a study on behavior and improvement of expansion of

A STUDY ON BEHAVIOR AND IMPROVEMENT OF

EXPANSION OF CONCRETE WITH EXPANSIVE

ADDITIVE AND DESIGN METHOD

BY

PAKORN SUTTHIWAREE

A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE

REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE (ENGINEERING)

SIRINDHORN INTERNATIONAL INSTITUTE OF TECHNOLOGY

THAMMASAT UNIVERSITY

ACADEMIC YEAR 2014

ii

Acknowledgements

I would like to express my appreciation to my advisor, Dr. Chalermchai

Wanichlamlert, for his valuable time and suggestion. This thesis would not have been

complete without his valuable support.

I would like to express my gratitude to Professor Somnuk Tangtermsirikul

for his valuable suggestions throughout the period of my thesis work. This thesis

would not have been accomplished without his valuable advice and encouragement.

I would like to express my appreciation to thesis committee, Asst. Prof.

Dr. Pisanu Toochinda and Dr.Pitisan Krammart, for they valuable time, suggestion as

my thesis committee. This thesis would not have been accomplished without they

valuable advice.

My best appreciation and gratitude goes to my co-advisor, Dr.Raktipong

Sahamitmongkol, for his support, encouragement, and important lesson, without

which this thesis would not have been accomplished.

I also like to express my sincere thanks to ITSC Lab technicians,

Mr.Prasert Khamdee, Mr.Chanarong Phannphet, Mr,Buncherd Chotiviriyakul,

Mr.Rujipass Phanprasit, Mr.Prapass Deneng and Mr.Sumet Teienjang for assisting in

sensitive and time-consuming experiments performed as a part of this study. Sincere

thank is also given to Mr.Jiranuwat Bunjongrat for his kind support throughout my

study period at SIIT.

Finally, I would like to express my deepest gratitude to my family for all

their love, support and encouragement throughout my life to this point. I especially

want to thank my wife for her encouragement and patience that has been stimulating

me to complete this thesis and achieve other successes.

iii

Abstract

A STUDY ON BEHAVIOR AND IMPROVEMENT OF

EXPANSION OF CONCRETE WITH EXPANSIVE

ADDITIVE AND DESIGN METHOD

BY

PAKORN SUTTHIWAREE

B.Eng. Civil Engineering, King’s Mongkut Institute of Technology North Bangkok,

2004

In this thesis expansion of concrete with expansive additives were studies.

Bottom ash was used as an internal curing agent by a partial replacement in fine

aggregate.

Rrelationship between restrained expansion and dosages of expansive

additives as well as relationship between restrained expansion and restraint ratio were

studied. Four different types of expansive additives were tested to compare their

efficiencies. Compatibility between the expansive additives and fly ash is also

evaluated. The results show that, for all types of expansive additives, the restrained

expansion increases linearly with the dosages of expansive additive while reduces in

non-linear pattern with the increased restraint ratio. It was also found that the fly ash

replacement (up to 30% of total binder content) increases the restrained expansion of

concrete. Based on the findings, the new design approach is proposed as procedures to

estimate an necessary dosage of expansive additive for inducing a required restrained

expansion

This thesis also presents an experimental study on early age length change

of expansive concrete produced by adding expansive additive into concrete and

partially replacing fine aggregate with bottom ash in order to investigate the effect of

internal curing to the expansion behavior of expansive concrete. To evaluate the

length change of the expansive concrete, three experiments were conducted. Free

iv

expansion and restrained expansion were tested to confirm the behavior of early age

expansion of the expansive concrete. After that, free shrinkage was tested to study

subsequent shrinkage after the concrete was exposed to a drying environment. It was

found, from the experimental results, that bottom ash can increase expansion of

expansive concrete with and without fly ash in both free condition and restrained

condition. However, the subsequent shrinkage of expansive concrete is also increased.

The experimental finding indicates that the internal curing can potentially be applied

to increase efficiency of expansive concrete however the balance between the

enhanced expansion and the subsequent drying shrinkage must be carefully

considered.

Keyword: Expansive concrete, Restraint, Expansion, Restrained expansion,

Shrinkage, Drying shrinkage, Free shrinkage, Internal curing, Expansive additive,

Expansion efficiency

v

Table of Content

Chapter Title Page

Signature Page i

Acknowledgements ii

Abstract iii

Table of Contents v

List of Figures vii

List of Tables ix

1 Introduction 1

1.1 General 1

1.1.1 Cracking of Concrete 1

1.1.2 Mechanism of Shrinkage Cracking 3

1.1.3 Expansive Concrete 4

1.2 Statement of Problem 8

1.3 Objective 8

1.4 Scope of Study 8

2 Literature Review 9

2.1 Expansive Cement and Expansive Additive 9

2.2 Basic Properties of Expansive Concrete 10

2.3 Prediction Model of Cracking Age of Concrete 13

2.4 Prediction Model of Net Expansion 14

2.5 Design and Test Method 16

2.6 Internal Curing 20

vi

3 Research Methodology 22

3.1 General 22

3.2 Material 22

3.3 Mix Proportion 25

3.4 Method of Testing 26

4 Result and Discussions 32

4.1 Effect of Type and Amount of Expansive Additive 32

4.2 Expansion Efficiency 37

4.3 Effect of Restraint Ratio on Restrained Expansion 38

4.4 Effect of Internal Curing 43

5 Proposed Design Approach 51

5.1 General Procedure 51

5.2 Required Member Expansion 51

5.3 Necessary Restrained Prism Expansion 51

5.4 Determination of Expansive Additive 53

6 Conclusion and Recommendations 54

6.1 General 54

6.2 Recommendation for Further Study 54

References 55

Appendix 58

vii

List of Figures

Figures Page

1.1 Restrained tensile crack on the large floor 1

1.2 Restrained tensile crack on the roof-deck 2

1.3 High restraint structure (Swimming pool) 2

1.4 Restrained tensile crack under swimming pool 2

1.5 Illustration of shrinkage cracking mechanism of concrete 4

1.6 Conceptual illustration of crack control mechanism of

expansive concrete 5

1.7 Cost comparison for concrete materials in Thailand 6

1.8 Illustration of cracking age analysis 7

2.1 SEM observation on expansive mortar at 50oC 12

2.2 Chemical pre-stress and chemical pre-strain of expansive concrete 12

2.3 Geometry and size of specimen according ASTM C878 16

2.4 Mold preparing casting specimen according ASTM C878 17

2.5 Measuring restrained expansion by length comparator 17

2.6 Restraining device for JIS A6202 17

2.7 Length measuring instrument for JIS A6202 18

2.8 Length measuring instrument for JIS A6202 18

2.9 Estimation of member expansion for ettringite-based system 19

2.10 Estimation of member expansion calcium hydroxide based system 19

2.11 Internally cured bridge deck being placed in 2013 21

3.1 Experimental program 22

3.2 Fine aggregate gradation 23

3.3 Concrete setting time test apparatus 26

3.4 compressive test machine 27

3.5 Measurement of free expansion/free shrinkage 28

3.6 Geometry and size of specimens for measurement of internally

restrained expansion 29

viii

3.7 Installation of strain gages on restraining rebar and preparation of

formworks before casting 30

3.8 Moist curing by wet clothes and plastic sheets until the age of 7 days 30

4.1 Example of development of restrained expansion 33

4.2 restrained expansion of specimen with 1.571% restraint 36

4.3 Expansion efficiency of each expansive additive 37

(Restraint ratio =1.31%, w/b=0.5)

4.4 Restrained expansion of SEA with 20% FA

under different restraint ratios 38

4.5 Expansion efficiency of SEA with FA20% on different restraint ratios 39

4.6 Effect of restraint ratio on the restrained expansion at 7 day 41

4.7 Relative restrained expansion 43

4.8 Effect of BA on free expansion of normal expansive concrete 44

4.9 Effect of BA on free expansion of fly ash expansive concrete 44

4.10 Summary results of 7-day free expansion of expansive concrete

with FA and BA 45

4.11 Effect of BA on restrained expansion of normal expansive concrete 46

4.12 Effect of BA on restrained expansion of fly ash expansive concrete 46

4.13 Summary results of 7-day restrained expansion of expansive concrete

with FA and BA 47

4.14 Total shrinkage of expansive concrete with BA 48

4.15 Total length change of expansive concrete with BA 49

5.1 Relationship between relative expansion and restraint ratio 52

5.2 Relationship between member expansion and prism expansion

based on experimental in this study 53

ix

List of Tables

Tables Page

3.1 Chemical composition of powder materials. 23

3.2 Mix proportion 25

A1 Setting time tested results 58

A2 Compressive strength tested results 59

A3 Internal restrained expansion, restraint ratio 0.79% 60





A8 Free expansion 64

A9 Gradation of fine aggregate 65

1

Chapter 1

Introduction

1.1 General

1.1.1 Cracking of Concrete

Nowadays, ready-mixed concrete companies usually supply normal concrete

for construction industry. After concrete becomes hardened and obtains the required

compressive strength, some cracks may, in many cases, appear on concrete surface

during its service life (Figure 1.1 to Figure 1.5). The cracks shown in these figures

usually occur before full service loads are applied to the structures and the direction of

crack is not in the same direction as the maximum load induced tensile strain. They

were thus not caused by loading.

