, MPa (Bédard

and Bergeron, 1990)…………………………………..

39

2.19 Chemical composition of materials (%)………………. 42

2.20 Mineralogical composition (%) and moduli of clinker.. 42

2.21 Characteristic properties of the cements……………… 42

2.22 Summary Statistics for the Compressive Strength

Ratio Data……………………………………………...

45

2.23 Effect of Blended Limestone on Type II Cement, 6.4%

C3A, 400 m2/kg (Adams and Race, 1990)…………….

51

2.24 Effect of Blended Limestone on Type I Cement,

11.4% C3A, 339 m2/kg (Adams and Race,

1990)…………………………………………………...

52

2.25 ASTM C 151 Autoclave Expansions, % (Hooton

1990)…………………………………………………...

52

2.26 Drying Shrinkage of Concretes (Detwiler 1996)……… 53

2.27 One-Year Drying Shrinkage (UNI Standard 6555*) of

Concretes Made With Cements With or Without 20%

Limestone (Alunno-Rosseti and Curcio, 1997)……….

53

2.28 shrinkage/expansion of the samples………………….. 54

2.29 Water Absorption (UNI Standard 7699*) of Concretes

Made With Cements With or Without 20% Limestone

(Alunno-Rosseti and Curcio, 1997)……………………

57

xvi

Page

2.30 Carbonation Depths at 90 days and 1 year, mm (Barker

and Matthews, 1994)…………………………………..

60

2.31 Carbonation Depths (UNI Standard 9944*) at 900 days

in Concretes Made With Cements With or Without

20% Limestone (Alunno-Rosseti and Curcio, 1997)…

61

2.32 Characteristics of the tested cements…………………. 62

2.33 Concrete mix proportions and aggregate grading……. 63

2.34 Carbonation depth and total porosity of the cement

mortar………………………………………………….

64

2.35 Time to Cracking for Mortar Prisms Exposed to 5%

Na2SO4 (Soroka and Stern, 1976)……………………..

70

2.36 Time to Cracking for Mortar Prisms Exposed to 5%

Na2SO4 with 30% Filler, Weeks (Soroka and Setter,

1980)…………………………………………………..

71

2.37 ASTM C 1012: Time to 0.10% Expansion (Hooton

1990)…………………………………………………..

72

2.38 ASTM C 452 Expansions, % (Hooton 1990)………… 72

2.39 Sulfate Resistance in ASTM C 1012 Mortars

(Gonzáles and Irassar, 1998)…………………………

73

2.40 Composition and fineness of the cements used………. 82

2.41 Appearance of specimens, stored in 1.8% MgSO4

solution at 5 oC………………………………………...

83

2.42 Strengths of Mortars Exposed to Mixed Salt Solution,

MPa (Deja et al. 1991)……………………………….

87

2.43 Chloride Penetration (UNI Standard 7928*) of


Limestone (Alunno-Rosseti and Curcio, 1997)………..

88

2.44 Time to Cracking Due to ASR, Days (Hobbs 1983)…. 89

2.45 Compressive Strengths of Concretes, MPa (Detwiler

1996)…………………………………………………

93

2.46 Relative Strengths with Additive (Gartner 1996)……..

94

xvii

Page

2.47 Production Data for Cements With and Without

Limestone (Helinski 1996)…………………………….

100

CHAPTER 3: RESEARCH PROGRAM

3.1 The details of the different variables considered…… 106

3.2 Mix proportions…………………………………….. 107


PROCEDURES

4.1 Physical properties of sand…………………………. 108

4.2 Sieves Analysis for Fine Aggregate…………………. 108

4.3 Properties of Coarse Aggregate……………………… 109

4.4 Sieve Analysis for Coarse Aggregate………………… 109

4.5 Types of experimented used cements………………… 111

4.6 Physical properties of experimented cement………… 112

4.7 Mechanical properties of steel bars………………… 114


5.1 Compressive strength of the various concrete mixtures

up to curing ages of 540 days……………………….

121

5.2 The corrosion time for the concrete specimens………. 127

5.3 The mass loss for rebar in concrete specimens…… 128

5.4 Reduction in compressive strength of concrete

specimens exposed to sulfate solution for 12 months...

134

5.5 Weight loss of concrete specimens exposed to sulfate

solution for 12 months………………………………...

135

5.6 Linear expansion percentage of mortar prisms……….. 138

5.7 Reduction in compressive strength after thermal

treatment of concrete specimens at 600°C for 3

hours and tested at 0 and 24 hours…………………..

139

5.8 Reduction in compressive strength after thermal

treatment of concrete specimens at 600°C for 3 hours

and tested at 0 and 24 hours………………………….

140

xviii

Page

5.9 The details of cement mixes and the variables

considered...................................................................

145

5.10 The result of compressive strength at 7 and 28 days…

146

CHAPTER 6: SUMMARY AND CONCLUSION

6.1 Reduction in compressive strength for PLC concrete

as percentage of OPC concrete (cement content 300,

350, 400 kg/m3)………………………………………..

154

6.2 The mass loss for mixtures with strength 25MPa......... 156

xix

NOTATIONS

Esu The percentage of mortar expansion due to presence of SO3

F Faraday's constant

I Electrical current

m Mass of steel consumed by corrosion

M The atomic weight of metal

L2 The difference between the initial length of specimen and the

length of the calibration rod

L1 The difference between the length of specimen at 14 days and the

length of the calibration rod

L The difference between the effective length of specimen

Δt The time interval

Z The ionic charge

xx

ABBREVATIONS

AASHTO American Association of State Highway and

Transportation Officials

ACI American Concrete Institute

ASTM American Society for Testing and Materials

CEMBUREAU European Cement Association

CEN European Committee for Standardization

CSA Canadian Standards Association

DIN German Institute for Standardization “Deutsches Institut für Normung”

EN European Standards

I.R Insoluble Residue

ISO International Organization for Standardization

L.O.I Loss of Ignition

OPC Portland Cement

PLC Portland limestone cement

RRSB Rosin-Rammler-Sperling-Bennett

TGA Thermogravimetric Analysis

UNI Italian Organization for Standardization “Ente Nazionale Italiano di Unificazione “

XRD X-ray Diffraction

1

CHAPTER 1

INTRODUCTION

1.1 Background

The manufacture and use of Portland Limestone Cements (PLC) can bring economic benefits to both of the cement producer and user, and also considerable environmental advantages in terms of reduced CO2 emissions. In 2000, the EN 197-1 standard permitted constituent materials in pure limestone cements and recognized Portland composite cements. Concrete codes in some European countries restrict the use of PLC as durability and sulphate resistance varies, and their experience of the product is not as great as others. However, the opportunities and benefits that PLCs offer is likely to see their increased use in the next 10 years. The successful introduction of PLC requires that the necessary national standards and codes are in place and the recently adopted European Standard for Common Cements (EN 197-1) provides a template which many countries could follow to their advantage. Some countries in Europe have embraced the new opportunities created by the European Standard with enthusiasm and the tonnage of Portland limestone cement produced and used in these countries has increased markedly in recent years.

Locally, many of the cement manufacturers have been producing

PLC based on (EN 197-1) specifications, Properties of these types of cement depend on the manufacturing method and composition of limestone, which changes from one location to another. As a new type of cement in the local market, it has not to be used in producing concrete before evaluating the long- term performance of the concrete. Therefore, this research has been initiated to study the long - term performance and

Chapter 1 Introduction

2

high temperature resistance of the concrete produced by Portland limestone cement. The main variables to be covered in the current study include cement and limestone contents and exposure conditions. The long- term characteristics of the concrete to be considered are strength development under different exposure conditions, resistance to sulfate attack and reinforcing steel corrosion, and high temperature resistance.

1.2 Organization of the present work

This research work investigates the feasibility of using locally available Portland limestone cement in concrete. This research includes brief review of research into Portland cement interground or blended with limestone. Major topics covered include the effects of limestone use on the particle size distribution of the cement, including the effects on grinding and workability; the hydration and setting of the cement, including effects on reaction chemistry and kinetics, the Bogue calculation, heat evolution, microstructure, and setting time; the properties of mortars and concrete, including physical properties, durability, effects of mineral and chemical admixtures; and quality control aspects of the limestone, cement, and concrete. Research conducted all over the world over the past 20 years has been reviewed and summarized in chapter 2. Chapter 3 presents an overview for the research program. This chapter also include the details of test specimens, and test procedure. The properties of the materials used in the research work are introduced in chapter 4. Chapter 5 presents test results and analysis. Finally, the general conclusions of the study are given in Chapter 6.

Chapter 2 Literature Review

3

CHAPTER 2

LITERATURE REVIEW

2.1 Introduction

A summary of internationally issued researches from literature for

Portland cement interground or blended with limestone are reviewed.

Major topics covered include the effects of limestone use on the particle

size distribution of the cement, including the its effects on grinding and

workability; the hydration and setting of the cement, including effects on

reaction chemistry and kinetics, the Bogue calculation, heat evolution,

microstructure, and setting time; the properties of mortars and concrete,

including physical properties, durability, effects of mineral and chemical

admixtures; and quality control aspects of the limestone, cement, and

concrete. Emphasis has been placed on providing data from well-

documented sources from published literature and test reports from

laboratory studies. it was prepared to substantiate a proposed change to

ASTM C 150, “Standard Specification for Portland Cement,” to allow up

to 5% ground limestone in Portland cement. Limestone is currently being

used in cements produced throughout the world. Many researches which

have been conducted all over the world over the past 20 years has been

reviewed and summarized.

2.2 History of using limestone with Portland cement all over

the world

The use of up to 5% ground limestone in Portland cement has been

permitted by the Canadian “The product obtained by pulverizing clinker

consisting essentially of hydraulic calcium silicates to which calcium

sulphate, limestone, water, and processing additions may be added at the

option of the manufacturer”. Limestone is also provided for in the

European standard EN 197-1 (CEN 2000) which allows cements to


4

contain limestone in three different dosage levels. CEM cement standard

since the early 1980s. The CSA standard (CSA 1998) for Portland

cement, CAN/CSA-A5, defines Portland cement as: I, “Portland cement”,

may contain up to 5% minor additional constituents, of which limestone

is one possible material. CEM II/A-L and CEM II/B-L, both called

“Portland limestone cement,” contain 6% to 20% and 21% to 35%

ground limestone, respectively. Roughly 19% of all cement sold in

Europe contains between 6% and 35% limestone (CEMBUREAU 2001).

The requirements specified for limestone use pertain to effects on

performance only and will be discussed in Section (2.6.1) A review of

Cement Standards of the World (CEMBUREAU 1991) shows that more

than 25 countries allow the use of between 1% and 5% limestone in their

P “Portland” cements. Many countries also allow up to 35% replacement

in PB “Portland composite” cements. Since 1991, the latest edition of

Cement Standards of the World, several countries have modified their

standards to permit limestone in some amount, including Australia, Italy,

New Zealand, and the United Kingdom.

The manufacture and use of Portland limestone cements (PLC) can bring

economic benefits to both the cement producer and user and also

considerable environmental advantages in terms of reduced CO2

emissions. In 2000, the EN 197-1 standard permitted constituent

materials in pure limestone cements and alsorecognised Portland

composite cements. Concrete codes in some European countries restrict

the use of PLC as durability and sulphur resistance varies, and their

experience of the product is not as great as others. However, the

opportunities and benefits that PLCs offer is likely to see their increased

use in the next 10 years.

The successful introduction of PLC requires that the necessary national

standards and codes are in place and the recently adopted European

Standard for Common Cements (EN 197-1) provides a template which

many countries could follow to their advantage. Some countries in

Europe, notably Italy, Denmark, Sweden and Germany have embraced


5

the new opportunities created by the European Standard with enthusiasm

and the tonnage of Portland limestone cement produced and used in these

countries has increased markedly in recent years.

Finely divided limestone has been incorporated in masonry cements

produced in many countries for more than 50 years and is recognised to

have a beneficial influence on mortar plasticity and water retention

properties. The standardisation and use of Portland cements containing

limestone for concrete production was pioneered by Spain and France

during the 1970s and was motivated by the wish to reduce the energy

consumed in cement manufacture. The incorporation of up to 10 percent

limestone (or other non-harmful material) was permitted by Spanish

standards as early as 1960, but only for the lowest strength class of

cement. In 1975 the Spanish standards were revised to permit the

addition of up to 35 percent limestone to the lowest strength class. This

cement was not approved for structural reinforced concrete or concrete

exposed to aggressive conditions.

In 1979, France introduced a new standard which permitted the

incorporation of up to 35 percent of slag, fly ash, natural or artificial

pozzolana and limestone in a new type of cement designated CPJ. A key

feature of the new standard, which encouraged the utilisation of

limestone, was the introduction of four different strength classes with

upper as well as lower strength limits. Limestone could thus be used to

control the strength development of the lower strength class cements

whilst maintaining an appropriate level of cement fineness to ensure

satisfactory concrete rheological properties. After almost 30 years of

discussion, negotiation and compromise the first harmonized European

Standard under the Construction Products Directive, EN 197-1 Common

Cements, was formally adopted in 2000. This standard includes the

composition of all of the cement types with an established history of use

in the CEN member countries. Thus the permitted constituent materials

include well established materials such as blast furnace slag, fly ash and

natural pozzolana. Drawing on the successful experience with PLC


6

cements in France and Spain, limestone was also included as a permitted

constituent. Although not formally adopted until 2000, most European

countries revised their national standards in the early 90s to align closely

with the draft European Standard. For example BS 7583, Portland

limestone cement was published in 1992.

EN 197-1 includes 27 different types, four of which are Portland

limestone cements. The permitted compositions for these four cement

types are summarised in table (2-1).

Table (2-1): EN 197-1 permitted compositions of four Portland

limestone cements

Designation Limestone

%

Clinker % Organic carbon content of

limestone %

CEM II/A-L 6 - 20 80 - 94 ≤ 0.50

CEM II/A-LL* 6 - 20 80 - 94 ≤ 0.20

CEM II/B-L 21 - 35 65 - 79 ≤ 0.50

CEM II/B-LL* 21 - 35 65 - 79 ≤ 0.20

*The suffix –LL, rather than –L signifies a source of high purity limestone with a

particularly low content of organic material.

All limestone used to produce PLC must contain more than 75 per cent

CaCO3 and must also pass a test for maximum clay content which is

based upon the adsorption of methylene blue dye. The limits for organic

carbon content were introduced as a result of a research investigation in

the 1980s, which showed a possible connection between organic carbon

content and the freeze thaw performance of non airentrained concrete.

In addition to the above ‘pure’ PLCs, EN 197-1 also recognizes Portland

composite cements, which may contain up to 20 per cent (CEM II/A –

M) or between 21 per cent and 35 per cent (CEM II/B–M) of limestone

in combination with other constituents such as blast furnace slag or fly

ash. Cements of this type have a long history of successful use in France.


7

The addition of up to five per cent limestone as a minor additional

constituent is also permitted to all cements in the EN 197-1 family where

limestone is not already a main constituent.

In 2000, 24 per cent of the cement produced in European Union countries

was CEM II Portland limestone cement. This amounted to more than

40Mt of PLC. In 1999, the PLC proportion was 19 per cent. Data for

individual countries are given in table (2-2).

Table (2-2): CEM II market share of EU member countries

Country EU member country Cement

types

Plc market share %

2000*

Denmark II/A-L 46.2

France II/A-L II/A-LL

II/B-L II/B-LL 21.7

Germany II/A-LL 6.9

Italy II/A-L II/B-L 62.4

Spain II/A-L 21.2

Sweden II/A-LL 64.1

UK II/A-L ~1

* Data supplied by CEMBUREAU

The opportunities for increased PLC production and use created by the

new standards are illustrated by data for Germany as shown in Fig.(2-1).


8

Fig. (2-1): Portland limestone cement market share in Germany

Cement type: CEM/II/A-LL

The largest tonnage of PLC is currently produced in Italy (~24Mta).

Historical data for PLC production and consumption in Italy are not

readily obtainable as a result of changes in product type and designation

over the years.

However, the marked reduction in the production and use of pozzolanic

cement in Italy is largely accounted for by its displacement by PLC. Data

are illustrated in Figure (2-2).

A standard for PLC became available to Italian cement producers in 1993

and the cement was readily accepted by the Italian market as an

alternative to pozzolanic cement. Advantages included improved early

strengths and lower water demand.

0

1

2

3

4

5

6

7

8

9

10

1993 1994 1995 1996 1997 1998 1999 2000 2001

Year

PL

C m

ark

et s

har

e , %


9

Fig. (2-2): Pozzolanic cement market share in Italy

While several European countries have been very progressive in

introducing and using Portland limestone cements, countries outside

Europe have been slow to grasp the opportunities. A notable

exception is Thailand, which for many years has produced a ‘mixed’

cement which according to the national standard may contain up to 25

per cent limestone. As recently as 1998 ASTM Committee C 01 voted

down a proposal to permit the incorporation of up to five per cent

limestone in C 150 Portland cements. This was despite satisfactory

experience with limestone as ‘filler’ in neighbouring Canada for over 20

years. It is understood that ASTM have been asked to reconsider the

proposal. The European Standard EN 197-1, and the accompanying

conformity standard EN 197-2, has been circulated to the International

Standards Organisation Committee ISO/TC 74 and it is hoped that it will

be adopted as an ISO standard. This should accelerate its use as a

template for more progressive cement standards in countries around the

0

5

10

15

20

25

30

35

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001

Year

Poz

zola

nic

cem

ent

mar

ket

sh

are

, %


10

world. It must be recognised, however, that in countries such as the UK

and US, where the established practice is for addition materials, such as

blast furnace slag and fly ash, to be introduced at the concrete mixer, the

market acceptance of PLC cements is likely to be slower. Market

acceptance of PLC is also encouraged by the existence of clearly defined

strength classes in cement standards. Most European PLC cement is

produced as strength class (32.5).

The existence of strength classes has many advantages for cement users

and specifiers as cement performance is much more precisely defined

than is the case where only minimum strengths (often unrealistically low

and far removed from current levels of performance) must be met.

2.3 Hydration and Setting

2.3.1 Chemistry

Ingram et al. (1990) studied cement pastes made from various

proportions of Type I clinker, limestone, and gypsum and hydrated in

sealed vials for 1, 3, 7, 14, and 28 days. X-ray diffraction showed that for

a combination of 2% gypsum, 6% limestone, and 92% clinker, the

CaCO3 reacts with the C3A in the clinker. (Care was taken to avoid

exposing the pastes to atmospheric CO2.) They believe that the reaction

begins with a C3A.CaCO3.12H2O product which with continued

hydration forms compounds containing a molar ratio of C3A to CaCO3

between 0.5 and 0.25 At later stages, the product appears to stabilize as

C3A.X CaCO3.11H2O, where X ranges from 0.5 to 0.25 During the

course of this reaction ettringite formation proceeds normally.

Klemm and Adams (1990) studied the reaction of 5% or 15% calcium

carbonate (either as reagent grade CaCO3 or as ground limestone) and

Type II cement with hydration times up to one year. They found that

crystalline monocarboaluminate hydrate is slower to form than ettringite,

and after 129 days of hydration, 80% to 90% of the limestone or calcium

carbonate remains unreacted. They concluded that with Type II cements


11

limestone acts primarily as an inert diluent. Based on the solubility

products of the possible reaction phases, they predicted that the most

stable reaction phase would be ettringite, followed by

monocarboaluminate and then monosulfoaluminate.

Barker and Cory (1991) found monocarbonate forming in preference to

monosulfate. They also found that for cement with higher C3A contents

the amount of monocarbonate increases at all ages with increasing levels

of limestone as compared with cements having lower C3A contents.

Feldman et al. (1965) found that the hydration of 90% pure C3A is

suppressed by CaCO3 due to the formation of the low form of calcium

carboaluminate (C3A.CaCO3.11 H2O) on the surface of the C3A grains.

They concluded that C3A reacts with CaCO3 by a direct mechanism.

Bensted (1980) found that in the absence of gypsum, C3A reacts with

CaCO3 in limestone to form both “hexagonal prism” phase tricarbonate

C3A.3CaCO3.30H2O and the “hexagonal plate” phase monocarbonate

C3A.CaCO3.11 H2O. In Portland cement, ettringiteis formed during early

hydration, with monosulfate becoming significant only after the first 16

hours of hydration, when the concentration of sulfate ions is not

sufficient for the formation of ettringite. Tricarbonate is much less stable

than ettringite at ambient temperatures; thustricarbonate does not form in

cement hydration. Bensted examined the possibility of substituting

limestone for some or all of the gypsum used to control the early

hydration of C3A and concluded that because of differences in their

stereochemistry, sulfate ions enter more readily than carbonate ions into

solid solution. Thus sulfate ions are more effective in controlling setting

than carbonate ions. However, he concluded that in a given system it is

possible to substitute limestone for 25% or even 50% of the gypsum

without deleterious effect. The exact amount of substitution depends on

the cement. Kantro (1978) found that limestone at 500 m2/kg Blaine has

some effect on the setting of cement, but is less effective than gypsum in

controlling flash set. For high-sulfate clinker, however, times of set were


12

not markedly different from those for cements in which the gypsum

content was optimized.

Campiteli and Florindo (1990) examined the effects of limestone content

and cement fineness on the optimum sulfate content of cement according

to ASTM C 563. They found that optimum SO3 increases with increasing

fineness and decreases with increasing limestone content, but neither

relationship is linear. They explain the results by noting that when part of

the clinker is replaced by limestone, the coarser fractions of the

interground cement will consist primarily of clinker, while limestone will

be concentrated in the finer fractions. Thus when comparing cements

with the same specific surface, replacing clinker with limestone implies

coarser – and thus slower reacting – clinker particles.

Sprung and Siebel (1991) consider that the calcite from limestone

participates only to a small extent, if at all, in the hydration reactions,

primarily on the surface of the limestone particles. Thus in practice the

limestone should be considered an inert material.

It is important to note that even a chemically inert material can have

significant physical effects. The effects of improved particle packing on

water demand and of increased surface area on bleeding have been noted

in section (2.4.1) An important physical effect on hydration is the

provision of nucleation sites for the hydration products. Sellevold et al.

(1982) found that the presence of nucleation sites accelerates the

hydration of the cement. Livesey (1991b) also found that the use of 5%

limestone resulted in an acceleration of the early hydraulic activity of the

clinker. In their study of cements containing 0% to 35% limestone,

Tezuka et al. (1992) found that the hydration of the cement during the

first seven days was accelerated by the presence of blended limestone

except at the 35% level. Their control cement had a C3A content of 6%

and a specific surface area of 339 m2/kg. Limestone finenesses were 350,

450, and 550m2/kg. Soroka and Setter (1977) also found evidence of

acceleration effect due to the presence of limestone. Ramachandran and

Zhang (1988) obtained a similar result even for 5% CaCO3. Soroka and


13

Stern (1976) also found evidence of an acceleration effect due to the

increased number of nucleation sites.

Barker and Cory (1991) observed that the formation of calcium

hydroxide and ettringite is enhanced at early ages in cements containing

5 and 25% limestone. They studied specimens hydrated for 1, 2, 4, 7, 28,

90, and 180 days using X-ray diffraction and TGA. They normalized

their measured values to the clinker content in order to eliminate the

dilution effect. They found that for 5% limestone, the amount of calcium

hydroxide at 1 day was greater than for the parent cement, but after 2

days the calcium hydroxide contents were similar for the two cements.

For the 25% limestone cements the amount of calcium hydroxide was

generally similar, most likely because the finenesses of the cements were

similar.

In contrast to the results of Sprung and Siebel (1991) who considered

limestone to be inert, Stark, Freyburg, and Löhmer (1999) found that

monocarboaluminate forms when C3A or C4AF reacts in the presence of

6% sulfate and 3% or 6% limestone. The difference may be attributed to

the fineness of the limestones used; Stark, Freyburg, and Löhmer used a

range of limestone finenesses from 680 to 1370 m2/kg (Blaine) and

noticed an increase in reactivity with finer limestones. Accelerated

hydration of C3S, C3A, and C4AF was also noted. Péra, Husson, and

Guilhot (1999) also observed an acceleration of C3S hydration using

between 10% and 50% limestone at 680 m2/kg.

2.3.2 Analysis of composition

The Bogue calculation is a mean of estimating the amount of the

dominant minerals available in a cement, based on its oxide composition.

It assumes that equilibrium is achieved in the cement kiln and the

compounds (C3S, C2S, C3A, and C4AF) have an ideal stoichiometry –

assumptions that are often inaccurate (e.g. Taylor 1997). The effects of

free lime, magnesia, and alkalis can also significantly affect the

compositions.However, knowing the potential phase compositions is


14

important to assessing the properties of the cement. ASTM C 150

specifies an upper limit on the amount of C3A for all but Type I and IA

cements. For Type IV cements, there is also an upper limit on the amount

of C3S and a lower limit on the amount of C2S. The Bogue equations

used in ASTM C 150 are:

C3S = 4.071 CaO - 7.600 SiO2 - 6.718 Al2O3 - 1.430 Fe2O3 -2.852 SO3

C2S = 2.867 SiO2 - 0.7544 C3S

C3A = 2.650 Al2O3 - 1.692 Fe2O3

C4AF = 3.043 Fe2O3

The 2.852 SO3 term in the C3S equation is used to correct the calculation

for the amount of gypsum and thus does not apply to calculations for

clinker. These equations apply for A/F ≥ 0.64. The rare case for which

A/F < 0.64 will be ignored here; Gebhardt (1995) reports only 3 cases out

of 387 cements meeting this criterion.

The effect that limestone will have on the calculated Bogue compositions

depends on the oxide composition of the limestone itself. Table (2-3)

shows analyses for several limestones and the apparent Bogue compound

calculation for each. Note that the apparent Bogue compounds for

limestone are fictional as the material is not pyroprocessed. It can be seen

that the effect of incorporating limestone is to increase the apparent C3S

content and decrease the C2S content. There is a very slight increase in

apparent C3A content. Thus, the effect of using 5% limestone on a typical

Portland cement is to raise the apparent (Bogue-calculated) amounts of

C3S and C3A, while reducing the apparent C2S content. As ASTM C 150

specifies maximum for C3S and C3Aand minimum for C2S, the use of

limestone, in effect, “forces” the cement to be further within the limits if

no correction is made to the Bogue calculation for the cement with

limestone. Table (2-4) gives examples of this effect for 2.5% or 5%

limestone on average Type II and Type IV cements, those with the

strictest limits on composition. Note that the corrected (including only

pyroprocessed material) amount of C3S accounts for the limestone

content and thus is lower than the apparent value. Likewise, the corrected


15

C2S content is higher than the apparent value. The effect on the C3A

contents is negligible. If the apparent values, as estimated by the Bogue

equations (without correction for limestone content), are within the

values specified by ASTM C 150, then the corrected values will also be

within limits. Any error introduced by not correcting for the presence of

limestone will be on the conservative side. Other relevant ASTM C 150

limits are the maximum loss on ignition (L.O.I) of 3.0% (2.5% for Type

IV) and the maximum insoluble residue (I.R) of 0.75%. Pure calcite,

CaCO3, the major component of limestone, has an L.O.I value of 44.0%

(and an IR of 0.0%). Table (2-3) shows that the L.O.I of some limestones

is as low as 35%.A 5% limestone content would increase the L.O.I by

between about 1.7% and 2.2%. Since the average cement of any type has

an L.O.I of more than 1.0% , see Table (2-5), the 3.0% limit could be

exceeded if 5% is used. For many cements, this effectively places an

upper limit on the maximum amount of limestone that can be used in

ASTM C 150 cements. Natural limestone is not pure calcite and can

contain appreciable quantities of clays and other minerals, with insoluble

residues of up to 30%. If a typical cement has an insoluble residue of

0.25% (Gebhardt 1995), then at a 5% limestone content, the insoluble

residue of the limestone would be limited

to about 10% in order not to exceed the insoluble residue limit in ASTM

C 150. Thus the insoluble residue limit in ASTM C 150 also limits the

maximum limestone usage.


16

Table (2-3): Typical Limestone Compositions and Apparent Bogue

Compositions

Limestone A B C D E

SiO2 4.00 13.60 2.00 12.05 2.96

AL2O3 0.77 2.50 0.80 3.19 0.79

Fe2O3 0.30 0.90 0.20 1.22 0.30

CaO 51.4 43.4 52.9 43.5 52.3

MgO 1.30 3.20 0.90 1.68 1.30

SO3 0.10 0.10 0.20 0.56 0.03

LOI 42.0 35.6 42.5 36.21 42.18

Na2O 0.01 0.12 0.04

K2O 0.02 0.60 0.20 0.72 0.23

Total 99.9 99.6 99.7 99.25 100.13

Apparent

values

C3S 173.0 55.0 155.9 60.7 184.6

C2S -119.0 -2.5 -111.9 -11.3 -130.8

C3A 1.5 5.1 1.5 6.4 1.6

C4AF 0.9 2.7 0.6 3.7 0.9

Source Moore

1996

Bayles

1985

Bayles

1985

Klieger

1985

Klieger

1985


17

Table (2-4): Effect of Limestone1 on Average2 Type II and Type IV

Cements’ Bogue Calculation3

Cement

type

Bogue

phase

Average

cement :

apparent

With 2.5%

uncorrected4

With

2.5%

corrected5

With 5%

uncorrected4

With

5%

corrected5

Typ

e II

,

Lim

esto

ne “

R”

C3S 53 53 52 54 50

C2S 21 20 20 19 20

C3A 6 6 6 6 6

C4AF 11 10 11 10 10

Typ

e IV

,

Lim

esto

ne “

R”

C3S 41 42 40 43 39

C2S 33 31 32 30 31

C3A 4 4 4 4 4

C4AF 15 15 15 15 14

Typ

e II

,

Lim

esto

ne “

Q”

C3S 53 57 52 60 50

C2S 21 16 20 13 20

C3A 6 6 6 6 6

C4AF 11 10 11 10 10

Typ

e IV

,

Lim

esto

ne “

Q”

C3S 41 45 40 49 39

C2S 33 28 32 24 31

C3A 4 4 4 4 4

C4AF 15 15 15 15 14

1 Limestone data taken from Klieger1985.,2 Gebhardt 1995.

3 Per ASTM C 150.,4 Based on weighted average of oxide compositions.

5 Apparent Bogue composition corrected for limestone content.


18

Table (2-5): Average Characteristics of Portland Cements (Gebhardt

1995)

Type of cement Loss on ignition Insoluble residue

Type I 1.39 0.26

Type II 1.15 0.27

Type III 1.31 0.25

Type IV 1.18 0.21

Type V 1.02 0.25

N. Voglisa, et al.(2005) studied the effect of limestone, fly ash, pozzolana

in hydration of Portland-composite, the principal hydration products in

composite cements are essentially similar to those found in pure Portland

cement. Of course, in composite cement pastes, Ca(OH)2 content is

lowered, both by them, dilution of clinker and the pozzolanic reaction.

Figure (2-3) presents, indicatively, the X-ray patterns of PFC pastes after

1, 2 and 28 days of hydration. Despite the gradual decrease of the

anhydrous compounds of clinker, there is no increase of Ca(OH)2 content

since it is consumed in the pozzolanic reaction. In the pastes containing

fly ash, there are, also, indications of C2AH8 formation, probably due to

the release of Al2O3 from the fly ash. In limestone cement pastes,

carbonate ions incorporated in calcium aluminate hydrates and

carboaluminatesare formed. Figure (2-4) presents the XRD patterns of

limestone cement pastes at different ages. As it is observed, a detectable

amount of 3CaO.Al2O3.CaCO3.11H2O has already been formed after 24

h of hydration and its amount continues to increase up to 28 days. The

peak next to carboaluminates is associated with Ca–Al– Si hydrates,

probably in the form of gismondine. Figure (2-5) presents the XRD

patterns of the samples after 7 days of hydration. Ettringite (AFt) and

Ca–Al–Si hydrate have been formed in all samples. However,

differentiations are observed as far as the formation of calcium

monosulfate hydrate (AFm) is concerned. It seems that fly ash


19

accelerates the transformation AFt to AFm, while natural pozzolana and

limestone act as retarders.

Table (2-6) presents the content of Ca(OH)2, measured by means of

thermogravimetry, in pastes hydrated for 28 days. The higher content of

calcium hydroxide is found in PC paste while the lower one is found in

PFC paste. The limestone addition does not affect the amount of CH

formed. It must be noticed that it is not possible, based on the CH

measurements, to draw clear conclusions concerning the reactivity of the

cement mixtures, as the clinker fineness also affects the CH content.

Comparing the three composite cements and taking into account that (a)

PFC has the lower fineness, (b) clinker has the lower fineness in PFC and

(c) all the cements have the same 28 day compressive strength, it is

strongly indicated that the addition of fly ash leads to more reactive

cement mixture. Taking into consideration the above results,it is

concluded that the intergrinding of the additives with the clinker causes

important variations of the clinker fineness, especially in the case of fly

ash and limestone.

Consequently, composite cements containing the examined materials

present significant differences as far as the development of the strength,

the water demand and the hydration rate is concerned.

Fig. (2-3): XRD patterns of PEC pastes

(1: ettringite, 2: calcium monosulfate hydrate, 3: Portlandite (C–H), 4: gismondine2 (CaAl2Si2O8.4H2O), 5: quartz, 6: anhydrous compounds of clinker).


20

Fig. (2-4): XRD patterns of PLC pastes

(1: ettringite, 2: monocarboaluminate hydrate, 3: Ca–Al–Si hydrate).

Fig. (2-5): XRD patterns of composite cement pastes at 7 days

1: ettringite, 2: calcium monosulfate hydrate, 3: monocarboaluminatehydrate, 4: Ca–Al–Si hydrate)


21

Table (2-6): Ca(OH)2 content in pastes hydrated for 28 days

Sample PC PLC PPC PFC

Ca(OH)2 (%) 21.37 18.57 19.13 17.22 PC: Portland cement PLC: composite cements containing limestone PPC: composite cements containing natural pozzolana PFC: composite cements containing fly ash

2.3.3 Heat evolution

Hooton (1990) obtained commercial cements from plants producing

ASTM and CSA cements from the same clinker. He determined the 7-

day values for heat of hydration according to ASTM C 186 and found

that there was no consistent effect of limestone on heat of hydration: In

one case the heat of hydration was unchanged, in one case higher, and in

one case lower.

Albeck and Sutej (1991) found that the heat of hydration of the Portland

and Portland limestone cements of the same strength grade were 290 and

280 J/g, respectively, since the finer grinding of the Portland limestone

cement compensated for the reduced clinker content.

Barker and Matthews, reporting results from the Building Research

Establishment study (1993), discuss isothermal conduction calorimetry

and simulated large pour data for cements containing 5% limestone. They

found that in general the use of 5% limestone tends to reduce the peak

rate of heat evolution. However, its effect on the timing of the peak

depends on the method of preparation of the limestone cements. Those

prepared by blending show either no effect or some retardation, while

those prepared by intergrinding (usually also having higher finenesses

than the parent cements) show an acceleration of peak heat evolution.

The cement prepared with a limestone having a high clay content

retarded the peak heat evolution. In general, the total heat evolved is

reduced by the presence of limestone. However, Ramachandran and

Zhang (1988), using a 12.8% C3A cement and reagent grade CaCO3 with

a nitrogen surface area of 6.5 m2/g, found that the CaCO3 increases the


22

total heat evolved. Ramachandran (1988) also found that the total heat

evolved in a C3S paste in the first 24 hours increased with increasing

CaCO3 contents.

Livesey (1991a) determined the heat release characteristics of concretes

made from cements having various limestone contents by isothermal

conduction calorimetry. Increasing limestone content reduced both the

rate and total amount of heat released. Where cements were of a similar

fineness to that of the parent cement without limestone, the introduction

of limestone retarded the maximum heat evolution, but where the

limestone cements had greater fineness they accelerated heat evolution.

He found a good correlation between concrete strength grade (28 days)

and the temperature rise, regardless of cement type.

Vuk et al. (2001) found heat of hydration to be similar in cements with

and without 5% limestone after 3 days, but for higher fineness cements

(on the order of 400 to 440 m2/kg compared to cements on the order of

300 to 370 m2/kg), a slight drop in heat of hydration of cements with 5%

limestone relative to the control was noted.

2.3.4 Microstructure

In a study of the effects of silica fume on the hydration and pore structure

of cement paste, Sellevold et al. (1982) used CaCO3 having the main

body of the particles smaller than 0.1 μm as one of the controls. They

compared mercury intrusion data for mature pastes with and without 12%

CaCO3. The specimens containing CaCO3 had finer pore structures and

somewhat reduced total pore volume. They attribute this observation to

the nucleation effect: The introduction of a large number of nucleation

sites could result in a more homogeneous distribution of calcium silicate

hydrate and thus a less open pore structure. The effect to be in the

capillary pore structure rather than in the gel pores.

Barker and Cory (1991) observed that use of 25% limestone influences

both the size and distribution of calcium hydroxide deposits in cement

paste. They found that in ordinary Portland cement paste small regions of


23

calcium hydroxide are evenly distributed throughout the paste, while in

the limestone-filled pastes larger regions of calcium hydroxide were

unevenly distributed throughout the paste. Use of 5% limestone had little

effect on the size or distribution of calcium hydroxide deposits. They also

found that limestone added in amounts of 5% or 25% enhance the

formation of hydration rims of calcium silicate hydrate surrounding C3S

particles because they increase the rate of hydration of C3S. Increasing

levels of limestone increased the formation of ettringite at early ages. The

amount of ettringite then decreased slowly as hydration proceeded. They

did not observe any monosulfate.

2.3.5 Setting time

Hooton (1990) obtained commercial cements from plants producing

ASTM and CSA cements from the same clinker and analyzed the CaCO3

content by TGA. His data for ASTM C 191 setting times are shown in

Table (2-7). There is no clear trend for the effect of limestone on setting

times.

Hawkins (1986) conducted two test series. In the first, clinker and

gypsum were ground in a laboratory ball mill with 0%, 3%, 5.5%, and

8% limestone to a more or less constant Blaine fineness. The use of

limestone appears to have little effect on the setting time. In the second

series, the procedure was repeated with 0%, 2%, 5%, and 8% limestone,

except that the <325 mesh value was kept more or less constant. This

series indicates a reduction in setting time with the use of limestone. In

all tests a Type II low-alkali clinker with a C3A content of 5.1% and a

limestone having 85% CaCO3were used. The SO3 content was

maintained at 2.5%. His data are given in tables (2-8) and (2-9) below.

Adecrease in Vicat setting time was noted by Vuk et al. (2001) with use

of 5% limestone in cements made from two different clinkers: Initial

setting was reduced by 50 minutes with a clinker C3S content of 35% and

by 25 minutes with a clinker C3S content of 46%. The authors note that


24

the effects of clinker composition were less significant when the cement

fineness was higher.

Bobrowski et al. (1977) indicate that false set is reduced considerably

when limestone is used as a partial substitution for gypsum, and that the

setting time was not markedly affected. Samples with and without

limestone were heated to 280°C for 16 hours to force the base system to

false set. The sample with limestone reacted much better, as indicated in

table (2-10). The system with limestone had less gypsum available to

dehydrate upon heating (as might occur in finish grinding); therefore the

tendency to false set might be expected to be less. However, appropriate

control of C3A reaction was observed in this study.

S. Tsivilis et al. (1999) concluded that the setting time and soundness of

Portland limestone cements are satisfactory and similar to Portland

cements.

Table (2-7): Vicat Setting Times for ASTM and CSA Cements

(Hooton )

Cement CaCO3, %

(TGA)

Initial set,

minutes

Final set,

minutes

1 (10.3% C3A) 0.3 175 355

1c 4.1 167 323

2 (9.1% C3A) 0.8 134 283

2c 4.7 119 224

3 (8.3% C3A) 0.3 153 294

3c 2.6 170 340


25

Table (2-8): Vicat Setting Times for Interground Cements at Constant

Blaine (Hawkins 1986)

% Limestone by mass of

total cement 0.0 3.0 5.5 8.0

< 325 mesh, % by mass 90.0 85.5 81.0 82.4

Blaine, m2/kg 371 351 346 364

Initial setting time 2:40 2:50 2:50 2:45

Final setting time 5:00 5:00 4:55 4:50

Table (2-9): Vicat Setting Times for Interground Cements at Constant

<325Mesh (Hawkins 1986)

% Limestone by mass of total

cement 0.0 3.0 5.5 8.0

< 325 mesh, % by mass 94.7 91.9 91.2 91.6

Blaine, m2/kg 390 387 433 470

Initial setting time 3:20 2:25 2:30 2:20

Final setting time 5:10 4:05 4:00 3:50

Table (2-10): Use of Limestone Substitution to Reduce False Set

(Gilmore) (Bobrowski et al. 1977)

Cement property Base sample

4.5% gypsum

Test sample

1.75% gypsum +

2.25% limestone

Blaine surface area (m2/kg)

SO3 (%)

Setting time: (min.)

Full needle

Initial set

Final set

479

1.96

0

4

217

481

0.95

58

147

320


26

2.4 Fresh mortar and concrete

2.4.1Particle Size Distribution

2.4.1.1 Comminution

According to Schiller and Ellerbrock (1992), the characteristics of

cements comprising several components are influenced by both the

particle size distributions and the chemical-mineralogical compositions

of the component materials. Since interground limestone often

participates to a lesser extent or not at all in the hydration reactions,

cements of the same fineness that contain significant quantities of

interground additives will have lower strengths than corresponding

cements without these additives, due partly to dilution and partly to a

concentration of the clinker in the coarser particle fractions. The loss in

strength may be compensated for either by a strength increase resulting

from the narrower particle size distribution of the clinker fraction (the

result of intergrinding with a more easily ground material such as

limestone), or by overall finer grinding of the cement. Schmidt (1992a)

reports that for levels of limestone between 5% and 10%, cement and

concrete strengths are not normally reduced; thus finer grinding may not

be necessary. However, Hawkins' (1986) data illustrate that in some

cases finer grinding may be needed at low limestone contents see

Cement property Base sample

4.5% gypsum

Test sample

1.75% gypsum +

2.25% limestone

C 359: False set, mortar method

Initial penetration

5 Minutes

8 Minutes

11 Minutes

Remix

50+

17

1

0

26

50+

50+

47

15

50+


27

Section (2.5.1.1). For cement near the AASHTO M 85 fineness limit

(400 m2/kg), finer grinding may not be an option.

Sprung and Siebel (1991) point out that in Portland limestone cements

(CEM II), the saving of fuel energy that comes about by substituting

limestone for some of the clinker is partially offset by the additional

electrical energy required for the finer grinding to produce a cement with

the same strength as the same cement without limestone. However, CEM

II cements contain up to 30% limestone. The data of Schiller and

Ellerbrock (1992) indicate that at the 5% level, the amount of additional

finish grinding energy is less than 2 kWh/t. This increase

would be more than offset by other savings in energy (Nisbet 1996),

estimated to be on the order of 75 kWh/t. In their study of the

comminution of cements comprising several constituents of varying

grindability, Schiller and Ellerbrock (1992) found that the particle size

distributions of any one constituent is greatly influenced by the

grindabilities of the others. Material which is harder to grind becomes

concentrated in the coarser fractions, while material which is easier to

grind becomes concentrated in the finer fractions. Figure (2-6) shows the

particle size distributions of a Portland limestone cement and its two

individual constituents after intergrinding in an industrial ball mill.

The particle size distribution of the clinker, which is harder to grind, is

narrower, with a slope (n) equal to 1.1 on a Rosin-Rammler-Sperling-

Bennett (RRSB) diagram.That of the more easily ground limestone, on

the other hand, is wider, with a slope of 0.7. In addition, the position

parameter (x’) of the limestone fraction is 5μm, while that of the clinker

fraction is 25 μm. The position parameter is defined as the equivalent

spherical diameter which 38.6% by mass of the material is coarser than, a

measure of the fineness of the material. For the purposes of quality

control of cement production, a similar relation would be determined for

the specific materials in the specific proportions to be used, ground in

particular mill where they were to be produced, since the relative


28

grindabilities and proportions of the materials and the specific grinding

process all influence the outcome.

Fig. (2-6): Cumulative mass distributions of a Portland limestone

cement with a limestone content of 12% by mass, as well as

of the two individual constituent materials after

intergrinding in an industrial ball mill (after Schiller and

Ellerbrock, 1992).

According to Schiller and Ellerbrock (1992), to produce cements having

a 28-day strength of 50 MPa, the position parameter would be reduced

from 30 μm for a plain Portland cement to 26 μm for a 10% limestone

cement and to 14 μm for a 20% limestone cement.

Moir (1995) points out that in modern milling systems equipped with

high efficiency separators, the particle size distributions are steeper than

with conventional separators. This narrow particle size grading may

result in increased bleeding and delays in initial setting time. The

inclusion of up to 5% limestone broadens the particle size grading,

Cu

mu

lati

ve m

ass

dis

trib

uti

ons

Q(ᵡ

),

wei

ght%

Particle size ᵡµm


29

offsetting these disadvantages. He cites the example of a cement plant

which converted from an open circuit mill to a closed circuit mill with

high efficiency separator in 1992. In this caseinterground limestone in the

amount of 4.1% was required to control the strength while optimizing the

rheological and setting behavior. The limestone in the cement is

concentrated in the 5 to 20 μm size fraction.

Limestone need not be interground with the clinker, although dry

blending produces a somewhat different particle size distribution. In a

1993 Building Research Establishment (BRE) study, the average specific

surface of the cements increased from 300 to 350 m2/kg and the 45 μm

residue from 13.8% to 15.8% when 5% limestone was interground with

the clinker (Jackson 1993). When cements were dry blended with 5%

limestone, the specific surface increased from 395 to 486 m2/kg and the

45 μm residue decreased from 12.0% to 10.8%. The authors caution that

if the limestone is to be incorporated by blending rather than by

intergrinding, it must be ground to an appropriate level of fineness to

achieve a minimum water demand. Sprung and Siebel (1991) found that

separate grinding of the limestone samples they studied in a batch-

operated ball mill generally led to very wide particle size distributions

with RRSB diagram gradients (n) of less than 0.9, and sometimes even

less than 0.8. They observed that the wide particle size distribution with a

high proportion of fines resembles the particle size distributions normally

found in the limestone fraction of interground Portland limestone cement.