Most cracks of this type take place in relatively thin structures, for instance,

floor or wall, and usually become visible around several weeks to several months after

the casting of the structures. This type of cracks is the restrained shrinkage crack. If

any structure is damaged by this type of crack, the integrity or serviceability of the

structures can be drastically degraded. An intensive inspection, structural evaluation,

as well as an careful repair work is necessary to rehabilitate the structure. And, this

results in huge unexpected financial spending as well as the delay of construction.

Figure1.1 Restrained tensile crack on the large floor

2

Figure1.2 Restrained tensile crack on a roof-deck.

Figure1.3 High restraint structure (swimming pool)

Figure1.4 Restrained tensile crack under swimming pool

3

1.1.2 Mechanism of Shrinkage Cracking

Shrinkage is an intrinsic property of concrete. Although, when we cast the

concrete into formwork the concrete have dimension and size equal to the formwork.

Its volume will reduce by several reasons such as its reaction, microstructure

formation, as well as the interaction with environment. This volume reduction begins

since the concrete is in its fresh state. However, the volume change in the liquid state

cannot generate any stress and is not problematic.

Theoretically, the volume change will induce stress in concrete only after the

concrete gains some stiffness. Usually the setting time is referred as the reference

point. After the setting, the concrete may loss its volume by several reasons. This

volume reduction is mainly caused by shrinkage of concrete. There are several types

of shrinkages but two main types are “autogenous shrinkage” and “drying shrinkage”.

The autogenous shrinkage is caused by a chemical shrinkage and the corresponding

self-desiccation. While the drying shrinkage, is caused by the loss of internal moisture

to the environment.

The shrinkage of concrete is, most of the times, not allowed to occurs freely

but restrained at least by either internal or external restraints. These restraint act to

resist the shrinkage of concrete and thus the tensile stress develops in concrete. When

elastic tensile strain becomes higher than the tensile-strain capacity of the concrete,

the crack occurs. Figure 1.6 shows the schematic demonstration of the shrinkage

crack analysis of concrete structures.

4

Figure1.5 Illustration of shrinkage cracking mechanism of concrete

1.1.3 Expansive Concrete

Expansive concrete can be used to prevent the shrinkage crack by generating

expansion during early ages to compensate for the shrinkage and produce

compressive stress in restrained structures to compensate tensile stress from

shrinkage. It is important to note here that expansive concrete also have shrinkage.

Figure 1.7 shows the schematic demonstration of the crack analysis when the

expansive concrete is applied. Its difference from Figure 1.6 is clear. In the case

where expansive concrete is applied, there is a substantial expansion at very young

age. The total expansion is then reduced by the shrinkage. If sufficient expansion

occurs beforehand, the Shrinkage cracking can then be prevented.

5

Figure1.6 Conceptual illustration of crack control mechanism of expansive concrete

Expansive additive in Thailand is quite expensive when compared with other

concrete ingredients. Figure 1.8(a) shows the comparison of unit cost of each

ingredient of concrete while Figure 1.8(b) shows estimation of the cost component of

the expansive concrete marketed in Thailand. In order to practically employ the

expansive concrete in the real construction, the involved parties usually require the

performance verification. The evaluation may be in the form of cost/performance

ratios. However, so far, there is no information to verify the performance of a given

expansive additive, to compare several products, and to efficiently design expansive

concrete for a specific construction.

Expansion performances may be easily evaluated by measuring expansion

under same condition such as free expansion, restraint expansion or expansion energy.

However, the expansion is not the final outcomes expected by the engineers since the

real expectation is the prevention of crack.

6

Figure1.7(a)Unit cost of concrete raw materials

Figure 1.7(b) Proportion of cost per cubic meter of concrete

Figure1.7 Cost comparison for concrete materials in Thailand

Regarding to the prevention of crack, Dung(2010) proposed an criterion that

can be used to evaluate the occurrence of cracking at any time and the cracking age

can be predicted at the time that elastic tensile strain exceeds the cracking strain

(Figure1.9) as shown in Equation 1.1:

ε c,e (t) > ε cr,direct (t) (1.1)

0

5

10

15

20

25

30

35

Cement Fly Ash Sand Rock Chemical

Admixture

Expansive

Additive

TH

B

Unit Cost(THB/kg.)

Cost per Cubic meter of concrete

Fly Ash

3%

Sand

13%Rock

21%

Chemical

Admixture

2%

Expansive

Additive

33%

Cement

28%

7

Where:

ε c,e (t) : elastic tensile strain(µƐ)

ε cr,direct (t) : direct tensile cracking strain by time(µƐ)

t : age of concrete(day)

and

ε c,e (t) = (ρn(t)/(1+ρn(t))[ ε shr,free(t) – (1+ ρn(t)) ε exp,net(t) - ε tensile, creep(t)]

(1.2)

Where:

ε shr,free(t): free shrinkage strain by time (µƐ)

ε exp,net(t): expansion strain by time(µƐ)

ε tensile,creep(t) : tensile creep strain(µƐ)

ρ : cross section ratio = As/Ac

n : modular ratio = Es/Ec(t)

As: cross sectional area of restraining steel(mm2)

Ac: cross sectional area of concrete(mm2)

Es: elastic modulus of restrained steel (Mpa)

Ec(t): elastic modulus of concrete by time (Mpa)

Figure1.8 Illustration of cracking age analysis

8

The author consider that the criteria and cracking age proposed by Dung et al

(2010) is suitable but the method needs the accurate input of the expansion if the

expansive concrete is required. A test method and the combined use of expansive

concrete with other techniques are also usually questioned.

1.2 Statement of Problems

Expansive additive in Thailand is relatively an expensive material in

comparison to other concrete ingredients. Hence, performance analysis of

expansive additives from different sources is necessary.

Method to design and testing of restrained expansion of expansive concrete is

not currently available for Thailand.

There is still no information about a combination between expansive concrete

and other techniques that can reduce shrinkage of concrete such as internal

curing.

1.3 Objectives

Based on the above introduction and statements of problem, this research focuses on

the following issues:

To compare performance of expansive additives those have different chemical

composition.

To study effect of bottom ash on expansion and shrinkage of expansive

concrete

To proposed a design method for restraint expansion for expansive concrete

1.4 Scope of the Study

With the above objective, the scope of this study includes the following topics ;

Performance of five types of expansive additive.

Effect of internal curing by used bottom ash on expansion and shrinkage of

expansive concrete.

A method to estimate restrained expansion for concrete with expansive additive.

9

Chapter 2

Literature Review

2.1 Expansive Cement and Expansive Additive

ACI 223R-10(2010) defines expansive concrete as the concrete which is

produced with expansive cement or expansive additive. Expansive cement is cement

that can increase volume after setting for compensating shrinkage. Expansive additive

is an additive that can be added as a partial cement replacement to generate expansion

after setting for compensating shrinkage.

Expansive cement can be classified into 3 types as follow;

1. Expansive cement Type K is a mixture of Portland cement, anhydrous

tetracalcium trialuminate sulfate, calcium sulfate, and lime.

2. Expansive cement Type M is a blended mixture of Portland cement,

calcium-aluminate cement, and calcium sulfate.

3. Expansive cement Type S is a Portland cement which high tricalcium

aluminate content and an amount of calcium sulfate above the usual amount found in

Portland cement.

Expansive additive can be categorized into 4 types such as;

1. Expansive additive Type K is a blend of calciumsulfoaluminate and calcium

sulfate.

2. Expansive additive Type M is a blend of calciumaluminate cement and

calcium sulfate.

3. Expansive additive Type S is a blend of tricalciumaluminate cement and

calcium sulfate.

4. Expansive additive Type G is a blend of calciumdioxide and aluminum

dioxide.

Nagataki et al. (1998) explained expansion mechanism of expansive concrete

as follows;

1. Volume increase by water absorption of expansive component during gel

state (swelling theory)

10

2. Crystal growth of crystalline material (crystal growth theory)

3. Coexisting pore by fragmentation of expansive additive during hydration.

2.2 Basic Properties of Expansive Concrete

Nagataki et al. (1998) explained that the expansion of the expansive concrete

became larger with the increase of expansive additive content. When the expansive

additive content did not exceed 30 kg/m3 of concrete, tensile strength, bending

strength, bond strength, Young’s Modulus and creep of the expansive concrete were

about the same as those of the normal concrete. Durability of the expansive concrete

cured for a long time in water did not have uncontrollable expansion after reaching a

settled value. Sulfate resistance and wear resistance of the expansive concrete were

the same as the normal concrete.

Lam (2010) presented a study on free expansion and compressive strength of

concrete with an expansive additive. The results show that, the expansive additive is

more effective to increase free expansion of fly ash concrete than cement-only

concrete. Free expansion of expansive concrete develops in 3 days. After this period

the free expansion of concrete is constant or reduces slightly due to autogenous

shrinkage. When free expansion strain exceeds 800 micron, the compressive strength

of expansive concrete drops more than 20% of the non-expansive additive concrete.

In the research, the effect of expansive additive content, fly ash content, and water to

binder ratio (w/b) on durability such as carbonation resistance of concrete, sulfate

resistance of mortar, chloride penetration, and chloride binding capacity of paste were

studied. The results indicate that, when the expansive additive content is controlled at

below 30 kg/m3, carbonation resistance of both cement-only expansive concrete and

fly ash expansive concrete is better than that of concrete without expansive additive.

However, when amount of the expansive additive is higher than 30 kg/m3,

carbonation resistance of fly ash expansive concrete decreases. Expansive additive

has a negative effect on sulfate resistance and chloride binding capacity of concrete

but tends to reduce chloride permeability.

11

Wee et al. (2000) studied the direct tension test method and the mechanical

properties of concrete in compression, flexure and tension. The investigation shows

that the limiting strain in the uniaxial compressive test lies between 300 με and 500

με. The tensile strain capacity of concrete is between 150 με and 210 με in the flexural

strength test and is between 100 με and 140 με in direct tension test. The tensile strain

capacity obtained from flexure test has a higher standard deviation. The tensile

strength obtained from the direct tension test is about two-thirds of the flexural

strength of the concrete. The flexural strength is about 8-11.5% of the cylinder

compressive strength. The tensile strength is 5.5-8.5% of the cylinder compressive

strength.

Yan (2000) studied an effect of expansive additive and possibility of DEF

(Delay Ettringite Formation). He concluded that the expansive additive used in

massive concrete cannot provide full efficiency to its shrinkage-compensating effect,

because of the decomposition of ettringite under high curing temperature (> 70°C).

Unsafe delayed expansion would occur due to DEF at later age of shrinkage-

compensating massive concrete. It seems most severe when specimens are cured

under water or in humid air. But specimens cured in dry condition undergo shrinkage.

Ozawa (2013) studied on hydration product and expansive energy of

expansive mortar at different curing temperatures. He concluded that the expansive

energy at higher temperature was more than at lower temperature. From Differential

Scanning Calorimeter (DSC) and Scanning electron Microscope (SEM) observation,

it was confirmed that AFt change to AFm at 50oC (Figure2.1)

12

Figure 2.1SEM observation on expansive mortar at50oC (Ozawa, 2013)

Iijima et al. (2013) studied about performance of concrete with expansive

additive for massive concrete. The results showed that expansive concrete introduce

pre-stress and pre-strain depending on type of cement and curing condition. Chemical

Pre-stress lost due to high temperature history but chemical pre-strain still occur.

(Figure 2.2)

Figure 2.2 Chemical pre-stress and chemical pre-strain of expansive

concrete(IIjima et al.2013)

13

2.3 Prediction Model for Cracking Age of Concrete

Dung (2010) proposed a formula to predict cracking age of expansive concrete.

Analysis can be divided into two periods, the expansion period and the shrinkage

period:

Expansion period

Stress strain relation (Hook’s law) for reinforcing steel:

( ) ( ) (2.1)

Stress strain relation (Hook’s law) for concrete:

( ) ( ) ( ) (2.2)

Where:

( ) : Stress produced in steel bar at any time t during curing time

( ) : Stress produced in concrete at any time t during curing time,

: Modulus of elasticity of steel, (MPa)

( ) : Modulus of elasticity of concrete at any time t, (MPa)

: Age of concrete, (days)

During this expansion period, the compression in concrete is balanced by the tension

in the reinforcement or restraining object as described in the force equilibrium

equation Eq.(2.3).

( ) ( ) (2.3)

Where:

= cross-sectional area of steel bar,

= cross-sectional area of concrete,

Substitution of equation (2.1) and equation (2.2) into the force equilibrium equation

(2.3) give the value of elastic strain (εc,e) in concrete during the expansion period as

below equation (2.4).

14

( ) ( ) ( ) (2.4)

Where:

= restraining steel ratio and ( ) )(tE

E

c

s

strain produces compressive stress of steel bar is:

( ( ) ( ) ( ) ( ) ( )).

Stress strain relation (Hook’s law) for reinforcing steel:

( ) ( ( ) ( ) ( ) ( ) ( ))

Eq.(2.5)

Stress strain relation (Hook’s law) for concrete:

( ) ( ) ( ) (2.6)

Force equilibrium in case of shrinkage:

( ) ( ) (2.7)

Substitution of equation (2.4), equation (2.5) and equation (2.6) into the force

equilibrium equation (2.11) give the elastic tensile strain of concrete as in equation

equation (2.12).

( ) )(. tn

)(.1 tn( ( ) ( ( )) ( ) ( ))

(2.8)

The limitations of this method are following:

The prediction requires value of tensile creep.

Ignoring the tensile creep makes the prediction of cracking age less precise.

Net restrained expansion must be determined by testing.

15

2.4 Prediction Model of Net Expansion

To predict net expansion, the net expansion after 7 days of curing, Dung(2010)

proposed the following equation:

( ( ) )

( ) (2.9)

Where:

: Net expansion after 7 days curing, μ

: Amount of Hyper expansive additive, kg/m3

: Amount of fly ash, %

:Restraining steel ratio, %

The limitations of this method are as follows:

The method was validated only for concrete with hyper expansive additive.

The method was compared with concrete which has w/c =0.5

16

2.5 Design and Test Method

ASTM C878 (1995) recommended the use of specimens with size 76x76x254

mm. The 10-mm diameter threaded-rod is used as a restraining body. The restrained

expansion is measured with a length comparator as shown in Figure2.3 to Figure 2.5

Figure 2.3 Geometry and size of specimen according ASTM C878

17

Figure 2.4 Mold preparation and specimen casting according ASTMC878

Figure 2.5 Measuring restrained expansion by a length comparator

JIS A 6202 (1997) recommended the use of specimens with size

100x100x360 mm. The 11- mm round rod is used as a restraint. Restrained expansion

is measured with a length comparator as shown in Figure2.6 to Figure 2.7

Figure 2.6 Restraining device for JIS A6202

18

Figure 2.7 Length measuring instrument for JIS A6202

Figure 2.8 Length measuring instrument for JIS A6202

(Image from http://www.kanto-ts.co.jp/)

19

ACI 223R-10 (2010) proposed estimation of member expansion for ettringite-

based system and calcium hydroxide-based system in Figure2.9 and Figure2.10,

respectively.

Figure 2.9 Estimation of member expansion for an ettringite-based system

[ACI 223-10]

Figure 2.10 Estimation of member expansion an calcium hydroxide based

system [ACI 223-10]

20

2.6 Internal Curing

Kinaanath (2013) studied about curing sensitivity of concrete with internal

curing by using bottom ash partial replacement in fine aggregate and found that the

use of bottom ash reduced curing sensitivity of concrete, reduced autogenous

shrinkage of mortar and concrete, and could be used as an effective internal curing.

Moreover total shrinkage of concrete was reduced with the use of 10% bottom ash

replacement.

Golias et al. (2012) studied an influence of moisture of light weight aggregate

(LWA) on internal curing efficiency. The result shown that use of oven dry LWA in

mixture is able to absorb water from paste during setting. The water absorbed by the

LWA can returned as internal curing water to the concrete. By taking absorption of

LWA into account for adjusting moisture, it was possible to get internal curing

benefit.

Kasemchaisiri (2008) studied an effect of bottom ash on fresh and hardened

properties of a self-compacting concrete (SCC). It was found that increasing of

bottom ash induces more shrinkage because of increase of porosity in concrete due to

the increase of bottom ash. However, at 10% replacement of bottom ash in fine

aggregate, 56-day strength was improved. It was reasonable to conclude that the

optimum replacement for the tested bottom ash was about 10% by weight of total fine

aggregate.