Ménétrier-Sorrentino (1988), however, implied that separate grinding of

the constituents of Portland limestone cements offers greater opportunity

for optimization of the particle size distribution of the individual

materials. She points out that the concentration of the clinker in the larger

particle fractions may not allow the best use of the material, particularly

for the development of early strength.

S. Tsivilis et al. (1999) concluded that the appropriate choice of the

clinker quality, limestone quality and % content and cement fineness can

lead to a cement production of desired properties.


30

S. Tsivilis et al. (2002) concluded that the particle size distribution of the

Portland limestone cements, as well as the fineness of clinker and

limestone, is strongly connected with the limestone content and the

fineness of the cement.

2.4.1.2 Workability of paste, mortar, and concrete

Sprung and Siebel (1991) point out that particle size distribution has a

considerable influence on the water demand of a cement. Narrow particle

size distributions with RRSB gradients (n) greater than 1 generally result

in high water demand, while wide particle size distributions lead to

reduced water demand (Detwiler 1995). The easily ground limestone

usually has a wide particle size distribution which allows the limestone

particles to fill the gaps between the clinker particles, reducing the water

demand and densifying the structure of the hardened cement paste. These

physical effects apparently more than compensate for any surface effects

that would tend to increase the water demand associated with the finer

material. According to Sprung and Siebel (1991), this densifying effect

can lead to increased strengths when the limestone content is less than

10%. They also found that water demand was related to the clay content

of the limestone: If the methylene blue value (CEN 1998–discussed in

Section 2.6.1 of this report) of a limestone was high, the water demand

would be higher than would be expected from the particle size

distribution alone.

The relationship among particle size distribution, strength, and water

demand is well established. Schiller and Ellerbrock (1992) observed that

Portland cements having the same specific surface harden faster, but have

higher water demands the narrower their particle size distributions. They

studied Portland limestone cements made by both intergrinding and

blending the component materials. In one experiment they mixed ground

clinker with a position parameter (x’) equal to 20 μm and slope (n) equal

to 0.88 with two different limestone meals having the same Blaine

fineness of 580 m2/kg, but different particle size distributions. The


31

Portland limestone cements having limestone contents of 10%, 20%, and

30% all had Blaine finenesses of about 390 m2/kg. In quantities of up to

10%, the use of limestones, with either narrow or wide particle size

distributions, decreased the water demand of the cement. Since both

limestones had different particle size ranges than the clinker, mixing

either of them with the clinker broadened the total particle size

distribution. In greater quantities, the limestone with the wider particle

size distribution continued to reduce the water demand of the cement,

while that with the narrower particle size distribution increased the water

demand. They also found that even when Portland limestone cement had

to be ground finer in order to achieve the same strength as Portland

cement made from the same clinker, the water demand was lower

because of the improved particle size distribution.

Tezuka et al. (1992) found that the workability of mortars of different

cement contents improved with the use of limestone even at 5% levels.

This translated to a reduction in water: cement ratio from 0.49 to 0.48 to

achieve a constant consistency. Ground quartz added in the same

proportions increased the water demand. They attribute the beneficial

effect of limestone to a more favorable particle size distribution which

better complements that of the clinker. Similarly, Brookbanks, reporting

results from the Building Research Establishment study (1993), stated

that replacing 5% of the cement with limestone dust or dried silt from a

gravel aggregate increased the required water: cement ratio of concrete

by an average of 0.01 and 0.02, respectively, over that required when a

factory-made limestone-filled cement was used. This illustrates the

advantage of optimizing the particle size grading of the limestone.

In a study of cements containing up to 15% of a limestone having a

relatively high CaCO3 content, Neto and Campiteli (1990) found that in

two-point measurements of the consistency, the yield point values were

decreased and theplastic viscosity slightly increased by the presence of

limestone, especially for the finer cements. In practical terms, this means


32

that the mortar is somewhat stiffer and more inclined to stay in place, but

less viscous and more easily consolidated by vibration.

Sprung and Siebel (1991) found that for concretes made according to the

same mix design, those made with Portland limestone cement were less

stiff than those made from Portland cements. In concrete, once surface

forces are neutralized by a water-reducing admixture or superplasticizer,

the water requirement is not a function of surface that must be wetted,

but of interparticle space that must be filled. Schmidt (1992a) explains

the beneficial effect of limestone on concrete rheology in terms of

improvements in the particle size distribution: The fine particles displace

some of the water from the voids between the coarser particles, making it

available as an additional “internallubricant.” Thus the concrete is less

stiff and water retention is improved. The effect is further reinforced if

the hydration reactions are retarded so that less water is chemically

combined due to the inertness of the limestone fraction. The latter effect

will depend on the fineness and proportion of limestone in the concrete.

Since less water is needed to make a workable mix, the water content can

be reduced so that the strength is increased. Schmidt et al. (1993) cite the

example of concretes having the same consistency. Those made with

Portland limestone cements (13% to 17% limestone) required about 10

l/m3 less water, so that the water: cement ratio was reduced from 0.60 to

0.57 and the strength increased by as much as 8 MPa. Moir (1995) found

that water demand in concretes made from Portland cements with and

without 5% limestone was not affected by the presence of limestone in

normal and rich mixes, but was reduced in lean mixes. Brookbanks,

reporting work done in the Building Research Establishment study

(1993), found similar results. His data are shown in table (2-11).

Finely ground limestone has long been used in masonry cements to

improve the retention of water in the mortar. Schmidt (1992a) studied the

bleeding in mortars made with Portland cement and Portland limestone

cement. After two hours standing time, the amount of bleed water from


33

the Portland limestone cement mortar was less than half that from the

Portland cement mortar.

Table (2-11): Water: cement Ratio to Achieve 60-mm Slump

(Brookbanks 1993)

Cement content

Kg/m3

0%

Limestone

5%

Limestone

225 0.92 0.89

300 0.60 0.60

350 0.52 0.52

Albeck and Sutej (1991) report the development of a Portland limestone

cement for strength class 35. Because of the high quality of the clinker

used, the Portland cement PZ 35 F had to be ground coarsely in order not

to exceed the strength limit. By intergrinding 18% limestone (CaCO3

content of 90.8%) with the clinker they were ableto produce a Portland

limestone cement (PKZ 35 F) meeting the strength requirements. They

measured the bleeding for a series of concretes and found that those

made with PKZ 35 F always exhibited less bleeding and stopped

bleeding sooner than those made with PZ 35 F. The coarser the sand

used, the more significant the difference between the two cements. Their

data are shown in table (2-12).

In mass concrete, Kanazawa et al. (1992) found that finely ground

limestone improved the workability, reduced bleeding, and aided in the

development of early strength. This concretemix also contained finely

ground blast furnace slag. Because of the need to minimize heat

generation, setting times were delayed, with the result that any tendency

to bleed is exacerbated. The fine aggregate used was sea sand. In

preparing this type of aggregate, the washing that is necessary to remove

the salt also removes the finest sand fraction. The finely ground

limestone replaced these fines, effectively controlling bleeding.


34

Table (2-12): Bleeding of Fresh Concrete, kg bleed water/m3 concrete

(Albeck and Sutej, 1991).

Sand cement 0.5 h 1.0 h 1.5 h 2.0 h 2.5 h 3 h

Oberrhein PZ 35 F 6.2 9.7 11.3 12.3 13.2 13.8

PKZ 35 F 3.0 5.9 8.3 9.8 11.0 11.8

Pleinfeld PZ 35 F 5.8 11.5 13.7 14.4 15.1 15.8

PKZ 35 F 2.9 5.5 7.4 8.3 8.8 --

München B PZ 35 F 4.8 7.4 9.0 9.9 8.6 10.1

PKZ 35 F 4.0 5.5 6.4 6.8 6.9 --

Sand cement 0.5 h 1.0 h 1.5 h 2.0 h 2.5 h 3 h

Donau PZ 35 F 6.0 8.3 9.1 9.9 10.2 11.0

PKZ 35 F 2.6 4.3 5.3 5.5 -- --

München R PZ 35 F 3.2 5.3 6.6 7.7 8.2 8.4

PKZ 35 F 3.4 4.2 5.4 6.1 6.4 6.6

Standard PZ 35 F 3.9 6.4 7.5 8.2 8.4 8.9

PKZ 35 F 2.6 4.2 5.3 5.8 6.4 7.0

Allgaü PZ 35 F 2.3 4.5 6.5 8.0 9.2 10.0

PKZ 35 F 2.1 3.7 5.2 6.2 6.9 --

"__" indicates data not reported.

In studies of 5% limestone Portland cements, Moir (1995) found that

bleeding in concrete is related only to the cement surface area

independent of the presence of limestone. That is, the effect of limestone

at low concentrations is purely a physical one related to particle packing

and surface forces. Brookbanks, reporting results from the Building

Research Establishment study (1993), showed improvements in the

bleeding characteristics of concretes made with cements containing 5%

limestone over those made with cements of the same strength class


35

without limestone. His data are summarized in table 2-13. It should be

noted that these two researchers are not reporting conflicting results.

Moir is keeping surface area constant, while Brookbanks is not.

Vuk et al. (2001) also noted a slight reduction (0.5%) in water demand

with the use of 5% limestone and noted that the more important

parameter influencing water demand was cement fineness.

Table (2-13): Average Bleeding Characteristics for Concretes With and

Without 5% Limestone in Cement (Brookbanks 1993)

2.5 Hardened Mortar and Concrete

2.5.1 Mechanical properties

2.5.1.1 Strength and Strength Development

Hooton (1990) tested three pairs of cements made from the same clinker

with and without interground limestone conforming to the CSA limits.

His data for the compressive strengths of mortar cubes are given in table

(2-14).

Albeck and Sutej (1991) showed that the strength development of their

commercial Portland cement (PZ 35 F) and Portland limestone cement

(PKZ 35 F) made from the same clinker to the same strength class

(Blaine fineness of about 400 m2/kg) over the period January 1989 to

May 1990 were quite similar, with the variability similar or somewhat

Bleeding

Characteristics

0%

Limestone

5%

Limestone

Bleeding rate,

cm/min. x 104 43 22

Bleeding capacity,

ml/cm2 0.27 0.18

Total bleed water,

% by mass 10.0 6.5


36

lower for the Portland limestone cement. Their data are shown in table

(2-15).

Table (2-14): ASTM C 109 Mortar Cube Strengths, MPa (Hooton

1990)

Cement 1 1c 2 2c 3 3c

% C3A 10.4 10.0 9.1 9.8 8.3 7.3

% CaCO3(by

TGA) 0.3 4.1 0.8 4.7 0.3 2.6

Age

2 days 27.0 21.4 22.7 21.2 18.5 21.0

3 days 29.3 24.1 26.4 24.2 22.4 24.7

7 days 33.4 28.7 31.5 29.3 27.8 29.0

28 days 40.8 36.4 41.3 36.4 35.0 35.3

16 months 51.1 49.6 45.6 42.1 43.6 45.4

Table (2-15): Average Strengths and Standard Deviations for Cements

Produced at Mergelstetten Plant January 1989 – May

1990, MPa (Albeck and Sutej, 1991)

Type of cement Mean Standard deviation

PZ 35 F 2-day strength 24.1 1.59

28-day strength 52.0 1.87

PKZ 35 F2-day strength 24.4 1.59

28-day strength 50.2 1.61

Hawkins (1986) conducted two test series. In the first, clinker and

gypsum were ground in a laboratory ball mill with 0%, 3%, 5.5%, and

8% limestone to a more or less constant Blaine fineness. In the second

series, the procedure was repeated with 0%, 2%, 5%, and 8% limestone,


37

except that in this series the <325 mesh value was kept more or less

constant. In all tests a Type II low-alkali clinker with a C3Acontent of

5.1% and a limestone having 85% CaCO3were used. The SO3 content

was maintained at 2.5%. His data are given in tables (2-16) and (2-17).

They show that with the fineness increase, limestone cements give

comparable strengths.

Table (2-16): Strengths of Cements at “Constant” Blaine, MPa

(Hawkins 1986)

% Limestone 0.0 3.0 5.5 8.0

< 325 mesh,% 90.0 85.5 81.0 82.4

Blaine, m2/kg 371 351 346 364

1 day 6.41 5.10 4.83 4.69

3 days 18.61 16.13 14.62 14.07

7 days 25.92 22.61 19.93 19.79

28 days 35.51 31.65 28.06 27.17

3 months 40.40 38.13 34.75 33.99

6 months 42.82 40.89 39.99 38.82

12 months 44.33 43.23 41.71 41.37

Bédard and Bergeron (1990) studied the effect of carbonate use on the

strength of heat-cured concrete. Two CSA Type 30 cements and

companion cements with intergroundlimestones from two different

sources were used to make the concretes. The dosages of limestone were

chosen to suit the chemistry of the cements. The first cement had a C3A

content of 10.4% and was tested with and without 4.1% Limestone A.

The second had a C3A content of 11.6% and was tested with and without

2.3% Limestone B. The particle size distributions of control and test

cements were similar in both cases. Figure (2-7)shows the strength


38

developments for the concretes in the first 24 hours. The strengths are

quite similar. Their data for normal curing are shown in table( 2-18). In

all cases, except the cement with and without Limestone B at day, the

differences between the concrete strengths are negligible.

Fig. (2-7): Effect of heat curing on the compressive strength of

concretes made with and without limestone. “Test A”

contains 4.1% limestone and “Test B” contains 2.3%

limestone (after Bédard and Bergeron, 1990).

Com

pre

ssiv

e st

ren

gth

, MP

a

Time, hours


39

Table (2-17): Strengths of Cements for “Constant” < 325 Mesh, MPa

(Hawkins 1986)

% Limestone 0.0 3.0 5.5 8.0

< 325 mesh,% 94.7 91.9 91.2 91.6

Blaine, m2/kg 390 387 433 470

3 days 20.20 20.82 21.17 21.93

7 days 27.65 27.72 28.68 28.27

28 days 39.92 39.09 39.02 38.96

3 months 45.22 46.06 45.37 45.23

6 months 43.57 45.64 45.37 44.33

12 months 44.75 46.06 45.99 44.88

Table (2-18): Compressive Strengths for Concretes Made With

Cements With and Without Limestone, MPa (Bédard

and Bergeron, 1990)

Test A Test B

Control

A (4.1% limestone)

Control

B (2.3% limestone)

1 day 34.0 34.4 38.4 33.4

7 days 49.3 48.1 52.1 51.7

28 days 56.5 56.0 59.2 57.2

56 days 59.1 62.0 61.4 60.4

Sprung and Siebel (1991) found that the use of inert material as a very

fine filler can lead to an increase in strength due to improved packing of

the particles (i.e., filling of voids between the cement grains). This effect

is seen at early ages, but unlike the case with fly ash or other


40

pozzolanicmaterials, does not produce additional increases in strength

with continued curing. When limestone is included in large quantities

(15% to 25%) it acts as a diluent, so that strengths are lower than for

comparable Portland cements. To an extent, the loss of strength due to

dilution can be offset by finer grinding.

Schmidt (1992a) observed that cement and concrete strengths normally

are not reduced by using 5% to 10% limestone. The dilution effect is

seen at higher dosages unless the cement is ground finer to compensate.

Reductions in the water: cement ratio are often possible because of the

improved particle packing; these will further compensate for the dilution

effect.

Livesey (1991b) reports an investigation of concretes of constant

workability made from cements containing up to 25% limestone. He

found that the use of 5% limestone had little effect on performance,

although at higher levels the properties of the limestone can be

significant. Cement containing 5% limestone showed a somewhat

accelerated strength gain at early ages, particularly when the cement was

more finely ground. The same author in the Building Research

Establishment study (1993) reports that the presence of 5% limestone has

no significant effect on strength, as some strengths are slightly higher and

some slightly lower.

N. Voglis, et al.(2005) studied the effect of limestone, fly ash, pozzolana

in strength gaining and concluded that The cement containing limestone

exhibits higher early strength. The opposite effect is caused by the

addition of fly ash. At 90 days and up to 540 days, cements with natural

pozzolana or fly ash exhibit significantly higher compressive strength

than the Portland cement and the Portland-limestone cement and the

Figure (2-8) show this results.


41

Fig. (2-8): Strength development of cements. PC: Portland cement PLC: composite cements containing limestone PPC: composite cements containing natural pozzolana PFC: composite cements containing fly ash

The chemical composition of the used materials is shown in table (2-

19),while the Bogue potential composition and the moduli of the clinker

are given in table (2-20).The cements have been produced by

intergrinding clinker (85%), the 2nd main constituent (15%) and gypsum

(5% of clinker by mass) in a pro-pilot plant ball mill. The grinding

process was designed in order to produce cements having the same 28d

compressive strength. It is decided to examine cements of the same 28d

compressive strength instead of the same fineness, as this case is closer to

the industrial practice. The main characteristics of the produced cements

are given in table( 2-21).

Age, days

Com

pre

ssiv

e s

tren

gth

, MP

a


42

Table (2-19): Chemical composition of materials (%)

Oxide Clinker Limestone Natural

Pozzolana Fly ash

SiO2 21.99 0.54 59.18 49.33

Al2O3 5.28 0.35 16.12 20.72

Fe2O3 3.79 0.12 6.14 7.98

CaO 65.65 51.95 4.92 10.26

MgO 1.77 1.16 1.96 2.19

Na2Oeq 0.56 0.02 1.41 1.28

LOI 0.00 42.10 4.78 2.02

Table (2-20): Mineralogical composition (%) and moduli of clinker

Bogue potential composition (%) Moduli

C3S C2S C3A C4AF LSF AR SR HM

59.25 18.37 7.57 11.54 93.42 2.42 1.39 2.11

Table (2-21):

Characteristic properties of the cements

Cement

Grinding time

(min)

Specific

surface

(Blaine)

(m2/kg)

28d

Compressive

strength

(MPa)

PC 41 303 40.3

PLC 60 511 40.5

PPC 52 418 41.2

PFC 40 388 41.0


43

Vuk et al. (2001) used a statistically designed experiment to examine the

effects of 5% Thelimestone, cement fineness, and clinker chemistry on

strength. Early strengths of EN 196 mortars increased with use of

limestone; however, later strengths either remained the same or

decreased relative to the control depending on the fineness and the

clinker chemistry. The clinkers were low in C3A content (1.3% or 1.4%)

and relatively low in C3S content (35% or 46%). Figures (2-10) and

(2-11) show a large assortment of data from different sources that

summarize the available data. The ratio of compressive strength for

samples of concrete or mortar made with and without limestone in

Portland cement is plotted as a function of the age of the sample at

testing. Limestone in amounts up to 6% are included. It is interesting to

note that the mean value of this ratio for these data is between 97% and

105% at every age where more than two data points are available. This

result is surprising, as many of the cements were not optimized for

strength, but had arbitrary amounts of limestone added. A test program

such as that used to optimize the gypsum/sulfate content of cements

(ASTM C 563) might be used to determine an optimum value of the

limestone content for a given cement. At the least, these figures confirm

that Portland cements with up to 5% limestone can provide strengths

equivalent to Portland cements without limestone.

Table (2-22) gives the summary statistics for the data. Figures (2-11) and

(2-12) show a subset of the data in Figures (2-9) and (2-10)for samples

made with Type II cements (those with C3A contents below 8%).

Although limited, these data also indicate that equivalent compressive

strengths can be achieved. Figures (2-13) and (2-14) summarize the data

for flexural strength ratio. Although less data are available, the trends are

the same: The average of the ratios is between 0.99 and 1.08 for all ages,

and the overall average is 1.0.


44

Fig. (2-9): The ratio of compressive strengths for mortars made with

Portland cements with up to 6% limestone to that of

companion samples made with Portland cement without

added limestone. The dashed line connects the mean values

at each age. The data represent 374 sets of samples from 11

sources (Bobrowski et al. 1977; Bayles 1985; Crawford

1980; Combe and Beaudoin, 1979; Hawkins 1986; Hooton

1990; Klieger 1985; Livesey 1993; Lane 1985; Matkovic et

al. 1981; and Tsivilis et al. 1999).

Age, days

Com

pre

ssiv

e st

ren

gth

rat

io

(lim

esto

ne/

pla

in)


45

Table (2-22): Summary Statistics for the Compressive Strength Ratio

Data

Age

Mortar data Concrete data

Mean Standard

deviation

Number of

data points Mean

Standard

deviation

Number of

data points

1 day 0.98 0.15 71 0.97 0.12 49

2 days 1.00 0.11 8 - - -

3 days 1.02 0.17 60 1.00 0.11 49

7 days 1.01 0.09 83 1.01 0.10 115

14 days - - 1.03 0.08 10

28 days 0.99 0.06 83 0.97 0.09 127

56-60 days - - - 1.02 0.08 16

90-91 days 1.01 0.07 25 0.98 0.11 74

180 days 1.04 0.09 21 1.15 0.04 2

365 days+ 0.99 0.07 23 0.99 0.09 49

Overall 1.00 0.111 374 1.00 0.18 491


46

Fig. (2-10): The ratio of compressive strengths for concrete made with



The dashed line connects the mean values at each age. The

data represent 491 sets of samples from 10 sources (Bayles

1985; Bedard and Bergeron, 1990; Bobrowski et al. 1977;

Detwiler 1996; Hawkins 1986; Klieger 1985; Livesey

1993; Matkovic et al. 1981; Nehdi et al. 1996; and

Suderman 1985).

Com

pre

ssiv

e st

ren

gth

rat

io

(lim

esto

ne/

pla

in)

Age, days


47

Fig. (2-11): The ratio of compressive strengths for mortars made with




data represent 44 sets of samples from 4 sources with

cement C3A contents less than 8% (Bobrowski et al. 1977,

Hawkins 1986, Livesey 1993, and Tsivilis et al. 1999).

Age, days

Com

pre

ssiv

e st

ren

gth

rat

io

(lim

esto

ne/

pla

in)


48

Fig. (2-12): The ratio of compressive strengths for concretes made with




data represent 72 sets of samples from 5 sources with

cement C3A contents less than 8% (Bobrowski et al. 1977,

Hawkins 1986, Livesey 1993, Nehdi et al. 1996, and

Suderman 1985)

Age, days

Com

pre

ssiv

e st

ren

gth

rat

io

(lim

esto

ne/

pla

in)


49

Fig. (2-13): The ratio of flexural strengths for mortars made with




data represent 59 sets of samples from 3 sources (Combe

and Baudouin, 1979; Livesey 1993; and Matkovic et

al.1981).

Age, days

Fle

xura

l str

engt

h r

atio

(l

imes

ton

e/p

lain

)


50

Fig. (2-14): The ratio of flexural strengths for concrete made with




data represent 15 sets of samples from 1 source (Matkovic

et al. 1981).

2.5.1.2 Volume Stability

Adams and Race (1990) studied the effect of blended limestone on the

drying shrinkage of Type I and Type II cements using ASTM C 596.