Barrett et al.(2015) reported the internal curing concrete used in bridge deck

as shown in Figure 2.11. It is note that the placement and finishing of internal curing

concrete is the same as conventional concrete. It is expected that the internally cured

bridge deck achieve reduction in cracking and improvement in permeability.

21

Figure 2.11 Internally cured bridge deck being placed in 2013 on US 150 over Lost

River in Orange County, Indiana [Barrett et al.(2015)]

22

Chapter 3

Research Methodology

3.1General

This research focused on standing restrained expansion of expansive concrete

with different expansive additives, and finding a design method for estimating

suitable dosages of expansive additives. 5 expansive additives were tested. Internal

curing by partial replacement by bottom ash in fine aggregate was tested. The

experimental program is shown in Figure 3.1

Figure 3.1 Experimental program

3.2 Materials

3.2.1 Cement

Ordinary Portland cement(OPC) was used in this study. Chemical composition

of the cement is shown in Table 3.1

3.2.2 Fly ash

High calcium fly ash(FA) from Mae Moh power plant in lampang province,

Thailand, was used. Chemical composition test results of the fly ash are shown in

Table 3.1.

23

3.2.3 Expansive Additive

Five expansive additives with different chemical composition were used in

this study. The test results are shown in Table 3.1

Table 3.1 Chemical composition of powder materials.

Material SiO2 Al2O3 Fe2O3 CaO MgO SO3 K2O Na2O

Name (%) (%) (%) (%) (%) (%) (%) (%)

OPC1 20.02 5.13 3.21 64.56 2.13 2.88 0.43 0.25

FA 37.05 20.48 13.55 16.26 2.69 1.83 2.30 0.87

OEA 3.96 2.01 1.43 66.94 0.64 14.70 0.12 0.12

HEA 0.00 0.54 0.81 72.06 0.60 12.91 0.02 0.09

SEA 0.18 4.61 0.88 54.59 4.08 24.42 0.23 0.15

FEA 7.47 9.89 2.67 47.54 1.95 20.38 0.38 0.19

CEA 0.00 17.12 0.04 47.47 0.17 30.74 0.00 0.10

3.2.4 Aggregates

3.2.4.1 Fine Aggregate

Natural river sand(S)from Ayutthaya province was used as normal fine

aggregate in all experiments. Bottom ash (BA) was used as internal curing substance

for the experiment of effect of internal curing on expansion and shrinkage of

expansive concrete. Gradation of fine aggregate is shown in Figure 3.2. Bottom ash

used in this study was sieved by Sieve no.4 before used in the experiment.

Figure 3.2 Gradation of fine aggregate

0%

20%

40%

60%

80%

100%

120%

3/8" #4 #8 #16 #30 #50 #100 Pan

pass

ing p

erce

nta

ge(

%)

SandBottom AshUpper limitLower limit

24

3.2.4.2 Coarse Aggregate

A well-graded crushed limestone with a maximum size of 19 mm (G) from

Supanburi province, Thailand, was used as the coarse aggregate in all experiments in

this study.

25

3.3 Mix Proportion

Table3.2 Concrete mix proportion

Designation OPC1 FA EA S BA G W

kg/m3 kg/m

3 kg/m

3 kg/m

3 kg/m

3 kg/m

3 kg/m

3

SE

A

FA00SEA20 345 0 20 806 1024 183

FA00SEA30 335 0 30 806 1024 183

FA20SEA20 264 71 20 806 1024 177

FA20SEA30 254 71 30 806 1024 177

FA20SEA40 244 71 40 806 1024 177

FA30SEA15 230 105 15 806 1024 175

FA30SEA20 225 105 20 806 1024 175

FA30SEA30 215 105 30 806 1024 175

FA30SEA40 205 105 40 806 1024 175

FE

A

FA00FEA20 345 0 20 806 1024 183

FA00FEA30 335 0 30 806 1024 183

FA20FEA20 264 71 20 806 1024 177

FA20FEA30 254 71 30 806 1024 177

FA30FEA15 230 105 15 806 1024 175

FA30FEA30 215 105 30 806 1024 175

HE

A

FA00HEA20 345 0 20 806 1024 183

FA20HEA20 264 71 20 806 1024 177

FA20HEA15 268 67 15 814 1026 175

FA20HEA5 276 69 5 814 1025 175

FA30HEA20 231 99 20 811 1021 175

FA30HEA15 235 101 15 811 1021 175

FA30HEA10 238 102 10 810 1021 175

FA30HEA5 242 104 5 810 1020 175

OE

A

FA00OEA15 335 0 15 823 1037 175

FA00OEA20 345 0 20 806 1024 183

FA00OEA20BA10 345 0 20 725 81 1024 183

FA00OEA30 320 0 30 823 1037 175

FA00OEA40 310 0 40 823 1037 175

FA20OEA20 264 71 20 806 1024 177

FA20OEA20BA10 264 71 20 725 81 1024 177

FA30OEA15 209 96 15 809 1020 175

FA30OEA30 224 96 30 809 1020 175

FA30OEA40 214 96 40 809 1020 175

CE

A

FA00CEA20 345 0 20 806 1024 183

FA20CEA20 264 71 20 806 1024 177

26

3.4 Method of Testing

3.4.1 Setting Time of Concrete

Specimens with a cross sectional area of 150x150 mm2 were used for testing

setting time of concrete , conforming to ASTM C 403. Stiffening time, initial setting

time and final setting time were tested. The apparatus for testing is shown in Figure

3.3

Figure 3.3 Concrete setting time test apparatus

3.4.2 Compressive Strength of Concrete

Cylindrical specimens with size 150x300 mm, conforming to ASTM C39

were used to test compressive strength of concrete. The compressive strength testing

machine is shown in Figure 3.4.

27

Figure 3.4 compressive test machine

3.4.3 Free Expansion and Free Shrinkage of Concrete

Specimens with the size of 75×75×250 mm3 were used for free

expansion/shrinkage test. The test conforms to ASTM C157 - 08. Initial lengths were

recorded at 8 hours after mixing. The specimens were cured for 7 days after removing

the mould and subsequently exposed to drying environment (28oC and 75% relative

humidity) as shown in Figure 3.5(a) Afterwards, the free shrinkage of specimens was

periodically measured. Figure 3.5(b) shows the specimens and measurement of free

expansion/shrinkage.

Figure3.5(a) Specimens for free expansion/shrinkage test

28

Figure3.5(b) Length measurement

Figure 3.5 Measurement of free expansion/free shrinkage

3.4.4 Internally Restrained Expansion

3.4.4.1 Apparatus for Restrained Expansion Test

A new set of restraining apparatus shown in Figure 3.6 and Figure 3.7 was

designed and employed for the measurement of restrained expansion in this study.

The key feature of the apparatus is that the conventional deformed bar for

construction is used as a restraint. When compared with other standard tests such as

ASTM C878 or JIS 6202, the use of the conventional rebar provides similar condition

to the real RC and also allows a convenient prefabrication of the apparatus. The

restraining ratio in each specimen can also be adjusted by selecting appropriate size

and number of steel bars. In this study, four different restraint ratios; namely, 0.785%

(one DB10 rebar), 1.131% (one DB12 rebar), 1.571% (two DB10 rebars), and 2.262%

(two DB12 rebars) were used in the test program. The steel end plates with the

thickness of 15 mm were used to prevent excessive difference in expansion between

the section center (at the restraining rebar) and near the edge of the section.

29

Figure 3.6(a) Steel bar for restraining

Section top view

Figure 3.6(b) End plate

Figure 3.6(c) Installation in the mold

Dimensions Size(mm)

A 400

B 350

C 100

D 100

E 50

F 50

G 15

H 10

Figure3.6 Geometry and size of specimens for measurement of internally restrained

expansion

30

Figure 3.7 Installation of strain gages on restraining rebars and preparation of

formworks before casting

Figure 3.8 Moist curing by wet clothes and plastic sheets until the age of 7 days

3.4.4.2 Measurement of Restrained Expansion

Concrete samples with a cross-sectional area of 100x100 mm and length of

350 mm were used for the restrained expansion test. In the production of the

specimens, concrete was cast into well-prepared steel formwork in which the

restraining apparatus described in topic 3.4.4.1 was installed beforehand. Two

31

electrical wire-type strain gages were attached to the mid length of the restraining

steel bar in order to provide continuous readings of expansion. In the case that two

rebars were used, one strain gage was attached to each rebar. The strain gages were

then connected to data acquisition equipment (DAQ) and the measurement of strain

was initiated before the casting. Figure 3.6 shows the formwork and apparatus just

before the casting of the concrete.