They found slight increases in drying shrinkage. Some of their data are

shown in tables (2-23) and (2-24). They also found that optimization of

the sulfate content and/or the use of functional additions could offset the

increased shrinkage.

Hooton (1990) compared pairs of cements ground from the same clinker

with and without limestone in quantities conforming to the CSA limits.

Age, days

Fle

xura

l str

engt

h r

atio

(l

imes

ton

e/p

lain

)


51

His data on autoclave expansions are given in table (2-25). The use of

carbonate had no adverse effect.

Table (2-26) shows the shrinkage data Detwiler (1996) observed for

concretes incorporating either a Type I Portland cement or a Type 10

Portland cement ground from the same clinker with 2.5% interground

limestone. The table shows that the drying shrinkage is not affected by

the use of limestone for the control concretes with or without Class C fly

ash.Shrinkage has been measured on concrete specimens made with

cements from two different plants with and without 20% limestone by

Alunno-Rossetti and Curcio (1997). Their data are presented in table (2-

27). Although, as expected, an increase in shrinkage with increased

cement content is noted, no differences between the cements from the

same plant were observed, in either evolution of shrinkage or final

values.

Table (2-23): Effect of Blended Limestone on Type II Cement, 6.4%

C3A, 400 m2/kg (Adams and Race, 1990)

Control 3%Limestone 5%Limestone

Limestone source - CA CA

Limestone fineness, m2/kg - 966 966

Flow for constant water, % 110 108 103

ASTM C 596 drying shrinkage

4 days, % 0.046 0.049 0.050

11 days, % 0.064 0.067 0.068

18days, % 0.075 0.077 0.079

25 days, % 0.081 0.085 0.085


52

Table (2-24): Effect of Blended Limestone on Type I Cement, 11.4%

C3A, 339 m2/kg (Adams and Race, 1990)

Control 5%

Limestone

Limestone source - TX

Limestone fineness, m2/kg - 1035

Flow for constant water,

% 99 100

ASTM C 596 drying

shrinkage

4 days, % 0.044 0.050

11 days, % 0.063 0.071

18days, % 0.070 0.079

25 days, % 0.072 0.082

Table (2-25):

ASTM C 151 Autoclave Expansions, % (Hooton 1990)

Cement CaCO3 Autoclave

expansion MgO Free CaO

1 0.3 0.038 2.38 0.34

1c 4.1 0.034 2.38 0.18

2 0.8 -0.010 1.88 0.71

2c 4.7 0.029 1.91 1.12

3 0.3 0.093 2.91 0.38

3c 2.6 0.026 2.84 0.34


53

Table (2-26): Drying Shrinkage of Concretes (Detwiler 1996)

Cement

Cement

content

(kg/m3)

Fly

ash:

content

and

type

4

days

7

Days

14

days

28

days

56

Days

12١

Days

Type I 362 none

0.002 0.009 0.015 0.025 0.039 0.044

Type 10 0.003 0.008 0.017 0.025 0.038 0.046

Type I 308

25%

Class C

0.004 0.019 0.019 0.020 0.023 0.046

Type 10 0.003 0.011 0.022 0.026 0.029 0.046

Table (2-27): One-Year Drying Shrinkage (UNI Standard 6555*) of


Limestone (Alunno-Rosseti and Curcio, 1997)

Plant B

Cement content, kg/m3 270 330

Limestone content of

cement, % by mass 0 20 0 20

Shrinkage, μm/m 635 640 680 690

Plant G




Shrinkage, μm/m 540 560 615 595

*Italian national standard. Specimens stored at 50% relative humidity.

N. Voglisa, et al.(2005) studied the effect of limestone, fly ash, pozzolana

in shrinkage, The results of the shrinkage/expansion tests are presented in

table (2-28). The linear shrinkage of the tested cement mortars is


54

satisfactorily low. In addition, the linear expansion is low in all samples,

with PFC indicating the higher value.

Table (2-28): Shrinkage/expansion of the samples

Sample Shrinkage (10_6) Expansion (10_6)

3d 7d 14d 28d 3d 7d 14d 28d

PC 50 80 170 200 10 20 30 40

PLC 20 100 150 210 35 45 45 50

PPC 30 100 130 230 15 20 25 40

PFC 10 80 140 190 35 40 45 75

PC: Portland cement PLC: composite cements containing limestone PPC: composite cements containing natural pozzolana PFC: composite cements containing fly ash

S. Tsivilis et al. (1999) concluded that the linear expansion of limestone

cement mortars is definitely smaller than that of the corresponding pure

cement at any ages.

2.5.2 Durability

2.5.2.1 Permeability

Permeability is the key to the durability of a porous material in all but the

most protected environments. With the exceptions of abrasion and

erosion, deterioration mechanisms involve the ingress of water and/or

other harmful species (oxygen, carbon dioxide, chlorine ions, sulfate

ions, acids, etc.). Frost damage does not occur in concrete unless it has

reached a critical level of saturation. Corrosion requires water and

oxygen, and is catalyzed by chlorine ions. Alkali-silica reaction requires

water. While in some cases the water present in the original concrete mix

particularly if the concrete does not dry adequately after curing is

sufficient to allow deterioration to proceed, in general more water from


55

the environment is needed. For deterioration of concrete in a hostile

environment, low permeability reduces the rate of deterioration, allowing

the concrete a longer service life. Unfortunately there are no simple,

widely accepted test methods for the measurement of permeability. Thus,

the data reported in this section are from a wide variety of test methods

that are not directly comparable. Also, the permeability or diffusivity of

concrete varies depending on what is moving through it–either because

of interactions with the concrete components (for example, water will

hydrate previously unhydrated cement, and chlorides can be bound by the

hydration products of C3A) or because the size of ion, atom, or molecule

affects its mobility.

Permeability is, of course, related to pore structure. Pore size is less

important than the connectivity of the pore system. Referring to the data

reported by Sellevold et al. (1982) in Section (2.3.3) above, the

improvement of pore structure attributed to the nucleation effect of the

fine particles of CaCO3 was not due to the (slight) reduction in total pore

volume, but to the refinement of the pore structure, which reduced its

connectivity.

Moir and Kelham, reporting results from the Building Research

Establishment study (1993), found that the permeability to oxygen for a

series of concretes made with cements with or without 5% or 25%

limestone was slightly reduced by the presence of limestone. Not

surprisingly, extended curing reduced the permeability significantly.

Porosity was very similar for the control and 5% limestone cements.

Water sorptivity was much the same for the control and 5% limestone

cements.

Schmidt (1992b) tested the permeability of airentrained concretes made

with Portland cement and Portland limestone cement by DIN 1048. In

general the performance of the two types of cement was similar and well

within specified limits (DIN 1045). He also determined the permeability

coefficients for a series of concretes made from the two types of cement.

In all cases the permeability coefficients for the Portland limestone


56

concretes were slightly lower than for the comparable concretes made

with Portland cement, as shown in Figure (2-15). Due to the limited

number of tests, Schmidt was not sure whether the data indicated a trend

of superior performance due to finer grinding and/or more efficient

particle packing. However, it is clear that these cements perform at least

as well as Portland cements in concrete having them same cement

content and curing, even without taking advantage of the lower water

demand to reduce the water: cement ratio.

In all cases the Portland limestone cements have lower permeabilities,

but it is not clear from the small number of tests whether this is generally

true. After Schmidt et al. 1993.

Alunno-Rosetti and Curcio (1997) presented data in table (2-29) on water

absorption of concretes made with cements with and without 20%

limestone. The authors note that there are larger differences between

cements from different plants than between cements from the same plant,

irrespective of whether limestone is used.

Fig. (2-15): Permeability coefficient of concretes made with Portland

cement (PZ) and Portland limestone cement (PKZ)

containing 13 to 17% limestone and subjected to

Wat

er/c

emen

tra

tio

Specific permeability K, 10-16 m2


57

different curing regimes.

Table (2-29): Water Absorption (UNI Standard 7699*) of Concretes


(Alunno-Rosseti and Curcio, 1997).

Plant B




Water absorption, % 4.8 4.8 4.2 4.5

Plant G




Water absorption, % 5.5 5.5 5.3 5.1

S. Tsivilis et al. (1999)2 concluded that the clinker quality affects

significantly the gas permeability and sorptivity of the limestone cement

concrete.The effect of the limestone quality on the concrete permeability

is not well established. Limestone additions can improve the permeability

properties of the concrete, especially in cements having high C3A

content. The pore size distribution, and more specifically the mean pore

size, affects the gas permeability and the sorptivity of the concrete. In

concrete containing cement with clinker of high C3A value, hydration

products precipitate on the aggregate surface but it does not affect the

permeability properties of the concrete. In any case, it is concluded that,

depending on the clinker quality and the cement fineness, limestone

cement concrete, with an optimum limestone content, can give lower gas

permeability and water absorption rate compared with pure cement

concrete.


58

S. Tsivilis et al. (2003) concluded that PLC concrete indicates

competitive properties with the OPC concrete and Concrete, based on

PLC, exhibits higher gas permeability values than the OPC concrete. The

limestone addition has a positive effect on the water permeability and the

sorptivity of concrete. Limestone content up to 15% w/w does not alter

the concrete porosity.

2.5.2.2 Carbonation

Sprung and Siebel (1991) found that in general concretes made with

Portland limestone cement (6 to 20% limestone) showed increased rates

of carbonation as compared with those made with Portland cements, even

when the strengths were the same. Tezuka et al. (1992) found the depth

of carbonation for mortars containing various quantities of limestone

comparable to those for the control Portland cement mortars for

limestone contents up to 10%.

Baron (1988) found that the depth of carbonation for standard mortars

made with 15% limestone cements was the same as for the control

mortars.

Barker and Matthews (1994) studied the durability of two series of

concretes: Series A made with constant cement content and water:

cement ratio, and series B made with constant slump and 28-day strength.

Their carbonation depth data for the Portland cement concretes and those

made with various limestone contents are presented in table (2-30). The

concretes were stored at 20°C and 65% RH. They found that regardless

of the composition of the cement, the depth of carbonation correlated

well with the strength of the concrete.

Schmidt (1992b) observed carbonation depths for concretes made with

Portland limestone cement (13% to 17% limestone) that were higher than

for comparable concretes made with Portland cement, but lower than for

concretes made with slag cement. However, he maintains that since the

field performance for slag cements has been good, this result should not

be interpreted as disadvantageous to the durability of concrete. In any


59

case the increases in carbonation depths measured after three years of

exposure were minimal. Fig. (2-16)from Schmidt et al. (1993) shows the

depth of carbonation for concretes cured in water for 6 days and then

exposed to a standard atmosphere of 65% R.H. at 20°C for three years.

These concretes were designed for constant water: cement ratio, so that

the workabilities were different.

Fig. (2-16): Carbonation of concretes made from different cements

and exposed to 20°C, 65% R.H. for three years. Water:

cement ratios were between 0.60 and 0.65 and the

cement content was between 280 and 300 kg/m3.

Limestone content of PKZ 35 was 13% to 17% (adapted

from Schmidt et al. 1993).

Time after moist storage, days

Dep

thof

carb

onat

ion

,mm


60

Table (2-30): Carbonation Depths at 90 days and 1 year, mm (Barker

and Matthews, 1994).

Cement Moist

curing

Series A

90 days

Series A

1 year

Series B

90 days

Series B

1 year

Portland 1 day 3.3 8.0 3.3 8.0

3 days 2.4 6.6 2.4 6.6

9% Limestone 1 day 3.9 7.6 4.6 8.4

3 days 3.1 6.2 3.3 6.6

15%

Limestone 1 day 6.0 9.9 3.4 6.2

3 days 5.3 9.0 2.7 5.0

24%

Limestone 1 day 6.6 11.0 3.4 6.9

3 days 6.9 9.7 2.6 6.3

Moir and Kelham (1993), reporting the results of the Building Research

Establishment study, found that carbonation depth is inversely related to

concrete strength. Tests of concretes containing 5% or 25% limestone, as

well as fly ash or slag, showed that carbonation depths have the same

relationship to concrete strength regardless of cement type. Increasing the

wet curing time from 1 to 3 days reduced the carbonation depths by

approximately 40% for all cement types.

Alunno-Rosetti and Curcio (1997) presented data in table (2-31) on

carbonation depth in concretes made with cements with and without 20%

limestone. Use of limestone in cement did not impact depth of

carbonation.


61

Table (2-31): Cabonation Depths (UNI Standard 9944*) at 900 days in


Limestone (Alunno-Rosseti and Curcio, 1997)

Plant B




Carbonation depth, mm 20 10 18 13

Plant G




Carbonation depth, mm 19 21 15 16

S. Tsivilis et al. (2000)studied the effect of adding limestone to Portland

cement in corrosion resistance, the limestone cements have been

produced by intergrinding clinker, limestone and gypsum (5% per clinker

weight), in a pro-pilot plant ball mill of 5 kg capacity. The codes of the

samples as well as their properties are given in table (2-32) The cements

LC1±LC4 contain 0%, 10%, 15%, and 20% limestone, respectively, and

have the same 28 day compressive strength (48 ± 51 N/mm2, strength

class 42.5R of prEN 197-1). The cement LC5 contains 35% limestone

(strength class 32.5R of prEN 197-1).


62

Table (2-32): Characteristics of the tested cements

Sample

Composition (%) Sp.

surf.

(cm2/g)

Compressive strength

(N/mm2)

Clinker Limestone1

day

2

days

7

days

28

days

LC1 100 0 2600 11.9 21.3 35.3 51.1

LC2 90 10 3400 11.2 20.9 36.3 47.9

LC3 85 15 3660 12.9 22.7 37.7 48.5

LC4 80 20 4700 14.9 24.3 38.0 48.1

LC5 65 35 5300 9.8 17.0 26.2 32.9

The concrete production was carried out in a mixer of 50 l capacity. The

mix proportions and the aggregate grading are given in table (2-33) The

W/C ratio was 0.50 and the calcareous sand: cement ratio was 3:1.

Prismatic specimens (80x80x100 mm) were made and four cylindrical

steel bars (12x100 mm) were embedded in each one, as shown in Figure

(2-17). Each bar has a properly attached copper wire. Both the top

surface of all specimens and the part of steel bars which protrudes over

the concrete, are covered with an epoxy glue to protect the bars from

atmospheric corrosion. The specimens were partially immersed in a 3%

wt NaCl solution, up to a height of 25 mm, in order to accelerate the

corrosion process. After immersing all specimens in the corrosive

solution mean carbonation depth, after 9 and 12 months, using

phenolpthalein indicator, sprayed across a vertical section of the

specimen. was carried out.


63

Table (2-33): Concrete mix proportions and aggregate grading

Sample W/C Cement (kg/m3) Aggregate (kg/m3)

LC1- LC4 0.70 270 1940

LC5 0.62 330 1905

Sample

Aggregate grading (%)

Size fraction (mm)

30-15 15-7 7 -3 3 -1 1-0.2 0.2-0

LC1- LC4 30 22 8 15 15 10

LC5 30 22 8 15 15 10

Fig. (2-17): Specimen's shape and dimensions (corrosion tests).

Porosity of the specimens, after 9 months exposure, using a Carlo Erba

2000 Hg porosimeter and the carbonation depth is shown in table (2-34),

all types of Portland limestone cements used had not carbonated at

exposure time of 9 and 12 months. The specimen of pure cement had

carbonation depth 3±5 mm. In addition, the specimens with limestone

had lower porosity compared with the pure cement specimen in table(2-


64

34) and the limestone additions decrease the carbonation depth and the

total porosity of the mortar.

Table (2-34): Carbonation depth and total porosity of the cement

mortars.

Sample Carbonation depth (mm) Total porosity (%)

9 months 12 months 9 months

LC1 3 5 15.3

LC2 0 0 11.6

LC3 0 0 12.2

LC4 0 0 12.5

LC5 0 0 13.1

2.5.2.3 Freeze/Thaw and Deicer Scaling

European research shows that even when the limestone content of the

cement is much higher than that proposed for ASTM C 150 cements, it is

possible to make concrete with good frost resistance. Sprung and Siebel

(1991) found that, in general, concretes made with Portland limestone

cement showed reduced resistance to frost damage as compared with

those made with Portland cements, even when the strengths were the

same. They tested Portland limestone cements containing 15% limestone

by the “cube” method. Concretes having a cement content of 300 kg/m3

and a water: cement ratio of 0.60 were wet cured for 6 days and then

moist cured for an additional 28 or 56 days. The cubes were subjected to

100 freeze/thaw cycles. Any concrete that experiences a mass loss of less

than 10% is considered frost resistant. They concluded that it is possible

to make concretes from Portland limestone cement that are as frost

resistant as comparable concretes made with Portland cement provided

the limestone meets the criteria for composition limits specified by EN

197-1, the limestone content does not exceed 20% by mass of cement,


65

and equal concrete strengths are reached. It should be noted that the most

important criterion for limestone quality as related to frost resistance is

the clay content, since clays can adsorb moisture which expands on

freezing. They consider the methylene blue test to be an adequate

measure of this tendency.

Siebel and Sprung (1991) report that the results of a European round

robin on the frost resistance of concretes made with Portland limestone

cements showed that one such cement did not provide adequate frost

resistance. Thus not all limestones are suitable for Portland limestone

cement. They studied three commercial Portland limestone cements

having 11%, 26%, and 12% limestone. They tested concretes having

different water: cement ratios for frost resistance and found that

concretes having a water: cement ratio greater than 0.60 were not frost

resistant, while those with water: cement ratios less than or equal to 0.60

were adequately frost resistant except for the cement having 11%

limestone. (They believe the limestone used in this cement was

unsuitable.) The German standard DIN 1045 specifies a maximumwater:

cement ratio of 0.60 for frost-resistant concrete.

Schmidt (1992b) tested concretes for frost resistance by the “cube”

method. The specimens made from Portland limestone cement (13% to

17% limestone) performed as well as or slightly better than those made

from Portland cement. He also tested concrete specimens for deicer

scaling according to Austrian Standard 3303, in which concrete slabs are

ponded with a salt solution and subjected to 70 freeze/thaw cycles. The

specimens had air contents of 4% to 5% by volume. The performance of

the specimens made with the Portland limestone cement was similar or

even slightly better than those made with Portland cement.

Albeck and Sutej (1991) report that experiments performed by the study

group on interground materials at the VDZ (German Cement Works’

Association) showed that the frost resistance of concretes made from

Portland limestone cements is the same as for Portland cement provided


66

that the organic material content of the limestone is less than 0.20% by

mass as measured by total organic carbons.

Figure (2-18) from Schmidt et al. (1993) shows how the quality of

limestone can affect the frost resistance of concretes made with Portland

limestone cements with limestone contents of 13% to 17%. Portland

limestone cements were made using different limestones to the same

strength class (32.5 MPa). In all cases but one, the Portland limestone

cement concretes performed as well as the Portland cement concrete. The

one exception, F1, did not conform to the requirements of EN 197.

Figure (2-19) shows the results of cube tests for concretes made with

Portland limestone cement were better than for companion specimens

made with Portland cement, but all concretes had mass losses

significantly lower than the 10% maximum limit. In these tests the water:

cement ratio was 0.60, which is higher than recommended by ACI for

concretes exposed to a hostile environment.

Baron (1988) found that tests of frost resistance performed at different

laboratories yielded conflicting results. A new approach which was just

then being tested in the laboratory involved determining the required air

void spacing factor for mortars made with different cements individually,

rather than prescribing the same spacing factor for all cements.

Preliminary data suggested that 15% limestone cements require smaller

spacing factors than Portland cements in order to provide good frost

resistance.


67

Fig. (2-18): Effect of type of limestone on frost resistance of concrete.

Portland limestone cements of class 32.5 were produced

from the same clinker, but with different types of

limestone in amounts of 13% to 17%. In most cases the

frost resistance is comparable to that of the Portland

cement (after Schmidt et al. 1993).

Klieger (1985) reports the results of deicer scaling tests(ASTM C 672)

after 300 cycles for air-entrained concretes made with six cements: Two

with no limestone, two with 3% interground limestone, and two with 3%

blended limestone. The cements with interground limestone performed

equal to or better than the cements with no limestone, while for the

blended limestone cements, one performed slightly better and one

slightly worse.

Wei

ght

loss

, %

Freeze/ thaw cycles


68

Fig. (2-19): Results of “cube” tests for the frost resistance of

concrete.Mass loss of less than 10% is considered

acceptable. Here the Portland limestone cements, PKZ 35

F (with limestone contents of 13% to 17%), performed

better than the companion Portland cements, PZ 35 F

(adapted from Schmidt et al. 1993).





samples as well as their properties are given in table (2-32), The cements




(strength class 32.5R of prEN 197-1).

The concrete production was carried out in a mixer of 50 l capacity. The

mix proportions and the aggregate grading are given in table (2-33), The

W/C ratio was 0.50 and the calcareous sand:cement ratio was 3:1.

Wei

ght

loss

aft

er 1

00 c

ycle

s, %


69







wtNaCl solution, up to a height of 25 mm, in order to accelerate the


solution mean carbonation depth, after 9 and 12 months, using

phenolpthalein indicator, sprayed across a vertical section of the

specimen. was carried out.

and the carbonation depth is shown in table (2-34), all types of Portland

limestone cements used had not carbonated at exposure time of 9 and 12

months. The specimen of pure cement had carbonation depth 3±5 mm. In

addition, the specimens with limestone had lower porosity compared

with the pure cement specimen in table (2-34) and the limestone

additions decrease the carbonation depth and the total porosity of the

mortar.

2.5.2.4 Sulfate Resistance

Soroka and Stern (1976) studied the effect of reagent-grade CaCO3 and

CaF2 (used as an inert filler) on the sulfate resistance of Portland cement

mortars having a water: cementratio of 0.75. Specimens 25.4x25.4x

158.7 mm in size were immersed in a 5% Na2SO4 solution. Their time to

cracking data are shown in table (2-35) It can be seen that the CaCO3 has

a beneficial effect beyond the reduction of the C3A content of the cement.

Soroka and Setter (1980) followed up this preliminary study by

examining the expansion and deterioration of mortars containing various

amounts of ground limestone, dolomite, or basalt and immersed in 5%

Na2SO4 solution for up to 11 months. The additive contents were 10%,

20%, 30%, and 40% by mass. They found that the limestone imparted

some improvement in sulfate resistance as compared with the control.


70

The fineness of the additive was also significant, as can be seen in table

(2-36). However, they found that after long periods of exposure the

intensity of cracking of the limestone-filled mortars was essentially the

same as for the others. Thus they conclude that the use of limestone

improves the sulfate resistance of mortars, but not to such an extent as to

produce sulfate resistant mortars.

Table (2-35): Time to Cracking for Mortar Prisms Exposed to 5%

Na2SO4 (Soroka and Stern, 1976).

Mortar Time to

cracking, weeks

28-day compressive

strength, MPa

Reference 6 25.3

10% CaCO3 10 27.0

20% CaCO3 12 29.3

30% CaCO3 14 29.7

40% CaCO3 16 30.9

10% CaF2 6 23.7

20% CaF2 6 28.2

30% CaF2 6 32.6

40% CaF2 6 28.9

Hooton (1990) tested pairs of commercially produced cements made

from the same clinker with and without limestone. Both ASTM C 452

and C 1012 were used. In ASTM C 452, the SO3 content is raised to

7.0% using gypsum and the mortar bars are stored in water while

expansions due to the internal sulfate attack are measured. In ASTM C

150 the 14-day expansion limit for sulfate resistant cement is 0.040%,

while in CSA/CAN-A5 the limit is 0.035% for sulfate resisting cement

and 0.050% for moderate sulfate resisting cement. Hooton’s data are

shown in table (2-37). There is no clear trend with regard to effect of


71

carbonate on sulfate resistance. Cements 2, 2c, 3, and 3c meet the CSA

criterion for moderately sulfate resisting cement.

In ASTM C 1012, which was developed for the evaluation of blended

cements, mortar bars are exposed to 5% Na2SO4 solution once

companion cubes have reached a compressive strength of 21 ± 1 MPa.

Tentative expansion limits for this method are 0.10% at 6 months for

moderate sulfate resisting cement and 0.05% at 6 months or 0.10% at 12

months for highly sulfate resisting cements. Hooton reported expansion

data up to 365 days for the six cements. The time to reach 0.10%

expansion is given in table (2-38). Again, there is no clear trend as to the

effect of carbonate use on sulfate resistance. Hooton concluded that

sulfate resistance is not affected by carbonate and is primarily determined

by C3A content.

Gonzáles and Irassar (1998) also evaluated effects on sulfate resistance

(ASTM C 1012) of mortars made with Type II and Type V cements with

0%, 10%, and 20% limestone. Their results indicate no significant

difference in sulfate resistance of low-C3A cements with or without 10%

limestone; however, for 20% replacement levels, the sulfate resistance

was lowered. Their results are summarized in table (2-39).

Table (2-36): Time to Cracking for Mortar Prisms Exposed to 5%

Na2SO4with 30% Filler, Weeks (Soroka and Setter,

1980)

Fineness, m2/kg Limestone Dolomite Basalt

115-130 12 12(?) 4

370-300 10 6 4

660-710 10 6 4

960-1120 18 6 2

Reference 6 weeks


72

Table (2-37): ASTM C 1012: Time to 0.10% Expansion (Hooton

1990)


% C3A 10.4 10.0 9.1 9.8 8.3 7.3

% CaCO3(by

TGA) 0.3 4.1 0.8 4.7 0.3 2.6

Time to 10%

expiations, days 117 142 167 161 196 236

Table (2-38): ASTM C 452 Expansions, % (Hooton 1990)


% C3A 10.4 10.0 9.1 9.8 8.3 7.3

% CaCO3(by

TGA) 0.3 4.1 0.8 4.7 0.3 2.6

Age, days

14 0.054 0.058 0.036 0.041 0.039 0.036

28 0.071 0.092 0.053 0.054 0.051 0.043

56 0.084 0.126 0.066 0.058 0.058 0.050

91 0.086 0.142 0.075 0.058 0.061 0.054

105 0.088 0.144 0.077 0.059 0.062 0.055

119 0.088 0.145 0.079 0.059 0.062 0.056

170 0.087 0.146 0.079 0.059 0.064 0.056

261 0.088 0.148 0.079 0.059 0.065 0.057

365 0.090 0.150 0.080 0.060 0.068 0.060


73

Table (2-39): Sulfate Resistance in ASTM C 1012 Mortars (Gonzáles

and Irassar, 1998)

Cement Type V Type V

C3A content, %by mass 0 1

C3S content, % by mass 40 74

Limestone replacement 0 10 20 0 10 20

Time to 0.10% Expansion,

days 1260 857 208 148 164 92

Reduction in compressive

strength (1 year in sulfate

solution), %

3 4 5 29 17 50

Cement Type II

C3A content, %by mass 6

C3S content, % by mass 51

Limestone replacement 0 10 20

Time to 0.10% Expansion,

days 165 209 108

Reduction in compressive

strength (1 year in sulfate

solution), %

8 25 40

Marsh and Joshi (1986) studied the effects of large quantities (30% and

50%) of limestone on the sulfate resistance of concrete. In their work

limestone was added to cement paste rather than to the cement, since the

Canadian standard limits the limestone content of cement to 5%, but

allows additional amounts to be used in concrete. Specimens were cast

and sealed in plastic molds 25x25x300 mm and were rotated until set.

After 24 hours they were demolded and cured in saturated limewater for

28 days at either 20°C or 50°C. The specimens were cut to size at age 7


74

days. The resistance to sulfate attack was determined by measuring the

length change of 125 mm cement paste prisms immersed in 0.35 M

Na2SO4 solution at 20°C. The pH of the solution was maintained at

approximately 7 by the addition of 0.5 M H2SO4 as needed. At these

dosages the use of limestone resulted in increased expansions due to

sulfate attack. However, in the specimens cured at 50°C all of the pastes

were resistant to sulfate attack for exposure periods in excess of one year.

Matthews reports that in the Building Research Establishment study

(1993) no relation was found between limestone content and sulfate

resistance of concretes. The C3A content of the parent cement determined

the sulfate resistance.

Taylor (2001a, b) studied effects of use of limestone in low-C3A content

Portland cements on sulfate resistance. In one study (Taylor 2001a), a

clinker with C3A content of 8% was interground with one of two

limestones: One limestone was interground at either 2.5 or 3.5%, while

another was interground in amounts of 3.0% and 5.0%. Both ASTM C

1012 and C 452 data indicated acceptable (per ASTM C 150, C 595, or C

1157) performance for all cements. Data are summarized in Figures (2-

20) and (2-21). In another study, Taylor (2001b) evaluated two cements

with C3A contents of 3% and 5% interground with limestone in amounts

of 4.0% and 3.5%, respectively. Results of ASTM C 452 and C 1012

testing demonstrated acceptable performance according to cement

specifications (ASTM C 150, C 595, or C 1157). Expansion data are

plotted as a function of time in Figures (2-22) and (2-23).


75

Fig. (2-20): Expansion in test method ASTM C 1012 (after Taylor

2001a) for Type II cements with two levels of 2 different

limestones.

Fig. (2-21): Expansion in test methods ASTM C 452 (after Taylor

2001a) for Type II cements with two levels of 2 different

limestones.

Exp

ansi

on, %

Age, days

Exp

ansi

on, %

Age, days


76

Fig. (2-22): Expansion in test method ASTM C 1012 test for cements

withC3A contents of 5% or less. Cements A3 and B3 were

interground with 3% limestone (after Taylor 2001b)

Fig. (2-23): Expansion in test method ASTM C 452 for cements with

C3A contents of 5% or less. Cements A3 and B3 were

interground with 3% limestone (after Taylor 2001b).

Exp

ansi

on, %

Age, days

Age, days

Exp

ansi

on, %


77

K.K. Sideris et al. (2006) find that Usingpozzolanic admixtures increased

in most cases the sulfate resistance of the blended cements. As the

pozzolan content increased, the sulfate resistance also increased, even

with somewhat higher w/binder ratio used in his research. Lignite fly

ashes, with high CaO and SO3 content may have a positive effect on the

sulfate resistance of blended cements. Specimens containing PFA fly ash

blended cements gave the smallest expansion among all cement mixtures

tested in this research and developed high compressive strength from

early ages. These specimens also gave the least reduction in compressive

and flexural strengths due to sulfate attack. On the other hand specimens

containing MFA fly ash blended cements gave the worst performance

since they were very fast totally deteriorated. The two examined lignite

fly ashes had similar chemical composition but they had totally different

performance regarding the sulfate resistance of the mixtures. This

indicates that is the mineralogical composition what really counts and

makes the difference. Carbonation depth of blended cement mixtures at

any age was greater than that of the control Portland cement mixture. On

the other hand, the rate of carbonation of the Portland cement mixture

was greater than that of blended cement mixtures, due to the formation of

secondary C–S–H and reduction in the pore structure. Among all

mixtures tested, PFA fly ash blended cements gave the lowest

carbonation rate. Among the pozzolanic materials tested in this research,

PFA had the best total performance. It is suggested that 50% PFA

blended cements may be used instead of Portland cement for the

construction of sulfate resistant concrete structures with almost equal

compressive strength. Although in this case the carbonation rate was very

slow, extra protection against carbonation should be taken at early age by

means of extended curing period until the hydration will progress and the

diameter of the pores will be therefore reduced.

S.U. Al-Dulaijan et al. (2003) studied Concrete deterioration due to

sulfate attack is the second major durability problem, after reinforcement

corrosion. This type of deterioration is noted in the structures exposed to


78

sulfate-bearing soils and groundwater. Though concrete deterioration due

to sulfate attack is reported from many countries, the mechanisms of

sulfate attack have not been thoroughly investigated, particularly the

effect of sulfate concentration and the cation type associated with the

sulfate ions on concrete deterioration. This study was conducted to

evaluate the performance of plain and blended cements exposed to

varying concentrations of sodium sulfate for up to 24 months. Four types

of cements, namely Type I, Type V, Type I plus silica fume and Type I

plus fly ash, were exposed to five sodium sulfate solutions with sulfate

concentrations of 1%, 1.5%, 2%, 2.5% and 4%. These concentrations are

representative of the sulfate concentration in highly saline soils. The

sulfate resistance was evaluated by visual examination and measuring the

and reduction in compressive strength. The maximum deterioration, due

to sulfate attack, was noted in Type I cement followed by silica fume and

Type V cements. The performance of Type V, Type I plus silica fume

and Type I plus fly ash was not significantly different from each other.

The enhanced sulfate resistance noted in the Type I cement blended with

either silica fume or fly ash indicates the usefulness of these cements in

both sulfate and sulfate plus chloride environments. Significant

deterioration was noted in the Type I cement mortar specimens, while it

was marginal in Type V and silica fume cement mortar specimens.

Deterioration in the Type I cement was manifested in the form of cracks

while etching of the surface skin was noted in Type V cement and Type I

cement blended with silica fume. No deterioration of any sort was noted

in Type I cement blended with fly ash. The maximum strength reduction,

due to sulfate attack, was noted in Type I cement mortar specimens while

it was the lowest in Type V cement mortar specimens. The reduction in

strength in the silica fume and fly ash cement mortar specimens was not

significantly different from that of Type V cement. The strength

reduction in Type V cement and Type I cement blended with either silica

fume or fly ash increased with the concentration of the sulfate solution

while the sulfate concentration had an insignificant effect on Type I


79

cement mortar specimens. Since the performance of Type I cement

blended with either silica fume or fly ash was similar to Type V cement,

it is recommended to utilize blended cements in concrete to improve the

concrete durability in terms of both sulfate attack and reinforcement

corrosion.

The maximum deterioration was noted in the Type I cement mortar

specimens. As shown in Figure (2-24), the strength reduction in Type I

cement after 24 months of exposure was almost similar for all the sulfate

concentrations.

Fig. (2-24): Comparison of reduction in compressive strength in the

mortar specimens exposed to varying concentrations of

sodium solution for 24 months.

Red

uct

ion

in c

omp

ress

ive

stre

ngt

h, %


80

2.5.2.5. Thaumasite

Formation of thaumasite, a calciumsilicate- sulfate-carbonate mineral

(CaSiO3.CaCO3. CaSO4.15H2O), has relatively recently received

attention as a potential deterioration mechanism. The mere presence of

thaumasite in a concrete or a deteriorated concrete is not sufficient to

implicate it as a cause of problems. In the relatively few cases of

thaumasite sulfate attack, several factors have been common (Hooton and

Thomas, 2002), including presence of sulfate and/or sulfides in the

ground, mobile groundwater, carbonate sources (usually limestone

aggregate), and low temperatures, generally below 15°C. (Some

researchers use 0 to 5°C as a more typical temperature range, for

example, Bensted 1999.) However, Hooton and Thomas (2002) reviewed

published literature on thaumasite sulfate attack and concluded:

Field experience with up to 5% limestone in Portland cement in Canada

and Europe for over 20 years has not produced any known cases where

this has contributed to thaumasite sulfate attack. Based on the literature

reviewed, there does not appear to be any significantly increased

susceptibility to sulfate attack with respect to use of up to 5% limestone

in Portland cements. Research does exist concerning much higher levels

of limestone (15% to 35%, or where the carbonate fines originate from

the aggregate), where used in cold temperatures combined with wet and

aggressive sulfate environments, that indicates more susceptibility to the

thaumasite form of sulfate attack. Overall, the data available support use

of up to 5% limestone in Portland cements.

G. Kakali et al.(2003) used three types of cement: (i) OPC, (ii) Portland

limestone cement containing 15% w/w limestone and (iii) Portland

limestone cement containing 30% w/w limestone. Mortar specimens

were prepared using calcareous and siliceous sand. The specimens were

immersed in a 1.8% MgSO4 solution and cured at: (i) 5oC and (ii) 25 oC.

The formation of thaumasitewas checked and confirmed by XRD and

TGA. In addition visual inspection, strength tests and ultrasonic pulse

velocity measurements were carried out for several months. It is


81

concluded that mortars containing limestone, either as sand or as a main

constituent of the cement, suffer from the thaumasite form of sulfate

attack at low temperature. At room temperature, no sulfate attack was

observed after a year of exposure and the compressive strength of the

specimens was measured after 28 days and after 9 months of exposure in

MgSO4 solution in order to investigate the effect of the sulfate attack on

the strength loss of the samples, table (2-40) shows the composition and

fineness of the cements used

A visual inspection of the specimens was carried out monthly. The

remarks are summarised in table (2-41). Photos of specimens stored in

the sulfate solution for 11 months are presented in Figures (2-25) and (2-

26). The samples stored at 5o C showed the first signs of deterioration

after 8 months of exposure while the specimens stored at 25o C did not

show any clear evidence of sulfate attack up to 11 months. The

discussion below concerns the samples stored at 5o C.

Indications of initial deterioration were first observed on the surface of

sample LC2 after 8 months of exposure. A longer time was required for

samples LC1, PC-c and PC-s, in ascending order. In all cases, the first

sign of attack was the deterioration of the corners followed by cracking

along the edges. Progressively, expansion and spalling took place on the

surface of the specimens. The surface of the cracks was covered with a

white soft substance. As can be seen, from Figure (2-25), the damage due

to sulfate attack was greater the higher the limestone content in the

cement. However, even the presence of calcareous sand caused visible

damage in the Portland cement samples without any limestone additions,

that was not evident in the PC-s control sample. In the presence of 15%

and 30% limestone filler, there was no apparent difference in the extent

of damage between samples with siliceous and calcareous sand. And the

28 day compressive strength, prior to any exposure to sulfates, is shown

in Figure (2-27). It is seen that mortars made with calcareous sand show

higher strength than the mortars made with siliceous sand. After 9

months exposure to the MgSO4 solution at 5o C, a significant loss of


82

strength was observed Figure (2-27). More specifically, in the case of

siliceous sand, the loss of strength was 8% of the 28 day strength for the

Portland cement (PC), 18% for the limestone cement containing 15%

limestone (LC1) and 34% for the limestone cement containing 30%

limestone (LC2). In the case of calcareous sand the loss of strength is

greater 27%, 21% and 36% of the 28 day strength for the samples PC,

LC1 and LC2 respectively. These results show that the cementitous

limestone content as well as the use of calcareous sand negatively affects

the resistance of the cements against sulfate attack at low temperatures.

Concerning the specimens cured at 25oC, their compressive strength has

increased in most samples. There may be a slight strength loss in the

sample PC-s. The long term curing of the specimens will provide more

data concerning the effect of the sand on the sulfate resistance of the

mortars at 25 oC.and the conclusions are :

• Mortars containing limestone, either as sand or as main cementitous

constituent, are susceptible to the thaumasite form of sulfate attack at low

temperature.

• The rate of thaumasite formation is greater, the higher the limestone

content.

• Calcium hydroxide is a reactant, rather than a product of reaction,

during sulfate attack of cement at 5oC. Thaumasite formation is

accompanied by the formation of brucite and secondary gypsum.

Table (2-40): Composition and fineness of the cements used.

Code Synthesis of cements

Specific

surface

(cm2/g)

PC Clinker: 100% w/w (gypsum: 5% of clinker

by mass)

3030

LC1 Clinker: 85% w/w, limestone 15% w/w

(gypsum: 5% of clinker by mass)

3950

LC2 Clinker: 70% w/w, limestone 30% w/w

(gypsum: 5% of clinker by mass)

5170


83

Table (2-41): Appearance of specimens, stored in 1.8% MgSO4

solution at5 oC.

Age,

(months) PC-s

PC-c

LC1-c

LC1-s

LC2-c

LC2-s

7 No visible

deterioration

No visible

deterioration

No visible

deterioration

No visible

deterioration

8 No visible

deterioration

No visible

deterioration

Deterioratio

n at corners

Deterioratio

n at corners

and cracking

along edges

9 No visible

de

terioration

Some

deterioration

at

corners

Some

cracking

along the

edges

Extensive

cracking and

expansion

10 Some

deterioration

at

corners

Cracking

along the

edges

Cracking

and

expansion

Extensive

cracking and

expansion

11 Cracking

along the

edges

Cracking

and

expansion

Cracking

and

expansion

Spalling


84

Fig. (2-25): Specimens cured for 11 months in a 1.8% MgSO4 solution,

at 5oC.

Fig. (2-26): Specimens cured for 11 months in a 1.8% MgSO4 solution,

at 25oC.


85

Fig. (2-27): Effect of curing temperature on the compressive strength

of the specimens.

2.5.2.6 Chlorides

Ramachandran et al. (1990) studied mortars containing 0%, 2.5%, 5%,

and 15% precipitated CaCO3 (particle size 1 to 5 μm) or ground

limestone – (particle size 1 to 40 μm) at water: cement ratios of 0.42 and

0.60. The specimens were hydrated in limewater or in laboratory

prepared “seawater” (2.7% NaCl, 0.32% MgCl2, 0.22% MgSO4, and

0.13% CaSO4) for up to one year. They monitored length and modulus of

elasticity periodically. They found that the strengths of the mortars were

not affected by the ground limestone, but at 15% replacement,

precipitated CaCO3 reduced the strength by about 50%. When the

compressive strengths were similar, specimens at a water: cement ratio

0.60 or containing precipitated CaCO3 exhibited much higher expansions

than the controls when exposed to seawater. Only those specimens with a

water: cement ratio of 0.42 containing the ground limestone showed

similar expansions to the controls. Moduli of expansion were similar to

the control for the lower water: cement ratio mortars, except at the 15%

Sample

Com

pre

ssiv

e st

ren

gth

, MP

a


86

replacement level by precipitated CaCO3, which was much lower.

Exposure to seawater generally lowered the moduli, with more reduction

in the higher water: cement ratio mortars. The same authors (Feldman et

al. 1992) also looked at limestone Portland cement mortars exposed to

NaCl and MgCl2 solutions, concluding that the moduli are reduced and

expansions increased compared to controls exposed to Ca(OH)2 solution.

The magnitude of the changes depended on the water: cement ratio, and

the amount and fineness of the limestone used.

Deja et al. (1991) subjected mortar specimens containing 5% ground

limestone to a low pressure steam treatment (maximum temperature

80°C) followed by immersion for up to one year in a mixed salt solution

loosely based on the composition of seawater. Three types of specimens

were tested: 25 x 25 x 100 mm prisms for strength tests, cylinders with

steel bars along the axis for steel passivation studies, and 40 x 40 x 160

mm prisms with embedded steel plates for mass loss studies. Their data

on the effect of chloride exposure on the compressive and flexural

strength. Table (2-42) show that chloride exposure is equally deleterious

to the strength of mortars with or without limestone. The mass loss of the

steel plates for the control and 5% limestone specimens stored in water

for one year were 6.82 and 8.68 g/m2, respectively, while for the

specimens stored in the salt solution they were 32.51 and 7.13 g/m2,

respectively. Thus the limestone was effective in protecting the steel

from corrosion. The passivation data lead to a similar conclusion.

Tezuka et al. (1992) determined the diffusion coefficient for chloride ions

for a series of mortar specimens containing different quantities of

limestone ground to 450m2/kg. They found that the diffusion coefficients

for the control and the 10% limestone mortars were comparable (51.2 x

10-9 cm2/s and 53.1 x 10-9 cm2/s, respectively), and that for the 5%

limestone was lower (14.3 x 10-9 cm2/s).


87

Table (2-42): Strengths of Mortars Exposed to Mixed Salt Solution,

MPa(Deja et al. 1991)

Age Compressive Flexural

Control 5%

Limestone Control

5%

Limestone

Initial 41.2 42.1 8.8 8.6

56 days:

In water 47.8 47.1 11.5 11.1

In solution 45.4 42.3 11.5 12.1

365 days:

In water 49.2 47.6 11.0 11.3

In solution 36.6 36.9 10.2 8.8

Moir, reporting the results of the Building Research Establishment study

(1993), found no clear trend regarding the effect of 5% limestone on the

resistance of concrete to chloride penetration. The best predictor of

chloride ion penetration was compressive strength: The higher the

strength, the more resistant the concrete to chloride ions. However, for

concretes of the same strength class exposed to seawater for two years,

chloride concentration 30 mm from the surface increases with cement

C3A content.

Baron and Douvre (1987) state that for marine exposure, the limestone

content should be limited to 10%, based on laboratory and field tests.

They also recommend that the limestone and clinker be tested for

compatibility with each other and the environment in which the

limestone Portland cement is to be used.

Alunno-Rosetti and Curcio (1997) presented data in table (2-43) on

chloride penetration of concretes made with cements with and without

20% limestone. The authors note that there are larger differences between


88

cements from different plants than between cements from the same plant,

irrespective of whether limestone is used.

Table (2-43): Chloride Penetration (UNI Standard 7928*) of Concretes


(Alunno-Rosseti and Curcio, 1997.

Plant B




Chloride penetration, mm

at 28 days 43 102 38 48

at 60 days 63 113 49 79

Plant G




Chloride penetration, mm

at 28 days 212 197 115 146

at 60 days 281 264 183 182

2.5.2.7 Alkali-Silica Reactivity

Hobbs (1983) reported on the effects of 5% limestone on the expansion

due to alkali-silica reactivity of 25 x 25 x 250 mm mortar bars made from

Thames Valley sand and a Beltane opal rock having particles 150 to 300

μm in size. The proportion of Beltane opal was adjusted to give the

critical alkali-reactive silica ratio. The expansion at 200 days averaged

0.009% for the Portland cement specimens and 0.021% for the specimens

with 5% limestone. Times to cracking were as shown in table (2-44).


89

Hobbs concluded that although there is some effect on the average

expansion, the use of 5% limestone neither reduces the time to cracking

below the minimum observed for Portland cement mortars nor increases

the expansion at 200 days above the maximum observed for Portland

cement mortars. He therefore concludes that it does not increase the

likelihood of deleterious expansions due to alkali-silica reaction.

Table (2-44): Time to Cracking Due to ASR, Days (Hobbs 1983)

Water/solids Cement

alkalies

Portland

cement 5% Limestone

0.41 1.00% 5, 6 8, 8

0.53 1.00% 28, 39 54, 54

0.53 0.79% * *

*Italian national standard.