The casing was performed in gentle manner to prevent any damage that may

be induced to the strain gages. Good compaction was provided to eliminate air

bubbles and to ensure that the concrete can satisfactorily fill the formwork. The

formwork was removed at 7 hours after casting. The specimens were then cured in

moist condition (wrapped by wet clothes and then covered with plastic sheets) as

shown in Figure3.7. The strain measurement was continuously performed. In this

study, the expansion of specimens from the age of 8 hours after casting will be

considered and discussed. Each expansion value was obtained from an average of

readings from two strain gages. It was checked that the difference of the two readings

was, in all cases, less than 10%. During the testing process, environmental

temperature was controlled to be in the range from 27.5oC to 30

oC.

32

Chapter 4

Result and Discussions

4.1 Effect of Type and Amount of Expansive Additive

Figure 4.1 shows examples of development of restrained expansion. The

expansion was rapidly induced during the first three days and became stable (almost

constant) subsequently. These results suggested that, for expansive concrete,

sufficient curing must be provided at least 2 days to allow the complete reaction of the

expansive additives. It should be noted that longer curing (for instance, 7-day curing)

can help reducing subsequent shrinkage and thus risk of shrinkage crack.

(a) Restrained expansion for FA20SEA20 under different restraint ratios

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7

Res

trai

nt

expan

sion

,µε

Age, days

FA20SEA20

0.785% 1.131% 1.571%

2.262% 3.142%

Restraint ratios

33

(b) Restrained expansion for FA20SEA20 under different restraint ratios

(c) Restrained expansion for FA20HEA20 under different restraint ratios

Figure 4.1 Example of development of restrained expansion

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7

Res

trai

nt ex

pan

sio

n,µ

ε

Age, days

FA20FEA20

0.785% 1.131%

1.571% 2.262%

3.142%

Restraint ratios

0

20

40

60

80

100

120

140

160

180

200

0 1 2 3 4 5 6 7

Res

trai

nt

expan

sion

,µε

Age, days

FA20HEA20

0.785% 1.131%

1.571% 3.142%

Restraint ratios

34

Figure 4.2 summarizes the restrained expansions, at the age of 7 days, of

expansive concretes with different amounts of fly ash and expansive additives under

moist curing condition. Figures 4.2(a-d) show the restrained expansion of specimens

with SEA, FEA, OEA, and HEA, respectively. Comparing these graphs, it is obvious

that the use of different EAs gives different degrees of expansion. Among expansive

concretes without fly ash, the one with HEA shows the highest expansion at the same

dosage of EA and followed by the ones with OEA, SEA, and FEA, respectively.

Tendency is also the same for the case of expansive concrete with fly ash. The

difference in the expansion obtained from the use of different expansive additives

may result from the difference in chemical composition, phases of chemical

components, and fineness of each expansive additive. This point will be further

investigated in the future.

(a) Specimen with SEA

0

50

100

150

200

250

300

0 5 10 15 20 25 30 35 40

Res

trai

ned

ex

pan

sion

(1.5

71%

), μ

ε

Amount of expansive additive, kg

SEA,FA0%

SEA,FA20%

SEA,FA30%

35

(b) Specimen with FEA

(c) Specimen with OEA

0

50

100

150

200

250

300

0 5 10 15 20 25 30 35 40

Res

trai

ned

ex

pan

sion

(1.5

71

%),

με


FEA,FA0%

FEA,FA20%

FEA,FA30%

0

50

100

150

200

250

300

0 5 10 15 20 25 30 35 40

Res

trai

ned

ex

pan

sion

(1.5

71%

), μ

ε


OEA,FA0%

OEA,FA30%

36

(d)specimen with HEA

Figure 4.2 restrained expansion of specimen with 1.571% restraint

The results in Figure 4.2 also indicate that, in all cases (both expansive

concrete with and without fly ash, the restrained expansion (restraining ratio =

1.571%) have somewhat linear relationship with the dosage of expansive additive (in

kg/m3). This tendency was found to be also true in the case of other restraining ratios

(0.785%, 1.131%, and 2.262%) as described in section 3.4.4. This information is

useful for the estimation of a required dosage of expansive additive that produces a

specific value of expansion in a given restrained condition.

For all types of expansive additive used, the presence of fly ash increases the

restrained expansion at 7 days. At the same dosage of expansive additive, concrete

samples with 30% fly ash give clearly higher expansion than the concrete with 20%

fly ash replacement and also the concrete without fly ash, respectively. This tendency

shows that fly ash has good compatibility with all types of expansive additives. This

phenomenon is still not fully explainable at present. However, it is believed that the

higher expansion may results from at least three following reasons. The first reason is

the higher Alumina content (Al2O3) in fly ash which may allow more formation of

0

50

100

150

200

250

300

0 5 10 15 20 25 30 35 40

Res

trai

ned

ex

pan

sion

(1.5

71%

), μ

ε


HEA,FA20%

HEA,FA30%

37

ettringite ((CaO)6(Al2O3)(SO3)•32H2O) and the second reason is the lower early age

stiffness of cement-fly ash paste system which allows more crystal growths of

expanding products. The third is possibly the delay of reaction of expansive additive

by fly ash.

4.2Expansion Efficiency

In practice, the selection of suitable expansive additive and the estimation of

required dosage are key procedures in the application of expansive concrete. It is very

often that the performance of each expansive additive must be compared, not only for

engineering judgment but also for cost comparison. The use of expansive additive in

fly ash concrete may also sometimes be questioned. To response to these challenges,

the new term ‘expansion efficiency’ is introduced to quantitatively illustrate the

efficiency of each expansive paste system. In this study, the ‘expansion efficiency’ is

defined as the expansion created by a unit amount of expansive additive in a given

condition. The expansion efficiencies can therefore be calculated as slopes of graphs

in Figure 4.2.

Figure 4.3 Expansion efficiency of each expansive additive

(Restraint ratio =1.31%, w/b=0.5)

Figure 4.3 compares the expansion efficiencies of the expansive additives

tested in this study, which allows a simple comparison of different types of expanding

paste system. For instance, based on Figure 4.3, it can be simply concluded that, at

2.5

4.5

6.6 7.1 6.9

4.6

5.7

7.3

8.3 8.8

6.3 6.4

8.1

9.5

0.0

2.0

4.0

6.0

8.0

10.0

12.0

FEA SEA OEA HEA CEA

1.3

1%

res

trai

ned

ex

pan

sion

effi

cien

cy,(

µƐ

/kg)

FA0%

FA20%

FA30%

38

w/b ratio of 0.5, using fly ash at 30% of total binder increases the expansion

efficiency of the concrete by at least 15%(when compared to concrete without flyash).

It is noted however that the expansion efficiency in Figure 4.3 was derived

from the test results of concrete with w/b ratio of 0.5 and restraint ratio of 1.571%.

The expansion efficiency may be substantially changed if the w/b ratio or restraint

ratio is changed. The effect of restraint ratio on restrained expansion is discussed in

the next section.

4.3 Effect of Restraint Ratio on Restrained Expansion

Figure 4.4 shows the relationship between restrained expansion and amount of

SEA in the case of concrete with 20% fly ash replacement under different restraint

ratios. It is clear that the relationship between dosage of expansive additive and the

restrained expansion seems to be linear for the range of restraint ratio from 0.785% to

2.263%. The slope of the graph (and thus expansion efficiency) reduces when the

restraint ratio increases.

Figure 4.4 Restrained expansion of SEA with 20% FA under different restraint

ratios

Figure 4.5 shows an example of a reduction of expansion efficiency (fly ash

concrete with 20% fly ash replacement and SEA) due to the increase of restraint ratio.

The reduction of restrained expansion due to the increase of restraint seems to be non-

linear.

0

50

100

150

200

250

300

0 10 20 30 40 50

Res

trai

ned

ex

pan

sion

, μ

ε

Amount of SEA, kg

0.785%

1.131%

1.571%

2.263%

39

Figure 4.5 Expansion efficiency of SEA with FA20% on different restraint

ratios

Figure 4.6(a-d) shows the effect of restraint ratio on restrained expansion at 7

days of all expansive concretes tested in this study. Similar trend could be obtained

for all cases. From the results in Figure 4.6(a-d), the relative expansion was calculated

as a normalized expansion to the expansion at the restraint ratio of 1.131% . Figure

4.7 shows the relative expansion obtained from the test results.

(a)Specimens with SEA

6.1 5.7

5.1

3.8

0

1

2

3

4

5

6

7

0.785% 1.131% 1.571% 2.263%

Ex

pan

sion

eff

icie

ncy

, μ

ε/kg.

Restraint ratio, %

SEA,FA20%

0

50

100

150

200

250

0.0% 1.0% 2.0% 3.0% 4.0%

Res

trai

ned

ex

pan

sion

, μ

ε

Restraint ratio,%

FA00SEA20

FA00SEA30

FA20SEA20

FA20SEA30

FA30SEA15

FA30SEA20

FA30SEA30

40

(b) Specimens with FEA

(c)Specimens with HEA

0

20

40

60

80

100

120

140

160

180

0.0% 1.0% 2.0% 3.0% 4.0%

Res

trai

ned

ex

pan

sio

n, μ

ε

Restraint ratio,%

FA00FEA20

FA00FEA30

FA20FEA20

FA20FEA30

FA30FEA30

0

50

100

150

200

250

0.0% 1.0% 2.0% 3.0% 4.0% 5.0%

Res

trai

ned

ex

pan

sion

, μ

ε

Restraint ratio,%

FA20HEA20 FA20HEA15FA20HEA5 FA30HEA20FA30HEA15 FA30HEA10FA30HEA5

41

(d)Specimens with OEA

Figure 4.6 Effect of restraint ratio on the restrained expansion at 7days

(a) Specimens with SEA

0

50

100

150

200

250

300

350

400

0.0% 1.0% 2.0% 3.0% 4.0% 5.0%

Res

trai

ned

ex

pan

sion

, μ

ε

Restraint ratio,%

FA0OEA30

FA30OEA30

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

0.0% 1.0% 2.0% 3.0% 4.0%

Rel

ativ

e e

xpan

sion

(1.1

31%

).

Restraint ratio,%

FA00SEA20

FA00SEA30

FA20SEA20

FA20SEA30

FA30SEA15

FA30SEA20

FA30SEA30

42

(b) Specimens with FEA

(c) Specimens with HEA

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

0.0% 1.0% 2.0% 3.0% 4.0%

Rel

ativ

e e

xpan

sion

(1.1

31%

) .

Restraint ratio,%

FA00FEA20

FA00FEA30

FA20FEA20

FA20FEA30

FA30FEA30

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.0% 1.0% 2.0% 3.0% 4.0% 5.0%

Rel

ativ

e e

xpan

sion(1

.131%

) .

Restraint ratio,%

FA20HEA20 FA20HEA15FA20HEA5 FA30HEA20FA30HEA15 FA30HEA10FA30HEA5

43

(d) Specimens with OEA

Figure 4.7 Relative expansion

4.4 Effect of Internal Curing

4.4.1 Effect of Internal Curing on Free Expansion

By adding bottom ash into the normal expansive concrete to induce internal

curing, it was found that a replacement of 10% in fine aggregate could increase 7-day

free expansion by 14% (Figure 4.8) when compared to the expansive concrete without

BA.

This effect is also observed in fly ash expansive concrete. The results in

Figure 4.9 show that the 7-day expansion increases by 24% in fly ash expansive

concrete with BA10% when compared to the fly ash expansive concrete without BA.

For the effect of fly ash on 7-day free expansion of mixtures with no BA,

Figure 10 shows that the replacement of 20% fly ash in total binder (FA20EA20)

increases the expansion by approximately15% when compared to expansive concrete

with no fly ash (FA00EA20).

0

0.2

0.4

0.6

0.8

1

1.2

1.4

0.0% 1.0% 2.0% 3.0% 4.0% 5.0%

Rel

ativ

e e

xpan

sion

(1.1

31%

) .

Restraint ratio,%

FA0OEA30

FA30OEA30

44

Figure 4.8 Effect of BA on free expansion of normal Expansive concrete

Figure 4. 9 Effect of BA on free expansion of Fly Ash Expansive concrete

However, for mixtures with BA an increase of 25% expansion over the

mixture without fly ash was obtained when using fly ash with BA (Comparing

0

50

100

150

200

250

300

350

400

450

0 1 2 3 4 5 6 7

Fre

e ex

pan

sion

(µ

ε)

Age (days)

FA00OEA20

FA00OEA20BA10

0

100

200

300

400

500

600

0 1 2 3 4 5 6 7

Fre

e ex

pan

sion

(µ

ε)

Age (days)

FA20OEA20

FA20OEA20BA10

45

FA20EA20BA10 with FA00EA20BA10). Moreover, the results of mixtures with

10%BA (FA00EA20BA10) and the mixture with 20%FA (FA20EA20), show that the

7-day free expansion can increase about 14% and 15%, respectively when compared

to the control mixture with no FA and no BA(FA00EA20).

The synergy between BA and FA significantly improves expansion of the

mixture with both BA and FA when compared to the effect of only fly ash or only

bottom ash. If can be seen that the tested 7-day expansion of expansive concrete with

both BA and FA increases up to 43% when compared to normal expansive concrete

with no BA and no FA (Figure 4.10).

Figure 4.10 Summary results of 7-day free expansion of expansive concrete with FA

and BA

4.4.2 Effect of Internal Curing on Restrained Expansion

Internal curing by using bottom ash at 10% replacement in fine aggregate can

increase restrained expansion on the 7th

day by 9% when compared to normal

100%

114% 115%

143%

0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

200%

% I

ncr

ease

7th day free expansion

46

expansive concrete with no BA (Figure 4.11). Also, as shown in Figure 12, the

expansion increased by about 20% for fly ash expansive concrete with BA.

Figure 4.11 Effect of BA on 7-day restrained expansion of normal expansive concrete

Figure 4.12 Effect of BA on 7-day restrained expansion of Fly Ash-expansive

concrete.

0

50

100

150

200

250

300

0 1 2 3 4 5 6 7

1.1

3%

Res

trai

ned

ex

pan

sion

(µ

ε)

Age (days)

FA00OEA20

FA00OEA20BA10

0

50

100

150

200

250

300

0 1 2 3 4 5 6 7

1.1

3%

Res

trai

ned

ex

pan

sion

(µ

ε)

Age (days)

FA20OEA20

FA20OEA20BA10

47

Figure 4.13 Summary results of 7-day restrained expansion of expansive concrete

with FA and BA

Figure 4.13 shows that using both FA and BA increases 7-day restrained

expansion in expansive concrete, similar to the results in free expansion condition.

The application of both FA and BA gain more efficiency by increasing the restrained

expansion to 71% when compared to the reference mixture with no BA and FA. The

reason that bottom ash can increase expansion of the expansive concrete is probably

because bottom ash, by internal curing effect, provides water for the reaction of the

expansive agent at the inner part of the concrete where curing water is not possible to

be supplied from the normal curing from outside.

4.4.3 Effect of Internal Curing on Free Shrinkage

It is noted that the effectiveness of shrinkage compensation also depends on

the amount of shrinkage of the mixture. If expansion of the mixture is improved, but

100% 109%

142%

171%

0%

20%

40%

60%

80%

100%

120%

140%

160%

180%

200%%

In

crea

se

7th day restrained expansion

48

shrinkage of the mixture is on the other hand much higher, the shrinkage

compensation may not be so effective. It is therefore necessary to evaluate the

shrinkage behavior of the expansive concrete for a more relevant evaluation. As

bottom ash is porous with high water retainability, it is expected to reduce autogenous

shrinkage but may increase drying shrinkage of the concrete. The results in Figure

4.14 show the subsequent shrinkage after curing (after 7-day expansion). The

shrinkage up to the age of 49 days of expansive concrete with internal curing is

similar to that of the normal expansive concrete. However, at long term, the shrinkage

of expansive concrete with internal curing by BA becomes slightly larger than that of

the normal expansive concrete. This may be because, when the bottom ash which has

high porosity is added into the concrete, the microstructure is not as dense as that of

the concrete with natural fine aggregate. The moisture can thus evaporate and migrate

out of the sample more easily. This is more obvious at long-term.

Figure 4.14 Total shrinkage of expansive concrete with BA

0

100

200

300

400

500

600

0 7

14

21

28

35

42

49

56

63

70

77

84

91

98

105

112

119

Fre

e sh

rinkag

e (µ

ε)

Age (days)

FA00OEA20

FA00OEA20BA10

FA20OEA20

FA20OEA20BA10

49

Figure 4.15 Total length change of expansive concrete with BA

Figure 4.15 show that total length change at long term of expansive concrete

with bottom ash is approximately same as that of the expansive concrete without

bottom ash.

Higher expansion of expansive concrete with fly ash was probably due to the

delaying effect of fly ash on the reaction of expansive additive, higher alumina

content of the fly ash and lower stiffness of pastes during expansion period, inducing

more opportunity to expand. More expansion of expansive concrete with bottom ash

was also found due to mitigating autogenous shrinkage and supply of water for

reaction of the expansive additive by internal curing. Future investigations are

required for confirmation of these mechanisms.