2.5.2.8 Corrosion





samples as well as their properties are given in table( 2-32). The cements




(strength class 32.5R of prEN 197-1).The concrete production was

carried out in a mixer of 50 l capacity. The mix proportions and the

aggregate grading are given in table (2-33)

The W/C ratio was 0.50 and the calcareous sand:cement ratio was 3:1.





90




wtNaCl solution, up to a height of 25 mm, in order to accelerate the


solution Corrosion half-cell potential vs. Saturated Calomelan Electrode

(SCE), periodically and Gravimetric mass loss of the rebars after 9 and

12 months exposure were carried out.

Figure (2-28) presents the corrosion potential vs. exposure time and

limestone content. The limestone cement specimens indicate a clear

decrease of the corrosion potential, compared to the pure cement

specimens. The potential decreas is an indirect indication that the

Portland limestone cements actually provide anti-corrosive protection.

The anti-corrosion effect is greater as the limestone content increases. As

a matter of fact, corrosion potential should be considered only as a

measure of specimen's trend for corrosion and not as an absolute measure

of corrosion itself. Figure (2-29) presents the mass loss of rebars (average

value of four specimens), expressed as mg/cm2 of surface of rebars. It is

shown that there is an explicit decrease of corrosion in specimens with

limestone. The mass loss of rebars decreases as the limestone content

increases up to 20%. The mass loss of specimens with 20% and 35%

limestone is approximately the same, in the frame of statistical

analysis.and the conclution is Portland limestone cement, containing 20%

limestone, shows the optimum protection against rebars corrosion.


91

Fig. (2-28): Corrosion potential vs. exposure time and limestone

content.

Fig. (2-29): The effect of the limestone content on the mass loss of

rebars.

Time, days

Pot

enti

al, m

V

Limestone content, %

Mas

s lo

ss o

f r

ebar

, mg/

cm2


92

2.5.3 Interactions with mineral and chemical admixtures

Chemical admixtures (water-reducing, air entraining, accelerating, and

retarding admixtures) are an important part of concrete manufacture and

can directly affect both short and long term properties. Mineral

admixtures (also known as supplementary cementing materials, or

SCMs), including silica fume, blast furnace slag, fly ash, and other

pozzolans, have likewise become important components of blended

cements for the properties they enhance. The performance of some of

these materials in Portland cements with limestone has recently been

investigated by Detwiler (1996) and Nehdi, Mindess, and Aïtcin

(1996ab).

Detwiler (1996) has reported the results of concrete strength tests using

two cements ground from the same clinker at the same plant: A Type I

containing no limestone and a Type 10 that had 2.5% by mass limestone

interground. Both water-reducing and air-entraining admixtures were

used. For the Type 10 cement concretes, slightly more air entraining

admixtures were required. The compressive strengths of concretes tested

with and without fly ash show similar results when the limestone cement

was used. The compressive strength data are shown in table(2-45)

Freeze/thaw durability was above 93% for all samples with no significant

differences between the concretes made with Type I or Type 10 cements.

Deicer scaling was comparable in the Type 10 cement concretes and

drying shrinkage was also similar in both concretes.


93

Table (2-45): Compressive Strengths of Concretes, MPa (Detwiler

1996)

Cement

Cement

content

Unit

weight 7 days 28 days 56 days

(kg/m3) (kg/m3)

Type 1 362 2270 29.4 36.1 39.5

Type 10 2305 29.4 36.7 41.1

Type 1 362 2250 22.7* 30.1 30.5

Type 10 2300 24.6* 31.7 36.5

Type 1 308 2295 18.8* 25.0 27.2

Type 10 2245 19.1* 23.9 28.2

Type 1 308 2290 23.6 30.9 30.4

Type 10 2310 23.1 30.3 29.0

*Averages of two102x203-mm cylinders at 8 days. All other values are the average of

three 102x203-mm cylinders.

Nehdi, Mindess and Aïtcin (1996ab) studied high strength,

superplasticized mortars and concretes containing Portland cement

blended with limestone and silica fume. The mortar strengths were not

affected by replacement of cement with limestone of up to 10% to 15%.

With 10% silica fume also included, higher strengths were attained after

about 7 days. For their concrete system, the 12-hour strength was

improved from less than 3MPa to about 9 MPa by substituting 10%

limestone (with no silica fume). At 7 days the strength was best at middle

levels (about 5%) of both silica fume and limestone, while at 91 days the

strength of the concretes made with 5% limestone was slightly lower than

those made without limestone.

Brookbanks, describing results from the Building Research

Establishment study (1993), reported that the amount of Vinsol resin air

entraining agent required to achieve 6.0±0.5% air in fresh concrete was


94

the same, 1.1 ml/kg cement, for the cements with 0% and 5% limestone

and only slightly higher, 1.3 ml/kg cement, for the cements with 16% to

28% limestone. Only in the case of a limestone not meeting the

compositional standard of EN 197 was the required amount of admixture

much higher (2.5 ml/kg cement).

Gartner (1996) reports that a proprietary additive improves the

performance of Portland cements and Portland-limestone blended

cements by complexing the iron in the C4AF and allowing a carbonated

AFm phase to form more readily. This leads to enhanced hydration for

the other phases (as an iron bearing precipitate does not form on the

surface of the hydrating grains, hindering their reaction) as well, leading

to higher strengths. In Portland cement containing limestone, the

enhancement is generally better, as shown in the table (2-46) Each “run”

in the table represents a different clinker and compares the additive to an

additive-free control sample.

Table (2-46): Relative Strengths with Additive* (Gartner 1996)

Number

of runs

Limestone

content

Percentage of runs where strength increase

exceeded 5%

at 1 day at 28 days

36 0-5% 39 30

21 4-12% 65 59

3 20-25% 0 80

* Added in amounts of 400 g/t.

2.6 Specifying and Monitoring Quality

2.6.1 Limestone

Sprung and Siebel (1991) point out that since pure dense limestone

consisting primarily of calcite is not normally available for industrial

grinding in cement plants, certain minimum requirements must be

stipulated for its composition, and maximum limits put on its quantity in


95

cement. Natural limestones contain clay minerals, which above a certain

proportion can increase water demand and significantly reduce the frost

resistance of concrete. The CSA standard (CSA 1998) for Portland

cement, CAN/CSA-A5, allows a maximum of 5% limestone in normal

Portland cement, Type 10, and high-early-strength Portland cement, Type

30. Such limestone must be of a quality suitable for the manufacture of

Portland cement clinker, but no specific limits on composition are given.

The European standard, EN 197-1, allows CEM I Portland cement to

contain up to 5% minor additional constituents (MAC), of which

limestone is one possible material. The requirements for minor additional

constituents only that they do not detract from performance: Fillers are

specially selected, natural or artificial inorganic mineral materials which,

after appropriate preparation, on account of their particle size

distribution, improve the physical properties of the cement (such as

workability or water retention). They can be inert or have slightly

hydraulic, latent hydraulic or pozzolanic properties. However, no

requirements are set for them in this respect. Fillers shall be correctly

prepared, i.e. selected, homogenized, dried and comminuted depending

on their state of production or delivery. They shall not increase the water

demand of the cement appreciably, impair the resistance of the concrete

or mortar to deterioration in any way or reduce the corrosion protection

of the reinforcement. European Portland limestone cement can contain up

to 35% ground limestone. In this case, with the limestone constituting a

larger proportion of the cement, EN 197 specifies limits on the

composition of the limestone: CaCO3 content ≥75% by mass Clay

content (EN 933-9) ≤1.20 g/100 g Total organic carbon ≤0.20% by mass

for class L (prEN 13639) ≤0.50% by mass for class LL Schmidt (1992a)

adds that the MgO content should be limited to 5% by mass, although

this restriction does not appear in the current version of EN 197-1. Baron

and Douvre (1987) note that the MgO limit is intended to limit the

amount of dolomite in the limestone. The clay content is determined by

prEN 933-9, “Test for geometrical properties of aggregates–Part


96

9:Assessment of fines–Methylene blue test” (CEN 1998). In this test a 10

g/l solution of methylene blue is injected in a series of 5 ml doses into the

sample beaker. After each addition of methylene blue solution, the

sample is mixed at least 1 minute and then a stain test is performed. The

stain test consists of placing a drop of the sample onto filter paper. The

test is considered positive when a halo of a persistent light blue ring of

about 1 mm forms around the central deposit. The procedure is repeated

until the end point is reached. The end point must be confirmed by

repeating the stain test at 1-minute intervals for 5 minutes without adding

more methylene blue solution, as the clay may adsorb more dye over

time. The total volume of dye solution is used to calculate the methylene

blue value to the nearest 0.1 g of dye per kilogram of sample. Sprung and

Siebel (1991) examined different limestones and their effects on the

performance of cement. These limestones contained different proportions

of clay minerals. They found that montmorillonite has about eight times

the absorptive capacity of illite, while kaolinite has only about half that

of illite. Thus the methylene blue test does not measure clay content per

se, but the absorptive capacity of the clay component of the limestone.

For the purposes of determining the suitability of a limestone for use in

cement, this measure is actually more appropriate. In their studies of the

frost resistance of concrete, they found that the EN 197 criteria for

limestone composition are suitable for evaluating limestone for use in

Portland limestone cement. However, they found a few borderline cases

in which reliability would have beenimproved by raising the minimum

CaCO3 content from 75% to 80% by mass. In the Building Research

Establishment study (1993), some testing was done with a limestone that

did not meet the EN 197-1 criteria: Its methylene blue sorption value was

2.7 g/100 g (as opposed to the specified limit of 1.20), its total organic

carbon content was 0.38% (specified limit 0.20%), and its CaCO3

concentration was lower than the minimum specified.

Figure (2-30) shows the water: cement ratio needed to achieve a given

slump in concretes made with different cements, each made with or


97

without its own limestone. Comparison of the water: cement ratios for

0% and 5% limestone contents shows that the poor quality limestone did

not affect the water demand for the 5% limestone cement even though it

had a deleterious effect on the water demand when the limestone content

exceeded 16%.

Fig. (2-30): Pozzolanic cement market share in Italy Required water:

cement ratio to achieve a slump of 60 to 70 mm concretes

made with different cements. Cement E contained a

limestone not conforming to the EN 197-1 criteria.

Comparison of the water: cement ratios for 0% and 5%

limestone contents shows that the poor quality limestone

did not affect the water demand for the 5% limestone

cement, but had a deleterious effect on the water demand

when the limestone content exceeded 16% (after

Brookbanks 1993).


Wat

er/ c

emen

t ra

tio


98

2.6.2 Cement with limestone

Livesey (1991a) points out the need to consider the suitability of the

limestone and the composition and fineness of the cement in order to

achieve optimum performance. Sprung and Siebel (1991) determined that

it is possible to make concretes with Portland limestone cement that have

the same frost resistance as concrete made with Portland cement,

provided that the limestone meets the EN 197 criteria, that the limestone

content of the Portland limestone cement does not exceed 20% by mass

of cement and that the Portland limestone cement reaches the same

strength as the Portland cement.Yellepeddi et al. (1993) describe a test

method that can be used to determine the limestone content of cement for

the purposes of quality control. They consider X-ray fluorescence to be

less than adequate because it is not directly correlated to a phase such as

CaCO3. Instead it gives only the total carbon concentration. In addition,

Xray fluorescence analysis of carbon is subject to several difficulties:

• The fluorescence yield of light elements such as carbon is poor, and the

carbon fluorescence escapes from only a very thin layer at the sample

surface, the rest being absorbed by the sample matrix. Thus the measured

value represents only a small part of the sample.

• Surface contamination and materials used in the preparation of the

sample can affect the results because of their own carbon content.

• When carbon is measured by X-ray fluorescence, all errors are

multiplied by a factor of eight when converting to limestone

concentrations. However, quantitative X-ray diffraction can analyze the

CaCO3 content directly. X-ray diffraction has the additional advantages

of representing a larger portion of the sample (due to the high energy of

the X-rays) and being insensitive to surface contamination or the

presence of materials used in sample preparation. They developed

calibration curves based on the CaCO3 peak intensities in sets of white

and gray cement standards and found standard errors of estimate of

0.17% and 0.08%, respectively. They also found that repeated analyses

of the same standard over time were quite stable. Should peak positions


99

and backgrounds change due to sensitivity to such parameters as grain

size and matrix effects, peak search and peak integration can be used to

provide an accurate analysis. Particle size distribution can be monitored

by sieving a sample of cement and analyzing the separate fractions in

order to determine how much limestone and how much clinker are in

each fraction. Ménétrier-Sorrentino (1988) found such techniques to be

useful in her studies. Since the compositions of the limestone and clinker

are known, it is possible to do such a separation after the fact. Hawthorn,

reporting in the Building Research Establishment study (1993) on the

experience with composite cements in France, addresses the concern that

limestone-filled cements might be of less consistent quality than other

cements. He maintains that the quality of limestone cements is actually

quite uniform over time, particularly in comparison to that of cements

containing fly ash or slag. Selection of the parts of a quarry that provide

consistent material, and a large supply of material in the quarry, allow a

uniformity of raw material that is much greater than for industrial

byproducts such as slag or fly ash.

Moir (1995) also points out that the limestone content can be adjusted to

give more uniform strengths.

Although ASTM cement standards specify only minimum strength limits,

cement companies could set their own targets for strengths and use

limestone to maintain their cement strengths, producing a more uniform

product than they can without the use of limestone. Indeed, data

summarizing two years worth of grab samples shipped from a modern

cement plant producing cements both with and without limestone from

the same clinker table (2-47) shows that a similar level of quality control

on both cements can be achieved, as evidenced by the similar spread in

the chemical and physical data (Helinski 1996).


100

Table (2-47): Production Data for Cements With and Without

Limestone (Helinski 1996)

Number of samples

Type I Cement

Type 10 Cement with limestone

250+ 75

Mean Standard deviation

Mean Standard deviation

LOI 1.4 0.2 2.2 0.1

SiO2 20.03 0.23 19.98 0.22

Fe2O3 2.00 0.08 1.96 0.08

AL2O3 5.96 0.12 5.23 0.14

CaO 62.54 0.26 62.22 0.26

Free lime 1.17 0.30 1.05 0.29

MgO 2.62 0.08 2.62 0.08

SO3 4.10 0.15 4.13 0.17

K2O 1.08 0.03 1.09 0.02

Na2O 0.28 0.01 0.28 0.02

Blaine (m2/kg) 377 10 384 10

% Passing 45μm 95.6 13 93.8 1.4

Flow 121 6 120 5

Compressive strength (MPa)

3 days 27.1 1.5 27.4 1.4

7 days 34.2 1.5 34.1 1.4

28 days 42.1 1.8 42.0 1.8


101

2.6.3 Concrete

Concrete strength is a major factor in the prediction of its performance.

The type of cement is not significant with regard to strength gain except

as it relates to the amount required to obtain the strength needed (Livesey

1991a). Barker and Matthews (1994) examined the criteria specified in

the European standard for concrete, EN 206, which provides maximum

water: cement ratios and minimum cement contentsfor concrete that will

be exposed to various environments. They believe that while

water:cement ratio may be an appropriate criterion for use with a given

cement type, concrete strength should also be specified when the

standard is to apply to many types of cement. They tested two series of

concretes made with a range of cements including slag, fly ash, and

limestone–one with equal cement contents and water: cement ratios, and

the other with equal strength grade and workability. They measured

permeability, carbonation, and frost resistance in order to assess the

durability of these concretes. They found that carbonation depths at one

year ranged from 1.0 to 15.7 mm for the equal water: cement ratio

concretes and from 0.9 to 11.4 mm for the equal strength concretes.

Similarly, the permeability to oxygen was quite variable among the

concretes having the same water: cement ratio, but much the same–and

lower–among those designed to have the same strength. Frost resistance

also correlated much better with concrete strength than with water:

cement ratio. They observe that one reason for the poor correlation

between durability characteristics and water: cement ratio may be that

with cement containing secondary components, there is a question as to

what constitutes “cement”. EN 206 treats all cements equally, although if

the separate components are added at the concrete mixer the standard

takes a different view of the cementitious value of the secondary

components. They recommended adding the strength criterion to the

specification.


102

2.7 Needed Research

It is needed to explore performance in both short-term and long- term

with the following major objectives: cement type influence compared

with ordinary Portland cement, cement content, effect of mineral and

chemical admixtures and change of water: cement ratios.

`

103

CHAPTER 3

RESEARCH PROGRAM

3.1 Introduction

As presented earlier in Chapter 2, the literature review has argued that

the Portland limestone cement (PLC) is environmental friendly and its

performance is good in both short-term and long- term. Although the

local building authority prevents the use of it in the reinforced concrete,

this research has been initiated to explore the long-term performance of

the concrete manufactured from locally produced PLC and local

available common aggregate to judge its performance under local

environmental condition.

In this chapter, the objectives, scope, and details of the experimental

program are presented.

3.2 Scope

The scope of this research is limited to the concrete under normal

weather condition produced from:

Portland limestone cement,

fine aggregate: sand,

coarse aggregate: dolomite.

3.3 Objectives

The main objective of this research is to explore the performance in both

short-term and long-term with the following major variables: cement type

influence compared with ordinary Portland cement, cement content,

effect of mineral and chemical admixtures and the change of water/

Cement (W/C) ratios.

Chapter 3 Research program

`

104

To achieve the previously mentioned objectives, the current research

program has been investigated.

3.4 Variables considered

A total of 14 different concrete mixes were considered in the

current research, the variables considered are:

limestone content in cement: 0-5%, 6-20%, 21-35% with different

compressive strength grades (32.5,42.5).

Cement content: 300, 350, 400, and 450 kg/m3.

Water/ Cement (W/C) ratio.

Additivies from mineral admixtures: without mineral admixtures,

fly ash with 30% replacement, silicafume with 8% replacement.

Adding chemical admixtures: with and without high range water

reducer (solution with 1.75% by weight).

Details of the variables considered are shown in table (3-1).

3.5. Mix proportions

The mix proportions have been determined using the absolute volume

method taking into consideration the properties of concrete aggregate

used and variables considered in the previous section. Table (3-2) shows

the mix proportions.

3.6 Properties considered

The following concrete properties were determined in order to explore

the effect of studied variables:

Compressive strength for 158 mm length cube at ages of 3, 7, 28,

65, 91, 365 and 540 days.


`

105

Corrosion resistance as measured by accelerated corrosion cell for

cylindrical concrete specimens with reinforcement bar in the

centre (lollypop specimen).

Sulfate resistance for 100 mm length cube concrete specimens

estimated by the calculation of strength reduction and loss of

weight after submerging in sulfate solution. also for 285*25*25

mm mortar prisms measured by length expansion.

High temperature resistance for 70 mm length concrete cubes by

the evaluation of strength reduction after subjecting to heat at

400oC and 600oC for 3 hours. Specimens were tested directly and

after 24 hours of exposure in room temperature.

Details of test specimens and test procedures are introduced in

chapter (4).


`

106

Table (3-1): The details of the different variables considered

Mix

No.

Cement

Content

Type

of

cement

W/C

ratios

mineral

admixtures

chemical

admixtures

Type content Type content

(kg) (kg) (litre)

1 300 0.7

2 350 0.6

3 400 0.53

4 450

CEMI

32.5

0.47

5 300 0.7

6 350 0.6

7 0.53

- - - -

8 0.42 SF 30 HRWR 7

9

400

CEMI

32.5

+

CEMII/

B 32.5 0.42 FA 90 HRWR 7

10 300 0.7

11 350 0.6

12 0.53

- -

13 400

CEMII/

B 32.5

0.42

- -

HRWR 7

14 350 CEMI

42.5 0.6 - - - -


`

107

Wat

er

(lit

re)

210

168

210

210

168

210

size

2

(kg)

49

1

495

500

445

491

495

500

491

495

500

495

Coa

rse

Agg

rega

te*

size

1

(kg)

49

1

495

500

445

491

495

500

491

495

500

495

San

d*

(kg)

74

4

691

640

610

744

691

640

744

691

640

691

HR

WR

(lit

re)

- 7 7 - - 7 -

Fly

Ash

(kg)

- - 90

- -

Sil

ica

Fum

e

(kg)

- 30

- -

Cem

ent

Con

tent

(kg)

30

0

350

400

450

300

350

400

370

310

300

350

400

350

Cem

enti

tous

mat

eria

ls

Tot

al

(kg)

30

0

350

400

450

300

350

400

300

350

400

300

Cem

ent

Typ

e

CE

MI

32.5

CE

MI

32.5

+

CE

MII

/B

32.5

CE

MII

/B

32.5

CE

MI

42.5

Tab

le (

3-2)

: M

ix p

ropo

rtio

ns

Mix

.

no

1 2 3 4 5 6 7 8 9 10

11

12

13

14

108

CHAPTER 4

PROPERTIES OF MATERIALS USED AND TESTING

PROCEDURES

4.1 Introduction

As mentioned earlier in the previous chapter, the experimental program

is designed to study the long-term performance of locally produced

Portland limestone cement concrete. Properties of all materials used in

this work are presented here in this chapter.

4.2 Properties of Materials Used

4.2.1 Fine Aggregate

The fine aggregate used is natural sand composed mainly of siliceous

materials. The used sand is clean, free of impurities and with no organic

compounds.

The physical properties of sand are given in Table (4-1) and the grading

is given in Table (4-2).

Table (4-1): Physical properties of sand

Property Test result

Specific gravity 2.63

Bulk density (t/m3) 1.63

Fineness modules (F.M) 2.73

Specific surface area (S.S.A) (cm2/gm) 54.43

Table (4-2): Sieves analysis for fine aggregate

Particle size

(mm) 4.75 2.36 1.18 0.60 0.30 0.15

% Pass 99.12 96.31 87.08 53.55 15.74 6.03

Limitations* 65-100 45-100 25-80 5-48 -- -- * According to Egyptian Code of Practice (ECP- 203/2003)

Chapter 4 Properties of materials used

109

4.2.2 Coarse Aggregate

The coarse Aggregate used is dolomite. .The properties of coarse

aggregate are given in Table (4-3) and the grading is given in

Table (4-4).

Table (4-3): Physical properties of coarse aggregate

Property Test result

Specific gravity 2.5

Bulk density (t/m3) 1.54

Nominal maximum size (N.M.S) 20

Percentage of absorption 0.75%

Table (4-4): Sieve analysis for coarse aggregate

Particle size

(mm)

37.5 28 20 10 5

% Pass 100 100 94.028 37.97 2.06

Limitations* 100 100 90-100 30-60 0-10

* According to Egyptian Code of Practice (ECP- 203/2003)

4.2.3 Cementitious Materials

4.2.3.1 Cement

Four types of cement were used in the current research:

Ordinary Portland cement CEM I (32.5R) , which

contains 0-5 % limestone , produced by (source I)

Ordinary Portland cement CEM I (42.5R) , which

contains 0-5 % limestone , produced by (source II)

Ordinary Portland cement CEM I (52.5R), which

contains 0-5 % limestone, produced by (source

III)

Portland limestone cement CEM II/B (32.5R),

which contains 21-35 % limestone, produced by

(source II)


110

These four types were used as exists in its natural state. Also 3 mixtures

of CEM II/A were produced as a mixture from 2 combination forms of

cement as follows:


contain 0-5 % limestone, produced by (source I) +

Portland limestone cement CEM II/B (32.5R),

which contain 21-35 % limestone, produced by

(source II) to get CEM II /A (32.5) (50%, 50%

respectively).


contain 0-5 % limestone, produced by (source II)

+ Portland limestone cement CEM II/B (32.5R),


(source II) to get CEMII/A (32.5R) (50%, 50%

respectively).


contain 0-5 % limestone, produced by (source III)

+ Portland limestone cement CEM II/B (32.5R),


(source II) to get CEM II /A (42.5) (50%, 50%

respectively), as shown in table (4-5), The

properties of cement are given in Tables (4-6).