The experimental findings indicate that internal curing can potentially be

applied to increase efficiency of expansive concrete however the balance between the

enhanced expansion and the subsequent drying shrinkage must be carefully

considered. It should be noted that since there is still no study done on the effect of

bottom ash on expansion and shrinkage behavior of expansive concrete, for real

application in the future, it is necessary to investigate the mechanisms on how fly ash

-100

0

100

200

300

400

500

600

0 7

14

21

28

35

42

49

56

63

70

77

84

91

98

105

112

119

Len

gth

Chan

ge

(µε)

Age (days)

FA00OEA20

FA00OEA20BA10

FA20OEA20

FA20OEA20BA10

50

affects the expansion of expansive concrete as well as the quantitative evaluation of

expansion of internally cured expansive concrete under different degrees of restraint

for possible design in the future.

51

Chapter 5

Proposed Design Approach

5.1 General Procedures

In this section, a design approach which is more suitable to the use of

expansive concrete by applying expansive additive is developed and discussed. This

design focuses on the use of expansive concrete as the shrinkage-compensating

concrete. The main objective of the design approach in this case is therefore to

determine the suitable amount of expansive additive that produces sufficient

restrained expansion in a member so that the shrinkage crack can be prevented.

The design can be divided into three steps namely:

Step 1: Determination of required member expansion

Step 2: Determination of required prism expansion

Step 3: Estimation of required dosage of expansive additive

It is noted here that this proposed design approach has been developed by

considering axial members with concentric stress. The design may have limited

applicability to other cases such as RC members with asymmetric reinforcement.

5.2 Required Member Expansion

For a given member under consideration, the member expansion (exp,res)

required for the shrinkage compensation can be calculated as shown in Eq 2.8. A full

explanation of the equation is given by Dung(2010) . In order to use the equation, the

test data or model for free shrinkage and cracking strain capacity of concrete is

necessary. The calculation of the required member expansion may also be simplified

ignoring tensile creep (p,tension is assumed to be zero).

5.3 Necessary Restrained Prism Expansion

From the required restrained member expansion, the necessary restrained

prism expansion (restrained expansion of the specimens) is to be determined. The

calculation methods based on the experimental results illustrated in Figure 4.7 is

proposed. Figure 5.1 is the relationship between the relative expansion and restrained

prism expansion of the samples (including all types of expansive additives) tested in

52

this study. In Figure 5.1, the design curve with 99.99% degree of confidence is

created. The result suggested that, although slight difference could be observed for

different expansive additives, the same design curve can be reasonably applied.

Figure 5.1 Relationship between relative expansion and restraint ratio

(all types of expansive additives)

Figure 5.2 is the relationship between the member expansion and the prism

expansion. The slope of line for each restraint ratio was obtained from the value of the

design curve with 99.99% confidence in Figure 5.1. Figure 5.2 can be used to estimate

the required restrained prism expansion.

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0% 1% 2% 3% 4%

Rel

ati

ve

exp

an

sion

Restraint ratio

Tested result

99.99% confidence

53

Figure 5.2 Relationship between member expansion and prism expansion based on

experimental results in this study

5.4 Determination of Expansive Additive

Once the required member expansion is estimated, a dosage of expansive

additive necessary for creating required expansion can then be calculated from the

relationship between dosage of expansive additive and the restrained expansion

(similar to those in Figure 4.2). Based on the proposed test methods, the relationship

between dosage of expansive additive and restrained expansion at restraint ratio of

1.131% can be obtained and used for the design.

Note that the relationship is dependent on not only the type of expansive

additives but also the water-to-cement ratio of the concrete to which the expansive

additive is added. Such information should be provided by suppliers of the expansive

additives.

0

0.02

0.04

0.06

0.08

0.1

0 0.02 0.04 0.06 0.08 0.1

Mem

ber

exp

an

sion

, %

Restrained concrete prism expansion(1.131%), %

99.99%

confidence

54

Chapter 6

Conclusion and Recommendations

6.1General

1.) It was found that, for all four types of expansive additives tested in this study,

the restrained expansion has a linear relationship with the dosage of expansive

additives.

2.) Fly ash can increase the expansion of expansive concrete.

Lower restrained expansion could be obtained when restraint ratio is higher.

The relationship between restrained expansion and restraint ratio is non-linear.

3.) Based on the proposed test method and the experimental findings, the design

procedure which is more suitable for the use of expansive additive is

proposed.

4.) Internal curing by replacing 10% of fine aggregate with bottom ash can

contribute to higher early age expansion in both free condition (up to 14% of

the mixture without bottom ash) and restrained condition (up to 9% of the

mixture without bottom ash). Synergy between 10% bottom ash replacement

in fine aggregate and 20% fly ash replacement in binder can increase more

expansion in both free condition and restrained condition, up to 43% and 71%

of the mixture without bottom ash, respectively. So it is possible to reduce

risk of early age shrinkage cracking when using expansive concrete with

internal curing.

5.) After 7 days of expansion, mixtures with bottom ash tend to have larger total

shrinkage when compared to the corresponding mixtures without bottom ash.

The long-term total length change of expansive concrete with bottom ash is

similar to that of the expansive concrete with no bottom ash. The experimental

findings indicate that bottom ash can potentially be applied to increase

expansion of expansive concrete however the balance between the enhanced

expansion and the subsequent drying shrinkage must be carefully considered.

55

6.2 Recommendation for Further Study

• The effect of creep and relaxation of concrete might be included to the future

study for more understand expansive concrete behavior under restraint

condition.

• Effect of others concrete chemical admixture such as water reducer, retarder

and superplasticizer might be included on expansion of expansive concrete for

ensure that will not have negative result.

56

References

ACI committee 223. ACI 223R-10 Guide for the Use of Shrinkage-Compensating

Concrete. American concrete Institute, 2010.

Dung Tien Nguyen. Prediction of shrinkage cracking age of concrete with and

without expansive additive. Songklanakarin Journal of Science and technology,

2010.volumn 35:pp469-480

H.Iijima,et al. Mechanical performance of expansive concrete in uniaxial tension test

with different cement types, ages, and curing conditions. Hokkaido University

Collection of Scholarly and Academic Papers (HUSCAP),2013

Japanese standard association. JIS A 6202 Expansive additive for concrete,1997

Kinaanath Hussain. Effect of cement types, mineral admixtures and bottom ash on

curing sensitivity of concrete. International Journal of Mineral, Metallurgy and

materials,2013.volume 20:p94

Mitsuo Ozawa,et al. Expansion and hydration product of expansive mortar at

different temperature. Third International Conference on sustainable Construction

Material and Technologies.2013

Nguyen Trong Lam, et al. Expansion and Compressive Strength of Concrete with

Expansive Additive. Research and Development Journal of the Engineering Institute

of Thailand, 2008. volume 19(Issue 2): pp. 40-49.

Peiyu Yan,Xiao Qin. The effect of expansive agent and possibility of delayed

ettringite formation in shrinkage-compensating massive concrete. Cement and

concrete research, 2000.volume31:pp.335-337

Ratchayut Kasemchaisiri,et al.Properties of self-compacting Concrete in corporating

Bottom ash as a Partial Replacement of fine aggregate.Science

Asia,2008.volum34:pp087-095

S.Nagataki,& H.Gomi. Expansive admixture(mainly ettringite).Cement and concrete

composite,1998. volume 20:pp163-170

57

Appendix

58

Appendix

Table A1 Setting time test results

Designation Slump Setting time (min)

(cm) Stiffening Initial Final

FA00SEA20 4 120 160 240

FA00SEA30 5 115 180 240

FA20SEA20 4 130 190 280

FA20SEA30 12 120 185 250

FA20SEA40 5.5 125 170 235

FA30SEA15 11 155 210 285

FA30SEA20 10 150 205 280

FA30SEA30 10 145 195 270

FA30SEA40 7 140 190 260

FA00FEA20 7 230 305 385

FA00FEA30 6 240 355 400

FA20FEA20 13.5 250 375 435

FA20FEA30 12.5 270 385 445

FA30FEA15 11 280 345 440

FA30FEA30 9.5 305 375 470

FA00OEA15 3.5 95 150 225

FA00OEA20 3.5 100 155 230

FA00OEA20BA10 3.5 120 150 220

FA20OEA20 3 125 160 260

FA20OEA20BA10 4 115 165 245

FA00CEA20 3 90 140 200

FA20CEA20 4 115 180 255

59

Table A2 Compressive strength test results

Designation Compressive strength (ksc)