111

Table (4-5): Types of experimented used cements

Type of experimented used cement

Typ

e of

cem

ent

prod

uced

Fac

tory

Sym

bol

CE

MI3

2.5

CE

MI4

2.5

CE

MI5

2.5

CE

MI3

2.5

+ C

EM

II/B

32.

5 C

EM

I42.

5

+ C

EM

II/B

32.

5 C

EM

I52.

5

+ C

EM

II/B

32.

5

CE

MII

/B32

.5

OPC* Source

I

CEMI

32.5R

100

% --- --- 50% --- --- ---

OPC* Source

II

CEM I

42.5R ---

100

% --- --- 50% --- ---

OPC*Source

III

CEM I

52.5N

--- --- 100

% --- --- 50% ---

PLC**

Source

II

CEM

II/B

32.5N

--- --- --- 50% 50% 50% 100

%

*: Ordinary Portland cement

**:Portland limestone cement


112

Table (4-6): Physical properties of experimented cement

Type of experimented cement

Pro

pert

y of

exp

erim

ente

d

cem

ent

CE

MI3

2.5

CE

MI4

2.5

CE

MI5

2.5

CE

MI3

2.5

+ C

EM

II /B

32.

5

CE

MI4

2.5

+ C

EM

II /B

32.

5

CE

MI5

2.5

+ C

EM

II /B

32.

5

CE

MII

/B32

.5

Spe

cifi

cati

ons

lim

it

Initial

(min)

125 120 120 135 135 115 130 Min.

45

Set

ting

tim

e

Final

(min)

185 180 180 200 200 180 190 ---

Volume

change

(LeChatalier),

mm

1 1 1 1 1 1 1 Max.

10

2 days 19.43 22.56 24.63 20.73 23.83 23.72 --- Min

100

7 days --- --- --- 25.65 --- --- 27.66 Min

160

Com

pres

sive

Str

engt

h

(N/m

m2 )

28

days

36.66 43.1 52.97 39.82 45.31 46.69 40.89 Min

325


113

4.2.3.2 Fly Ash

Fly ash is comprised of the non-combustible mineral portion of coal.

When coal is consumed in a power plant, it is first ground to the fineness

of powder. Blown into the power plant’s boiler, the carbon is consumed

— leaving molten particles rich in silica, alumina and calcium. These

particles solidify as microscopic, glassy spheres that are collected from

the power plant’s exhaust before they can "fly” away hence the

product’s name: Fly Ash.

Chemically, fly ash is a pozzolan. When mixed with lime (calcium

hydroxide), pozzolans combine to form cementitious compounds.

Concrete containing fly ash becomes stronger, more durable, and more

resistant to chemical attack.

Mechanically, fly ash also pays dividends for concrete production.

Because fly ash particles are small, they effectively fill voids. Because

fly ash particles are hard and round, they have a “ball bearing” effect that

allows concrete to be produced using less water of consistency leading to

lower initial porosity. Both characteristics contribute to enhanced

concrete workability and durability.

4.2.3.3 Silica Fume

Silica fume is a byproduct of producing silicon metal or ferrosilicon

alloys. One of the most beneficial uses for silica fume is in concrete.

Because of its chemical and physical properties, it is a very reactive

pozzolan, (see data sheet in Appendix A).

4.2.4 Admixtures

4.2.4.1 High Range Water Reducer (HRWR)

A highly effective water reducing agent was used as a superplasticizer,

(see data sheet in Appendix B.


114

4.2.5 Reinforcing steel bars

The main mechanical properties of used steel bars (12 mm diameter) are

presented in table (4-7).

Table (4-7) Mechanical properties of steel bars Property Test result

Yield stress (MPa) 362.85

Ultimate stress (MPa) 558.98

Elongation percent (%) 20.0

4.2.6 Materials used to prevent steel bars from corrosion

4.2.6.1 Epoxy- zinc coat

It is an epoxy one component primer, modified with zinc to provide

protection against corrosion for steel, (see data sheet in Appendix C).

4.3 Testing Procedures

4.3.1 Compressive strength test

Two hundred ninety four standard concrete cubes ( 21cube for each mix,

14mixes) with158mm side length were prepared according to the

Egyptian standard specifications (1658/1991) volume 5. These cubes

were cured in air for 24 hours and kept in fresh water for 28 days and

tested at 3, 7, 28, 65, 91, 365 and 540days to determine its compressive

strength and the results are shown in chapter ٥.

4.3.2 Accelerated corrosion test

Thirty lollipop specimens (3 for each mix, 10 mixes) consists of concrete

cylindrical specimens of 100 mm diameter and 200 mm height, in which

steel bar of 12 mm diameter and 350 mm length was centrally inserted.

Specimens were subjected to accelerated corrosion using the


115

galvanostatic method in which a current is impressed through the

reinforcing steel bar by applying a fixed potential across the anode and

an external cathode. The voltage is supplied by DC power source. An

electronic voltmeter is used to measure the current intensity in the circuit

by recording the potential difference between a fixed resistance of 100

Ohm.

The circuit current is calculated as the product of the measured potential

difference divided by the resistance.

100.0

200.

035

0.0

70.0

(A)(A)

Steel Bar, 12 mm Diam.

Section (A-A)

60.0

70.0

Diam. = 100 mm

Fig. (4-1): Schematic Figure of Lollipop Specimen

In this cell the concrete specimen is immersed in a 10 % sodium chloride

(NaCl) solution at the room temperature and connected to a constant 12

voltage DC power supply.

A steel plate is submerged in the solution. In this cell, the steel bar acts as

the anode where the steel plate acts as the cathode. The steel plate is

cleaned periodically to prevent depositing of salt on the surface.


116

In this test, the resulting current values are manually recorded every 2

hours and the cracking of the specimen is observed by visual inspection.

The total steel loss, m is determined using Equation:

m= M.I.Δt / Z.F

(4-1)

Where :

m =Mass of steel consumed (gm)

M = The atomic weight of metal (55.85g/mol for iron )

I = Electrical current (amperes)

Δt = The time interval (seconds)

Z = The ionic charge (2 for iron)

F = Faraday's constant (96485.3A.s)

Corrosion time: the Corrosion time is the time from starting the test to the

instant when the failure level is attained and the results are presented in

chapter 5.

150

mm

Power Supply

12 Volt

Lollipop Specimen

Solution

Avometer

Steel PlateCathode

+

10% NaCl

R= 100 Ohm

Fig. (4-2): Schematic figure of the Accelerated Corrosion Cell


117

Fig. (4-3): Accelerated corrosion Cell

4.3.3 Sulfate resistance

4.3.3.1 Sulfate resistance of concrete exposed to sulfate solution

Three hundred twelve concrete specimens with 100 mm length (24 for

each mix, 13 mixes) were cured in water for 28 days, and then divided

into two groups. The first group was immersed in a fresh water and the

second group was immersed in a solution of sodium sulfate ( Na2SO4) (

50 gm/L) according to ASTM C 1012 and tested at different ages 4, 8

and 12 months to determine the effect of sulfate on the compressive

strength and weight loss. The results are introduced in chapter 5.

4.3.3.2 Potential Expansion of cement mortar exposed to sulfate

Twelve concrete prisms (3 for each type of cement, 4types of cement)

having 25*25*285 mm dimensions were cured for 14 days in water then

the length was measured and the expansion was calculated by:

L2-L1Esu = (

L ) *100

Where:

Esu : is the percentage of mortar expansion due to presence of SO3

L2: is the difference between the initial length of specimen and the length

of the calibration rod (mm)


118

L1: is the difference between the length of specimen at 14 days and the

length of the calibration rod (mm)

L: is the difference between the effective length of specimen, equals 250

(mm). test results are presented in chapter 5.

4.3.4 High temperature resistance

Fifty two concrete specimens having 70 mm length (4 for each mix, 13

mixes) were cured for 28 days in water then subjected to high

temperature at 400 and 600°C for 3 hours; and tested after cooling at

ambient temperature to determine the effect of high temperature on the

compressive strength of the cubic specimens. test results are introduced

in chapter 5.

Fig. (4-4): Mould of expansion specimen

Fig.(4-6): High temperature oven

Fig. (4-5) :Expansion

specimen apparatus

119

CHAPTER 5

TEST RESULTS AND ANALYSIS

5.1 Introduction

In this chapter, the behavior of the concrete produced by local PLC

cement including strength, strength development, corrosion resistance,

sulfate resistance and resistance to different exposure conditions under

status are investigated and the variables considered are limestone content,

cement content with different cement grade, use of mineral admixture

and use of chemical admixtures.

5.2 Compressive strength and strength gaining

For comparison purpose, the cement concrete mixtures were

proportioned to have equal slump and cement content as well as the

control mixture (CEM I cement) concrete (control mixture). The control

mixture was proportioned to achieve a slump between 30–60 mm.

Detailed mix proportions are given in chapter 3. Cubes were prepared

and cured according to ECP- 203/2003. Compressive strength was

determined at different ages of 3, 7, 28, 56, 91, 365 and 540 days

respectively. C1, C2 and C3 are the control mixes, C1 with 0%

limestone is the control mix for C5, and C11. All these mixes have

cementitious content of 300kg/m3; mixes C5, C11 have limestone

contents of 15% and 25%, respectively.

C2 with 0% limestone is the control mixture for C6 and C12. All these

mixes have cementitious content of 350kg/m3; mixes C6 and C12 has

limestone contents of 15% and 25%, respectively.

C3 with 0% limestone is the control mixture for C9, C14, C7, C8, and

C13. All these mixes have cementitious content of 400kg/m3; mixes C9,

C14 have limestone contents of 15% and 25%, respectively. Mixes C7

and C8 have 15% limestone content; where C7 has a silica fume content

of 8% as replacement of the cement content and C8 has a fly ash content

Chapter 5 Test results and analysis

120

of 30% as replacement of the cement content; while C13 has 25%

limestone content with chemical admixture.

C4 with 0% limestone and has cementitious content of 450kg/m3.

C16 is a special mix with 0% limestone content and strength grade 42.5

while all other mixes made by cement with strength grade 32.5

Figure (5-1) and table (5-1) show the compressive strength of the various

concrete mixes up to curing ages of 540 days.

Fig. (5-1): Compressive strength of the various concrete mixtures up to

curing ages of 540 days.


121

Table (5-1): Compressive strength of the various concrete mixtures up

to curing ages of 540 days.

Mix

No.

Compressive strength* at different ages

(MPa)

3

days

7

Days

28

days

56

days

91

days

365

days

540

days

C1 15.16 16.33 24.57 25.09 26.00 28.09 28.62

C2 21.04 25.61 30.58 34.37 39.59 39.72 39.98

C3 22.74 25.61 34.63 38.81 44.03 44.03 44.03

C4 26.26 32.14 40.77 44.56 48.61 48.61 49.00

C5 12.94 16.66 20.25 24.17 26.13 26.85 27.18

C6 15.81 21.76 25.74 33.32 33.45 33.45 34.23

C7 21.36 29.40 41.94 42.07 46.26 51.16 53.70

C8 9.02 21.76 33.52 38.42 43.12 43.90 44.30

C9 16.86 23.52 30.58 34.89 37.11 37.50 37.50

C10 8.10 8.36 12.15 17.38 18.16 21.17 21.17

C11 10.19 13.59 22.87 29.01 30.84 31.36 31.36

C12 22.08 23.91 32.93 35.28 35.48 38.94 39.07

C13 12.50 18.00 27.30 31.15 33.33 34.00 34.00

C14 20.65 26.07 35.02 41.81 43.77 44.10 44.56 * Average of 3 cubes for each result

5.2.1 Effect of limestone content on strength and strength

gaining

To study the effect of limestone content on the compressive strength,

Figures (5-2) to (5-8) shows the compressive strength, obtained for

concrete mixtures made with cements containing limestone contents of

0, 15 and 25% by using the cement contents of 300, 350 and 400 kg/m3,

respectively.


122

Fig. (5-2): Compressive strength for concrete mixtures made of

cements containing 0, 15% and 25% limestone with cement

content (Cc) 300, 350 and 400 kg/m3, respectively, at 3days.



content (Cc) 300, 350 and 400 kg/m3, respectively, at 7days.


123

Fig. (5-4): Compressive strength for concrete mixtures made of cements

containing 0, 15% and 25% limestone with cement content

(Cc) 300, 350 and 400 kg/m3, respectively, at 28days.



content (Cc) 300, 350 and 400 kg/m3, respectively, at

56days.


124








125



content (Cc) 300, 350 and 400 kg/m3, respectively, at

540days.

Figures (5-2) to (5-8) show that the compressive strength values of the

concrete mixtures made with cement contents of 300, 350 and 400 kg/m3

decrease with increasing limestone content. This agrees with the

literature review which indicates that including large quantity of

limestone large quantities (i.e. 15% - 25%) it acts as a diluent, so that the

strengths obtained are lower than those obtained for comparable

Portland cements. The dilution effect is seen at higher dosages unless the

cement is ground to finer grain size to compensate the strength reduction

of concrete made of limestone- filled cements.


126

5.3 Accelerated corrosion test

5.3.1 Corrosion current

In the used corrosion cell the corrosion current intensity was measured at

constant time intervals every 2hours till the failure by splitting tension

crack as a result of the reinforcing bar expansion due to corrosion.

The corrosion time can be defined as the time from starting the test to the

instant when the corrosion crack was attained. Figure (5-9) and table (5-

2) show the corrosion time for reinforcing steel embedded in the concrete

specimens made of the different types of cements (CEM I,CEM II/ A,

CEM II/ B) with different cement contents (300, 350, 400 kg/m3) .

Fig. (5-9): The corrosion times for different concrete specimens.


127

Table (5-2): The corrosion time for the concrete specimens.

5.3.2 Mass Loss

The mass loss over a given time can be estimated from corrosion currents

using Faraday's law:

m=M.I.∆t/Z.F (5-1)

Where:

m=Mass of steel consumed (g)

M= Atomic weight of metal (55.85g/mol for Iron)

I= Corrosion current (Amperes)

∆t= Time interval (seconds)

Z= Ionic charge (2 for Iron)

F= Faraday's constant (96485.3 Columb)

The total mass loss mt over the given corrosion time was determined

from the area under the corrosion current versus time curve by

integration as follows:

mt = M∫I. ∆t /Z.F (5-2)

M = Atomic weight of metal (55.85g/mol for Iron)

∫I. ∆t = Electrical charge Q

Sample Corrosion Time (hours)

C1 140

C2 186

C3 120

C5 130

C6 172

C7 92

C10 41

C11 98

C12 98

C14 215


128

Z = Ionic charge (2 for Iron)

F = Faraday's constant (96485.3 Columb)

The mass losses at the end of tests for concrete specimens are given in

figure (5-20) and table (5-3).

Fig. (5-10): The mass loss for rebar in concrete specimens.

Table (5-3): The mass loss for rebar in concrete specimens.

Sample Calculated Mass loss (g) for 2 specimens

C1 9.08 5.03

C2 5.10 6.28

C3 2.55 3.04

C5 3.97 4.09

C6 9.51 7.11

C7 2.90 3.27

C10 1.70 1.46

C11 3.06 2.42

C12 3.45 3.30

C14 5.70 10.52


129

5.3.3 Crack patterns

Crack patterns show the cracks as detected by visual inspection during

the test. The crack propagation was different. Figure (5-11) represent the

typical crack pattern and corrosion products for tested specimens.

Fig. (5-11):Typical crack pattern.

1

5.3.4 Effect of limestone content on corrosion resistance

Fig. (5-12): Corrosion time and compressive strength of concrete made

of PLC vs. limestone content for mixes.


130

Figure (5-12) presents the corrosion time (average value of two

specimens) and compressive strength vs. limestone content for concrete

mixes having cement contents of 300, 350 and 400 kg/m3. The limestone

cement specimens indicate a clear decrease of the corrosion time and

compressive strength compared to the pure cement specimens; the

corrosion time and compressive strength decrease as the limestone

content increases up to 25%. It indicates that the compressive strength is

a good indicator for corrosion time and corrosion resistance.

Figure (5-13) presents the corrosion potential vs. exposure time and

limestone content for concrete mixes having compressive strength 20-25

MPa. The limestone cement specimens indicate a clear decrease of the

corrosion potential, compared to the pure cement specimens, the

corrosion potential decreases as the limestone content increases up to

15%. The corrosion potential of specimens with 25% limestone is

slightly increased.

The decrease of potential is an indirect indication that the Portland

limestone cements actually provide anti-corrosive protection. The anti-

corrosion effect is greater as the limestone content increases. As a matter

of fact, corrosion potential should be considered only as a measure of

specimen's trend for corrosion and not as an absolute measure of

corrosion itself.


131

0

100

200

300

400

500

600

700

0 20 40 60 80 100 120 140

Pot

enti

al (

mV

)

Time (Hours)

0% limestone, 32.5

15% limestone, 32.5

25% limestone, 32.5

Fig. (5-13): Corrosion potential vs. time for mixtures having

compressive strength 20-25 MPa.

Figure (5-14) presents the mass loss of rebars (average value of two

specimens) for concrete mixes having compressive strength 20-25 MPa.

It is shown that there is an explicit decrease of corrosion in specimens

made of cement with limestone. The mass loss of rebars decreases as the

limestone content increases.

The limestone is effective in protecting steel bars from corrosion. The

best predictor of corrosion resistance is compressive strength. The higher

the strength, the more resistant the concrete to corrosion, so corrosion

resistance of LPC concrete can be considered equivalent or even

superior to OPC concrete as long as compressive strengths are

comparable. It is to be noted the LPC concrete may need to use higher


132

cement content compared to OPC concrete to maintain the same

compressive strength as shown in section (5-2).

0

1

2

3

4

5

6

7

8

0 5 10 15 20 25

Mas

s lo

ss, (

g)


Fig. (5-14): Mass loss of rebars for mixes having compressive strength

20- 25 MPa


133

5.4 Sulfate resistance

5.4.1 Sulfate resistance of concrete cubes

The specimens used were cubes 10*10*10 (cm). These specimens were

immersed in a 5% Na2SO4 solution according to ASTM C-1012. Initially,

the specimens were cured at room with relative humidity of 95–98% and

temperature of 35 ± 2 oC for 24 hours, then specimens were cured in

water up to 28 days. After that, were divided into 2 groups; the first

group was continuously cured in tap water while the second group was

immersed in a 5% Na2SO4 solution , while both were tested after 4, 8, 12

months to determine the effect of sulfates on the compressive strength

and weight loss of cubes. Each result is considered as the average of 4

cubes.

The effect of sulfate solution on the performance of cement was

evaluated by measuring the reduction of compressive strength and

weight.

The reduction in compressive strength was calculated as follows:

Reduction in compressive strength, % = [(A-B)/ (A)]×100

Where: A= Average compressive strength of four specimens cured in tab

water, MPa.

B= Average compressive strength of four specimens exposed to the test

solution, MPa.

Reduction in weight, % = [(C-D)/ (C)] ×100

Where: C= Average weight of four specimens cured in tap water, kg.

D= Average weight of four specimens exposed to the test solution, kg.

Results are shown in tables (5-4) and (5-5), and figures. (5-15) and

(5-16).


134

Table (5-4): Reduction in compressive strength of concrete

specimens exposed to sulfate solution for 12 months.

Mix

No.

Reduction in Compressive Strength* after exposure

time for months (%)

4

months 8

months

12

Months

C1 0.66 3.04 1.33

C2 -7.25 9.12 5.41

C3 -21.28 -26.14 7.70

C5 -4.72 10.79 8.13

C6 9.95 -3.68 -12.09

C7 7.89 3.23 11.50

C8 6.85 -5.49 -3.87

C9 4.60 -0.41 0.70

C10 -20.33 -14.48 100.00

C11 0.00 5.71 6.91

C12 3.15 -1.78 7.06

C13 -12.70 -15.90 -40.56

C14 22.56 8.64 8.40 * Average of 4 cubes for each result


135

Table (5-5): The loss in weight of concrete specimens exposed to

sulfate solution for 12 months.

Mix

No.

The loss in weight * after exposure time for months

(%)

4

months 8

months

12

Months

C1 -0.04 -0.18 -0.59

C2 0.43 0.56 0.34

C3 0.04 0.19 0.26

C5 0.24 0.23 -0.55

C6 0.03 0.04 -0.05

C7 0.15 -0.63 -2.06

C8 0.44 2.10 0.23

C9 0.22 0.63 -0.08

C10 0.01 -0.50 100.00

C11 0.23 -0.05 -0.23

C12 0.21 0.29 0.01

C13 0.41 -0.27 0.50

C14 0.30 1.16 -0.20 * Average of 4 cubes for each result


136

Fig. (5-15): The reduction in compressive strength of concrete

specimens exposed to sulfate solution for 12 months.

Fig. (5-16): Weight loss of concrete specimens exposed to sulfate

solution for 12 months.


137

Figure (5-17) shows the deterioration in concrete specimens exposed to

5% sulfate solution for 12 months; Severe deterioration was noted in

C10.

Fig. (5-17): Concrete specimen C 10 exposed to 5% sulfate solution for

12 month.

5.4.1.1 Limestone content effect on sulfate resistance of concrete

cubes

Test results are not conclusive and that agrees with literature review that

indicates no relation was found between limestone content and sulfate

resistance of concrete.

Twelve mortar specimens (3 for each type of cement) measuring

25*25*285mm were prepared. These specimens were cured for 14 days

in water then the length was measured and the expansion is calculated

by:

L2-L1 Esu = (

L ) *100

, and the results are shown in table (5-6) and figure (5-18)

5.4.2 Sulfate resistance of cement mortar exposed to sulfate

(Potential Expansion)


138

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.000% limestone, 42.5 0% limestone,32.5 15% limestone, 32.5 25% limestone, 32.5

Limestone content( %), cement grade (MPa)

Exp

ansi

on p

erce

nta

ge (

%)

Table (5-6): Linear expansion percentage of mortar prisms

Type of Cement Expansion Percentage*

CEMI32.5 -0.248

CEMII/A32.5 -0.174

CEMII/B32.5 -0.107

CEMI42.5 -0.197 * Average of 3 cubes for each result

As shown in figure (5-18), results indicate that the linear expansion of

mortar made by PLC with limestone content 25% is lower than those

made by PLC with limestone content 15% and OPC; this result is in

agreement with literature review. In general, results as shown in figure

(5-18) indicate that limestone imparted some improvement in sulfate

5.4.2.1 Effect of Limestone content on Sulfate resistance of

cement mortar exposed to sulfate (Potential Expansion)

Fig. (5-18): Linear expansion percentage of mortar prisms for the

different types of cement


139

resistance of PLC as compared with ordinary Portland cement, and the

use of limestone improves the sulfate resistance of mortars made of PLC

to a certain extent, but such an extent is still less than that obtained for

mortars made of sulfate resisting cement (SRC).