3days 7days 28 days

FA00SEA20 181 351 424

FA00SEA30 225 280 370

FA20SEA20 176 293 400

FA20SEA30 210 263 383

FA20SEA40 229 324 377

FA30SEA15 195 235 392

FA30SEA20 202 240 400

FA30SEA30 193 230 383

FA30SEA40 204 267 316

FA00FEA20 279 346 407

FA00FEA30 304 362 386

FA20FEA20 226 269 354

FA20FEA30 210 243 326

FA30FEA15 170 210 300

FA30FEA30 174 212 323

FA00OEA15 204 299 401

FA00OEA20 265 300 353

FA00OEA20BA10 280 312 392

FA00OEA30 260 302 402

FA00OEA40 283 328 385

FA20OEA20 217 242 350

FA20OEA20BA10 238 299 389

FA30OEA15 201 279 353

FA30OEA30 141 190 301

FA30OEA40 225 273 374

FA00CEA20 287 320 347

FA20CEA20 192 288 330

60

Table A3 Internal restrained expansion, restraint ratio 0.79%

Designation Internal restrained expansion,0.79%(με)

1days 2days 3days 4days 5days 6days 7days

FA00SEA20 76 93 98 100 103 106 107

FA00SEA30 94 130 138 138 140 142 143

FA20SEA20 92 128 132 132 132 132 134

FA20SEA30 129 179 185 185 185 184 188

FA20SEA40 163 226 233 233 233 233 237

FA30SEA15 92 127 131 131 131 131 133

FA30SEA20 102 141 146 146 146 145 148

FA30SEA30 196 209 211 212 207 202 201

FA00FEA20 37 50 53 57 60 62 62

FA00FEA30 56 76 81 86 91 94 94

FA20FEA20 70 96 100 102 104 109 111

FA20FEA30 90 123 127 130 133 139 141

FA30FEA15 76 104 108 110 114 117 120

FA30FEA30 125 145 150 154 159 163 167

FA20HEA20 169 183 190 192 194 196 198

FA20HEA15 117 120 125 126 126 128 130

FA20HEA5 43 47 50 50 50 50 49

FA30HEA20 196 209 212 214 217 219 219

FA30HEA15 141 161 165 167 167 167 169

FA30HEA10 79 92 98 98 99 100 100

FA30HEA5 50 54 54 55 54 57 56

FA00CEA20 140 163 160 159 157 164 171

FA20CEA20 179 203 206 210 209 214 219

61




FA00SEA20 65 81 87 90 91 93 92

FA00SEA30 84 114 121 126 129 133 134

FA20SEA20 90 114 117 120 120 120 123

FA20SEA30 125 159 164 167 168 167 172

FA20SEA40 157 200 206 210 211 210 215

FA30SEA15 84 107 110 113 113 113 116

FA30SEA20 96 122 126 128 129 128 132

FA30SEA30 179 190 192 193 188 184 183

FA30SEA40 201 204 206 207 211 217 215

FA00FEA20 32 41 43 46 48 50 50

FA00FEA30 49 62 65 69 73 76 76

FA20FEA20 62 89 92 94 96 100 101

FA20FEA30 78 111 114 118 119 125 126

FA30FEA15 70 100 103 106 109 112 114

FA30FEA30 92 134 137 141 146 149 152

FA00HEA20 139 157 163 166 166 165 166

FA20HEA20 146 159 165 166 168 169 172

FA20HEA15 108 111 115 116 117 118 120

FA20HEA5 37 40 43 43 43 43 42

FA30HEA20 168 179 182 184 186 187 188

FA30HEA15 129 147 151 153 153 153 154

FA30HEA10 68 79 84 84 85 86 86

FA30HEA5 44 47 47 48 47 50 49

FA00OEA15 74 75 76 76 75 75 76

FA00OEA20 119 141 145 150 153 157 163

FA00OEA20BA10 125 147 152 161 165 170 177

FA20OEA20 211 213 216 216 226 227 232

FA20OEA20BA10 252 258 260 260 263 270 278

FA30OEA15 79 82 81 81 84 84 83

FA30OEA30 305 352 349 350 352 348 349

FA30OEA40 269 285 284 284 287 287 290

FA00CEA20 110 127 125 129 129 134 138

FA20CEA20 142 160 162 165 167 171 175

62




FA00SEA20 64 77 83 86 88 91 89

FA00SEA30 79 113 119 122 124 125 125

FA20SEA20 89 110 113 115 114 113 114

FA20SEA30 109 143 148 151 152 151 156

FA20SEA40 136 177 183 188 189 188 193

FA30SEA15 76 100 103 106 106 106 108

FA30SEA20 91 119 123 126 126 126 129

FA30SEA30 128 136 138 138 135 132 131

FA00FEA20 28 38 40 43 45 47 47

FA00FEA30 42 57 61 64 68 70 70

FA20FEA20 54 79 82 83 83 88 90

FA20FEA30 68 99 103 104 105 111 113

FA30FEA15 54 80 83 84 87 89 91

FA30FEA30 80 118 122 124 128 131 134

FA20HEA20 127 142 148 149 150 154 158

FA20HEA15 93 102 104 107 108 108 109

FA20HEA5 36 39 39 40 41 38 39

FA30HEA20 148 159 161 163 165 167 167

FA30HEA15 115 131 134 136 136 136 137

FA30HEA10 60 74 73 73 74 72 74

FA30HEA5 42 46 45 45 45 45 43

FA00CEA20 79 91 89 92 95 97 100

FA20CEA20 104 120 120 123 119 123 129

63




FA00SEA20 57 67 69 72 74 75 74

FA00SEA30 62 90 97 100 102 102 104

FA20SEA20 73 92 97 97 97 93 96

FA20SEA30 61 95 99 103 104 103 107

FA30SEA15 43 67 70 73 73 73 76

FA30SEA20 56 87 92 95 96 95 99

FA30SEA30 126 131 129 132 125 120 118

FA00FEA20 28 34 36 39 41 42 42

FA00FEA30 42 51 55 58 61 63 63

FA20FEA20 49 73 75 77 78 85 86

FA20FEA30 61 90 94 95 97 106 107

FA30FEA15 55 82 85 86 91 96 97

FA30FEA30 71 109 112 115 121 125 128


Designation Internal restraint expansion,3.14%(με)

1 2 3 4 5 6 7

FA20SEA20 63 82 84 85 86 76 82

FA20FEA20 42 62 62 63 65 73 73

FA20HEA20 95 107 113 114 116 116 120

FA20HEA15 75 88 88 91 88 94 97

FA20HEA5 22 25 25 25 28 27 25

FA30HEA20 113 125 126 127 126 125 127

FA30HEA15 103 117 121 118 118 118 118

FA30HEA10 47 54 59 60 59 59 58

FA30HEA5 25 32 32 33 34 33 32

FA00OEA30 111 113 120 123 127 126 128

FA30OEA30 135 147 152 156 156 158 159

64

Table A8 Free expansion

Designation Free expansion (με)


FA00SEA20 171 168 163 176 176 184 189

FA00SEA30 250 250 254 264 264 276 284

FA20SEA20 427 464 475 483 486 496 499

FA00FEA20 42.67 62.67 80 87 96 98.67 99

FA20FEA20 51.33 81.33 129.67 165 179 182.67 181

FA00HEA20 202 260 258 268 264 262 262

FA20HEA20 236 395 456 498 512 528 532

FA20HEA15 383 421 445 463 473 467 457

FA20HEA5 74 94 100 100 100 98 94

FA30HEA20 236 395 456 498 512 528 532

FA30HEA15 383 421 445 463 473 467 457

FA30HEA10 99 113 127 125 117 117 111

FA30HEA5 74 94 100 100 100 98 94

FA00OEA15 30 30 30 30 30 30 30

FA00OEA20 339 339 349 347 344 341 344

FA00OEA20BA10 357 357 331 387 376 373 392

FA00OEA30 540 560 568 572 572 572 572

FA20OEA20 419 392 400 379 397 424 395

FA20OEA20BA10 445 509 445 472 477 485 491

FA30OEA15 520 520 520 520 520 520 520

FA30OEA30 688 736 741 739 747 749 749

FA00CEA20 224 299 333 349 357 349 363

FA20CEA20 376 405 403 405 411 419 413

65

Table A9 Fine aggregate gradation

Sieve No.

Passing Percentage ASTM C33 Limit (%)

Sand Bottom Ash Upper Lower

3/8" 100.00% 99.05%

100.00% 100.00%

#4 95.49% 93.58%

100.00% 95.00%

#8 86.46% 85.24%

100.00% 80.00%

#16 69.91% 74.65%

85.00% 50.00%

#30 47.34% 63.29%

60.00% 25.00%

#50 24.78% 35.19%

30.00% 10.00%

#100 4.97% 4.97%

10.00% 2.00%

Pan 0.00% 0.00% 0.00% 0.00%

F.M. 2.71 2.44

a study on behavior and improvement of expansion of

Documents