5.5 High temperature resistance

Concrete specimens were cured for 28 days in water then exposed to fire

at different high temperatures between 400° and 600°C for three hours

to determine its effect on the compressive strength of concrete cubes and

the results are given in the tables (5-7) and (5-8) and graphically as

shown in Figs. (5-19) and (5-20).

Table (5-7): Reduction in compressive strength after thermal


and tested at 0 and 24 hours.

Compressive Strength Mix

No.

Cement

Content

(kg)

Type

of

cement

W/C

Ratio After 0

hours (%) After 24

hours (%)

C1 300 0.7 63.19 46.33

C2 350 0.6 47.62 44.58

C3 400

CEMI 32.5

0.53 59.89 53.77

C5 300 0.7 75.94 61.37

C6 350 0.6 77.05 55.00

C7 0.42 67.64 60.12

C8 0.42 87.38 91.95

C9

400

CEMI 32.5

+

CEMII/B

32.5 0.53 74.33 63.61

C10 300 0.7 74.51 44.28

C11 350 0.6 77.73 57.60

C12 0.53 52.24 77.83

C13 400

CEMII/B

32.5

0.42 87.85 57.75

C14 350 CEMI 42.5 0.6 74.55 62.93


140

Table (5-8): Reduction in compressive strength after thermal


and tested at 0 and 24 hours

Compressive Strength Mix

No.

Cement

Content

(kg)

Type

of

cement

W/C

Ratio After 0

hours (%) After 24

hours (%)

C1 300 0.7 101.75 89.43

C2 350 0.6 55.42 56.40

C3 400

CEMI 32.5

0.53 69.73 64.02

C5 300 0.7 86.09 84.48

C6 350 0.6 80.79 77.25

C7 0.42 90.26 114.09

C8 0.42 100.90 110.07

C9

400

CEMI 32.5

+

CEMII/B

32.5 0.53 72.06 70.63

C10 300 0.7 108.75 78.20

C11 350 0.6 85.96 84.24

C12 0.53 70.23 73.38

C13 400

CEMII/B

32.5

0.42 91.18 88.89

C14 350 CEMI 42.5 0.6 83.47 78.59

The results of tables (5-7)and (5-8) and figs. (5-19)and (5-20) indicate

that, in some cases, there is an appearance of an initial increase in the

strength values as a result of thermal treatment at 400° C; this result is

meanly attributed to internal autoclaving which causes an increase in the

amount of hydration products (degree of hydration) as a result of the

hydrothermal reaction (steam curing process).


141

Fig. (5-19): The reduction in compressive strength after exposure of

concrete specimens to thermal treatment at 400 and 600°C

for 3 hours and tested after 0 hours in room temperature.

Fig. (5-20): The reduction in compressive strength after exposure of

concrete specimens to thermal treatment at 400 and 600°C

for 3 hours and tested after 24 hours in room temperature.


142

To study the effect of limestone content on concrete thermal resistance,

Figures (5-41) to (5-44) show the reduction in compressive strength, for

cement mixtures with limestone contents of 0, 15 and 25% for concrete

specimens made with cement contents of 300, 350 and 400 kg/m3after

thermal treatment at 400 and 600oC for 3 hours .

The results are not conclusive and that agrees with the literature review

that indicates no relation between the limestone content and the reduction

in compressive strength of concrete.

0

20

40

60

80

100

120

0 5 10 15 20 25

Com

pres

sive

str

engt

h ,%

of

orig

inal

Limestone Content (%)

cc= 300 cc= 350

cc= 400 cc= 350, 42.5

5.5.1 Influence of limestone content on high temperature

resistance.



after 0 hours.


143

0

10

20

30

40

50

60

70

80

90

100

0 5 10 15 20 25

Com

pres

sive

str

engt

h ,%

of

orig

inal


cc= 300 cc= 350

cc= 400 cc= 350, 42.5

0

10

20

30

40

50

60

70

80

90

0 5 10 15 20 25

Com

pres

sive

str

engt

h ,%

of

orig

inal


cc= 300 cc= 350

cc= 400 cc= 350, 42.5



after 24 hours.



after 0 hours.


144

0

10

20

30

40

50

60

70

80

90

0 5 10 15 20 25

Com

pre

ssiv

e st

reng

th ,%

of

orig

inal


cc= 300 cc= 350

cc= 400 cc= 350, 42.5

As shown from the results obtained in this chapter, the compressive

strength represents the main factor in judging the durability of concrete.

To produce concrete by using PLC instead of OPC, 21 mixes were

prepared with different cement contents, types of cement and different

water/ cement ratios. To study the relation between cement and limestone

contents on the compressive strength of concrete mixes, concrete cubes

were prepared using 158mm3 cubic moulds according to (E.C.P

203/2003). Table (5-9) shows the proportions of the ingredients of

concrete mixtures and table (5-10) shows the compressive strength at 7

and 28 days. The strength values are also graphically represented versus

the water/ cement ratio in figs. (5-25) and (5-26) after 7 and 28 days of

curing, respectively.



after 24 hours.

5.6 The effect of cement and limestone contents on the

compressive strength of concrete mixes


145

Table (5-9): The details of cement mixes and the variables considered.

Mix

No. Type of cement

Cement

Content

(kg/m3)

W/ C

ratios

1 CEMI 32.5 300 0.68

2 CEMI 32.5 350 0.59

3 CEMI 32.5 450 0.47

4 CEMI 42.5 300 0.68

5 CEMI 42.5 350 0.59

6 CEMI 42.5 450 0.47

7 CEMI 52.5 300 0.68

8 CEMI 52.5 350 0.59

9 CEMI 52.5 450 0.47

10 (CEMI 32.5+CEMII/B 32.5) 300 0.68

11 (CEMI 32.5+CEMII/B 32.5) 350 0.59

12 (CEMI 32.5+CEMII/B 32.5) 450 0.47

13 (CEMI 42.5+CEMII/B 32.5) 300 0.68

14 (CEMI 42.5+CEMII/B 32.5) 350 0.59

15 (CEMI 42.5+CEMII/B 32.5) 450 0.47

16 (CEMI 52.5+CEMII/B 32.5) 300 0.68

17 (CEMI 52.5+CEMII/B 32.5) 350 0.59

18 (CEMI 52.5+CEMII/B 32.5) 450 0.47

19 CEMI/B 32.5 300 0.68

20 CEMI /B32.5 350 0.59

21 CEMI/B 32.5 450 0.47


146

Table (5-10): The compressive strength at 7 and 28 days.

Compressive strength Mix No.

At 7 days

(MPa)

At 28 days

(MPa)

1 17.9 19.3

2 18.4 22

3 22.2 29.1

4 16.2 20.5

5 22 26.6

6 29.6 30.7

7 17.7 24

8 19.7 27.1

9 25.1 35.4

10 12.3 18.9

11 15.4 20.6

12 20.8 23.9

13 12 17.3

14 14.5 20.5

15 20.5 26.3

16 15.2 18.1

17 16.1 22.5

18 23.2 24.8

19 12.3 17.7

20 14.4 19.3

21 18.9 22.4


147

0

0.45 0.5 0.55 0.6 0.65 0.7

Com

pres

sive

str

engt

h at

7 da

ys (

MP

a)

water cement ratio

CEM I 32.5 CEM I 42.5

CEM I 52.5 CEM I 32.5 + CEM II 32.5

CEM I 42.5 + CEM II 32.5 CEM I 52.5 + CEM II 32.5

CEM II 32.5 B.S

Fig. (5-25): The relation between compressive strength of concrete and

water: cement ratio for the concrete specimens made from

different types after 7days of curing.


148

0

0.45 0.5 0.55 0.6 0.65 0.7

Com

pres

sive

str

engt

h at

28

days

(M

Pa)

water cement ratio

CEM I 32.5 CEM I 42.5

CEM I 52.5 CEM I 32.5 + CEM II 32.5


CEM II 32.5 B.S


water: cement ratio for the concrete specimens made from

different types after 28 days of curing.


149

0

5

10

15

20

25

30

35

40

250 300 350 400 450

Com

pres

sive

str

engt

h at

7 da

ys (

MP

a)

Cement content( kg/m3)

CEM I 32.5 CEM I 42.5

CEM I 52.5 CEM I 32.5 + CEM II 32.5


CEM II 32.5 B.S


cement content for the concrete specimens made from

different types after 7days of curing.


150

0

5

10

15

20

25

30

35

40

250 300 350 400 450

Com

pres

sive

str

engt

h at

28

days

(M

Pa)

Cement content( kg/m3)

CEM I 32.5 CEM I 42.5

CEM I 52.5 CEM I 32.5 + CEM II 32.5


CEM II 32.5 B.S

Fig. (5-28): Fig.(5-25): The relation between compressive strength of

concrete and cement content for the concrete specimens

made from different types after 28 days of curing.


151

Figures (5-25) and (5-26) show the relation between compressive

strength and water/ cement ratio for the concrete specimens made of the

different seven types of cement after 7 and 28 days of curing and Figures

(5-27), (5-28) show the relation between compressive strength of

concrete specimens and cement content for different seven types of

cement at the curing ages of 7 and 28 days, to fulfill the target of

compressive strength using different types of cements.

152

CHAPTER 6

SUMMARY AND CONCLUSIONS

6.1 Summary

The main objective of this investigation is to explore the long-term

performance and fire resistance of the concrete produced by Portland

limestone cement (PLC). The mean variables considered in the current

study include influence of PLC cement compared to ordinary Portland

cement (OPC), cement content, effect of mineral and chemical

admixtures.

To achieve the research objectives, experimental and analytical studies

were carried out and documented in this thesis.

Fourteen concrete mixes were made with different cement and limestone

contents, the concrete characteristics considered include:

Compressive strength for concrete cubes, at 7 different ages

(namely 3, 7, 28, 56, 91, 365and 720 days

The corrosion protection resistance for reinforced concrete

specimens; "Lollipop" specimens were cast and tested in

accelerated corrosion environment. Specimen's response is

presented in terms of corrosion current, corrosion time, mass loss

and crack patterns.

The sulfate resistance of concrete and mortar specimens ; Cubic

specimens were cast and tested to determine the strength

reduction and weight loss after submerging in sulfate solution.

Also, the expansion of mortar prisms was measured.

Chapter 6 Summary and conclusions

153

The high temperature resistance was evaluated using concrete

cubes where the strength reduction was determined after

subjecting the concrete to 400 and 600oC for 3 hours. The

concrete strength was determined directly after subjecting to the

heat and after cooling in room temperature for 24 hours.

6.2 Conclusions

The main conclusions derived from this investigation can be summarized

as follows: for the same cement content and water/cement ratio the

compressive strength for PLC concrete is less than that of OPC concrete

and the reduction in compressive strength is proportional to the

limestone content. However, to attain comparable compressive strength

with OPC concrete, PLC concrete should contain higher cement content

and lower water/cement ratio. It is concluded that if the compressive

strengths of both PLC and OPC concretes are comparable, PLC concrete

is as good as OPC in both short and long term characteristics. On the

other hand, compared to OPC concrete, PLC concrete has lower drying

shrinkage and comparable high temperature resistance. Therefore, it is

concluded that PLC can be used in producing plain and reinforced

concrete provided that the cement content and water/ cement ratio are

modified to achieve the specified compressive strength.


154

6.2.1 Conclusions regarding compressive strength

From the analysis and discussion of the test results obtained in the

current research, it is concluded that for the same cement content and

water/cement ratio the compressive strength values obtained for PLC

concrete are less than that of OPC concrete and the reduction in

compressive strength is proportional to the limestone content; the

reduction in compressive strength of the concrete specimens made with

cement different contents (300, 350, 400kg/m3) increases with increasing

the limestone content of PLC.

Tables (6-1), Figure (6-1) show the reduction in compressive strength in

PLC concrete made with 15% and 25% limestone contents as compared

to OPC concrete.

Table (6-1): Reduction in compressive strength for PLC concrete as

percentage of OPC concrete (cement content 300, 350, 400

kg/m3)

Type of cement Reduction in compressive strength as % of OPC

concrete for different cement contents

Cement content 300 kg/m3 350 kg/m3 400 kg/m3

PLC, with 15%

limestone

17.58 15.83 11.70

PLC, with 25%

limestone

50.55 25.21 21.17


155

0

5

10

15

20

25

30

35

40

45

50

55

300 350 400

Red

ucti

on in

com

pres

sive

str

engt

h as

% o

f O

PC

con

cret

e

Cement content, kg/m3

PLC with 15% limestone

PLC with 25% limestone

Fig. (6-1): Reduction in compressive strength for PLC concrete as

percentage of OPC concrete (cement content 300, 350, 400

kg/m3)

6.2.2 Conclusions regarding corrosion resistance

the results of corrosion resistance test indicated that the limestone is

effective in protecting the reinforcing steel embedded in PLC concrete

from corrosion. The best predictor of corrosion resistance is the value of

compressive strength: The higher the strength, the more resistant the

concrete to corrosion; so corrosion resistance of LPC concrete can be

considered equivalent or even superior to OPC concrete as long as


156

compressive strength values are comparable. Actually LPC concrete may

need to use a higher cement content as compared to OPC concrete to

maintain the same compressive strength of the concrete specimens.

Evidently for the concrete specimens made with different cement

contents (300, 350, 400kg/m3) the corrosion resistance increases with

increasing the limestone content in PLC.

Tables (6-2) shows the improvement in corrosion resistance in PLC

made with 15% and 25% limestone as compared to OPC concrete with

the same compressive strength.

Table (6-2): The mass loss for mixtures with strength 25MPa

Type of cement mass loss

OPC 7.06

PLC, with 15%

limestone

4.03

PLC, with 25%

limestone

2.74

Limestone cement specimens indicate a clear decrease of the mass loss

and corrosion potential, compared to the pure cement specimens. The

potential decrease is an indirect indication that Portland limestone

cements actually provide anti-corrosive protection. The anti-corrosion

effect is greater as the limestone content increases.


157

No relation was found between limestone content and sulfate resistance

of concrete. The linear expansion of mortar made with PLC with

limestone content 25% is lower than that made with PLC with limestone

content 15% and OPC; this indicates that the limestone imparted some

improvement in sulfate resistance of PLC as compared to OPC, and the

use of limestone improves the sulfate resistance of mortars, but with a

less extent than that made of sulfate resisting cement (SRC).

6.2.4 Conclusions regarding heat resistance

Heat resistance tests show mixed results, in some cases being increased

and in other cases decreased in limestone Portland cements when

compared to control (OPC) cements.

6.3 Recommendations

In the light of the results of the present study, Portland limestone cement

is recommended in construction concrete producing with satisfying

resistance to corrosion and sulfate attack, high temperature resistance

and compressive strength by reducing the water/cement ratios.

6.2.3

Conclusions regarding sulfate resistance for concrete

cubes and linear expansion of mortars

158

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Appendix A

173

Data sheet of silica fume

Appendix A

174

Appendix A

175

Appendix B

176

Data sheet of high range water reducer

Appendix B

177

Appendix C

178

Data sheet of Epoxy- zinc coat

Appendix C

179

٢٠١١ –القاهرة

كلية الهندســة

قسم الهندسة االنشائية

األدائية بعيدة المدى للخرسانة المصنعة من أسمنت بورتالندي الحجر الجيري

مقدمة من

جيهان محمود علي السمني ١٩٩٨بكالوريوس الهندسة المدنية

جامعة عين شمس-كلية الهندسة

رسالـة ـة عين شمس جامع- مقدمـة إلى كلية الهندسـة

كجزء من متطلبات الحصول على الماجستيردرجة

)إنشـاءات(فى الهندسة المدنية

تحت إشراف

أحمد فتحي عبد العزيز. د.ا الهندسة االنشائية قسم - مساعدأستاذ


صالح عبد الغني أبو العينين. د.ا اءالكيمياء الفيزيائية و مواد البنأستاذ

جامعة عين شمس- علومكلية ال

هاني محمد الشافعي. د الهندسة االنشائيةقسم - مساعد أستاذ


قـــرارإ

هذة الرسالة مقدمة الى جامعة عين شمس للحصول على درجة الماجستير

ةمعرفة الباحث بهن العمل الذى تحتوية الرسالة تم اجراؤأفى الهندسة المدنية كما

.فى قسم الهندسة المدنية بجامعة عين شمس

ى أى درجة علمية فى أى جزء من هذة الرسالة لنيل أهذا ولم يتم تقديم

.خرآو معهد علمى أجامعة

وهذا اقرار منى بذك

جيھان محمود علي السمني : االسم

جيھان السمني : التوقيع

٢٠١١ / / : التاريخ

مقدم الرسالة فحة تعريفص

جيهان محمود علي السمني : ــــــمـــــــــــاالســـــــــ

١٩٧٤ / ١٢ / ٥ :ــالدتاريــــخ الميـــ

مصر-القاهرة : محــــل الميــــــالد

بكالوريوس الهندسة المدنية : ـىـــــــة األولــــــــة الجامعيــــــالدرج

جامعة عين شمس– كلية الهندسة : امعيةالجهة المانحة للدرجة الج

١٩٩٨ - مايو : نـحتاريـــــــــــخ الم

نشائية الهندسة اإلدبلوم الدراسات العليا في :الثانيـــــــــةـة ــــــة الجامعيــــــالدرج

جامعة عين شمس– كلية الهندسة : الجهة المانحة للدرجة الجامعية

٢٠٠٥ - وليوي : نـحتاريـــــــــــخ الم

جيد جدا: التقدير

كلية الهندســة قسم الهندسة االنشائية

جيهان محمود علي السمني / ملخص رسالة الماجستير المقدمة من المهندسة "األدائية بعيدة المدى للخرسانة المصنعة من أسمنت بورتالندي الحجر الجيري "

ح عبد الغني أبو العينين صال/ د.أ: أسماء السادة المشرفين أحمد فتحي عبد العزيز / د هاني محمد الشافعي/ د

الملخص

لألنواع املختلفة من األمسنت -١/٢٠٠٥-٤٧٥٦رقم -صدرت املواصفة القياسية املصرية . ١/٢٠٠٤- ١٩٧األمسنتات شائعة االستخدام رقم فنيا مع املواصفة األوربية ألنواع لتتماشى

شار إليه بالرمز ي(تلفة ومنها األمسنت البورتالندى املخلوط خمأمسنت على أنواع وحتتوى هذه املواصفةCEM II ( ٦٥والذى يتكون بصفة اساسية من األمسنت البورتالندى العادى بنسبة ترتاوح بني -

ويعترب امسنت البورتالندي %. ٣٥-٦ئة بنسب متغرية من مع اضافات بوزوالنية أو مواد مال % ٩٤احلجر اجلريي املضاف اليه اضافة مالئة من مطحون احلجر اجلريي عايل النعومة أحد أكثر هذه األنواع

.شيوعا من األمسنت املخلوط

تؤثر إضافة بودرة احلجر اجلريى مع األمسنت البورتالندى العادى تأثريا إجيابيا على ختفيض كمية واحلصول على أمسنت أفضل مع الطاقة املطلوبة ىف صناعة األمسنت، وبالتبعية ختفيض تكلفة االنتاج

ة األمسنت ولكن وال تعترب اضافة بودرة احلجر اجلريى كمادة مالئة ذات فائدة لتحسني مقاوم. بيئياقابلية : بالنظر إىل خواصها الطبيعية يكون هلا بعض املزايا لتحسني خواص اخلرسانة الناجتة مثل

ومن جهة اخري، يتبني ان خرسانة أمسنت . ، التشرخ )النضح(، النزيف )املسامية(النفاذية التشغيل، ة خبرسانة األمسنت البورتالندى بورتالندى احلجر اجلريى ذات مقاومة أقل على املدى القصري مقارن

مر الذي يتضح منه وجود حاجة ملحة لبحث أدائية خرسانة أمسنت بورتالندى احلجر ألا، العادىاجلريى على املدى البعيد عند تعرضها لظروف التعرض املختلفة لدراسة تطور املقاومة والتحمل مع

. الزمن مقارنة خبرسانة األمسنت البورتالندى العادى

ؤدي أنتاج أنواع متعددة من أمسنت بورتالندى احلجر اجلريى حمليا والذي ستعتمد خواصه على وسيطبقات ومكان التحجري تكوين الطريقة التصنيع واختالف الرتكيب الكيميائى خلام احلجر اجلريى تبعا ل

قبل استخدام ، مما يستلزم ضرورة تقييم األدائية على املدى البعيد األمسنت الناتجايل اختالف خواص .هذا املنتج اجلديد بالسوق احمللى ىف أعمال اخلرسانة

خلرسانة درجات احلرارة العاليةلذلك مت اجراء هذا البحث بغرض دراسة األدائية بعيدة املدى ومقاومة مصدر األمسنت، : الدراسة اهم املتغريات الرئيسية مثلمشلت أمسنت بورتالندى احلجر اجلريى حيث

تقييم اخلواص املميزة بعيدة املدي للخرسانة مترتبة اخلرسانة، ظروف التعرض املختلفة، كما املقاومة، مهامجة الكربيتات وصدأ أسياخ التسليح ومقاومة مبتابعة تطور املقاومة حتت ظروف التعرض املختلفة

.ارة العاليةاحلردرجات االنكماش ومقاومة التغريات البعديةبو

لنتائج االختبارات ،يتضح أن اخلرسانة املصنعة باستخدام أمسنت بورتالندي من التحليل واملناقشة احلجر اجلريي حتقق مقاومة ضغط أقل من اخلرسانة املصنعة من األمسنت البورتالندي العادي لنفس حمتوى األمسنت ونسبة املاء لألمسنت، وحتقق خرسانة أمسنت بورتالندي احلجر اجلريي خواص مماثلة

. ألمسنت البورتالندي العادي يف املدى القصري والبعيد املكافئة هلا يف مقاومة الضغطخلرسانة اويشمل هذا ضمنيا احلاجة اىل زيادة حمتوى األمسنت وتقليل احملتوى املائي خلرسانة أمسنت ابورتالندي

ظ أن احلجر اجلريي لتحقيق خواص مماثلة خلرسانة األمسنت البورتالندي العادي، ومن املالحاستخدام أمسنت بورتالندي احلجر اجلريي يقلل االنكماش باجلفاف واليؤثر على مقاومة درجات احلرارة العالية مقارنة خبرسانة األمسنت البورتالندى العادى، وعليه فإنه ميكن استخدام أمسنت

ى األمسنت ونسبة بورتالندي احلجر اجلريي ىف إنتاج اخلرسانة العادية واملسلحة مع مراعاة تعديل حمتو .املاء لألمسنت لتحقيق مقاومة الضغط املطلوبة