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MA/41

CONCRETE TECHNOLOGY UNIT

Modern coal-fired power station ash products

Minutes of the Sixth Steering Committee Meeting, Wednesday 20 August 2014

Present: C Bennett, R Carroll, L J Csetenyi, M R Jones, M J McCarthy and H I Yakub

Actions

1. Welcome

MR Jones welcomed the members to the Sixth Steering Committee meeting.

2. Apologies

Apologies were received from R Boult (Cemex).

3. Minutes of the Fifth Steering Committee Meeting [MA/34]

The Minutes were accepted as a true record of the meeting.

4. Update on Actions Allocated at the Previous Meeting

MJ.McCarthy summarized the status of actions allocated at the previous meeting. It was

noted that two supercritical fly ashes (SCFA1 and SCFA2) have been received from

ECOBA. It had been hoped that a biomass-only fly ash could be included in the project,

but this has not been possible. Further information about the fly ashes in the study, in terms

of which has been air-classified, is still to be established. CTU, RC

The new stainless steel flow table (BS EN 1015-3) has now been motorised and is

operational. Tests using the fly ashes from the study will be carried out and results reported

from these in due course. CTU

Testing is on-going with Fly Ash LFA (produced using similar technology to SNCR),

which was received from C.Bennett towards the end of 2013. The suggested

characterization tests with this have been carried out and are reported under Item 6. Water-

saving concrete tests have also been carried out and are reported under Item 8.

It was noted that the CTU would be able to examine air void parameters using an automated

system and the concretes being tested would be investigated using this to contribute to the

understanding of the freeze/thaw results. CTU

5. Update on Materials for the Project [MA/36]

As noted in Item 4, samples SCFA1 and SCFA2 have been received for the project.

Unfortunately oxyfuel fly ash, which it was hoped would be obtained via ECOBA, is not

available. It was proposed that oxyfuel fly ash from a pilot-scale burner, available from another

project, would be included. No other materials have been obtained since the last meeting.

A discussion was held about other potential materials that might be considered for the project,

but recognising that it is in its final stages. It was suggested that Rugely beneficiated fly ash

should be included. R Carroll agreed to source of this. RC

MA/41

6. Material Characterization and BS EN 450-1 Test Results [MA/37]

It was noted that new information from the characterization work, obtained since the last

meeting, corresponded to LFA, and SCFA1 and SCFA2.

LFA had a moderate LOI and a relatively high BET surface area, although its foam index was

not that high. It appeared to contain agglomerates and a number of unburnt particles.

SCFA1 and SCFA2 had relatively low LOIs, BET surface areas and foam index values. The

majority of particles under the SEM appeared to be spherical.

Much of the material characterization work is now complete, with a few results to come for

activity index.

7. Update of Concrete Strength Results [MA/38]

The data from the concrete strength test results was presented, which have now reached

180 days for many of the fly ashes. There was some discussion about the behaviour of the

Portland cement (PC) used, gave continued strength gains with time in the reference

concrete (approx. 10 MPa at 0.55 w/c ratio between 28 and 180 days). It was felt that this

may be a factor in the fly ash concretes still indicating lower strength by 180 days.

There was a discussion about the water saving concretes and while they demonstrated that

water savings of between 10 and 15 l/m³ are possible, they also indicated lower strength

than the PC concrete to 180 days.

It was suggested that the properties of the PC being used in the study be compared with

those used in previous work to see if underlying effects can be identified. CTU

8. Update of Concrete Durability Results [MA/39]

The concrete durability results were presented. In most cases, these are now moving

towards the advanced stages of their testing. The following were noted.

Chloride testing was on-going and the main data for this property, using chloride profiles,

would be reported in due course. The NT Build test results suggest little effect of fly ash

characteristics on chloride ingress.

Carbonation results (both accelerated and normal exposure) suggest that the characteristics

of fly ash, with one or two exceptions, have little influence on the property.

The sulfate expansion tests indicate that there has been little change in length for the various

fly ash concretes considered for the test period to date. Noticeable expansions and damage

have been obtained for some of the PC reference concretes at high w/c ratio.

Some variations in freeze/thaw and abrasion have been noted between concretes. These

are being examined in more detail to identify whether they relate to the fly ash production

details. PC reference concretes appeared to perform best in these tests.

ASR tests are at their early stages and there is little sign of noticeable expansion or surface

damage to date.

9. Proposed Leaching Study

Details of the leaching study were reviewed. Two leach test methods have been considered,

relevant in the waste acceptance criteria. For fly ash: BS EN 12457-3 and for concrete:

NEN 7375.

The results from these tests will be compared with the limits set by the UK Environment

Agency to determine whether the test materials, in loose (fly ash) or bound (concrete) form,

are hazardous. Concrete leaching tests have been carried out and fly ash tests will be

completed shortly. The leachates from these tests will be analysed using voltammetry for

any harmful species identified from XRF. CTU

MA/41

10. Structure of the Final Report [MA/40]

The structure of the final report covered in MA/40 was considered. At this stage, it was

agreed that its contents were reasonable. It is anticipated that progress on this would be

made in the next 6 months.

11. Research Plan for the Next 6 Months

It was envisaged that testing would continue and be nearing completion. The analysis and

writing stages would be in progress over this period.

12. AOCB

There was no other business.

13. Date of the Next Meeting

The date of the next meeting is Thursday 12 February at 9.00 am, Room H20, Fulton

Building, University of Dundee.

LJC/MJMC

04 February 2015

MA/42

CONCRETE TECHNOLOGY UNIT

Modern Fly Ashes for Concrete Construction

Seventh Project Steering Committee Meeting, 12 February 2015

09.00 -11.00 Thursday 12 February 2015,

Meeting Room H20, Fulton Building, University of Dundee

AGENDA

1. Welcome

2. Apologies

3. Minutes of the Sixth Steering Committee Meeting [MA/41]

4. Update on Actions Allocated at the Previous Meeting

5. Update on Materials for the Project [MA/43]

6. Material Characterization and BS EN 450-1 Tests [MA/44]

7. Update of Concrete Strength Results [MA/45]

8. Update of Concrete Durability Results [MA/46]

9. Leaching Studies

10. Final Report

11. A.O.C.B.

LJC/MJMC

04 February 2015

MA/43

Modern Fly Ash for Concrete Construction

Update on Materials for the Project

MA/43 Page 2 of 2

Modern Fly Ashes for Concrete Construction — Materials for the Project

No. Ash

Ref. Description Source

Date

Sampled

Approx.

Quantity

Available

Status

1 HN1 Pre 1999 Ash Ratcliffe Pre-1999 25 kg Received

2 HN2 Stockpile Ash Ratcliffe Jun-02 100 kg Received

3 HN3 10% Petcoke ash Ratcliffe Mar-04 25 kg Received

4 PM1 German ash fitted with

SNCR

Herne PS,

Germany Sep-11 75 kg Received

5 LS1 UK ash Longannet Sep-04 25 kg Received

6 LS2 UK ash Cottam Oct-04 25 kg Received

8 RFA1 Pre-beneficiation fly ash Rugeley Nov-15 50 kg Received

9 RFA2 Post-beneficiation fly ash Rugeley Nov-15 50 kg Received

10 SCR2 Ash from station fitted

with SCR

Moneypoint

(Eire) Jan-12 50 kg Received

11 PRO1 Ash from wet processed

stockpile material

Fiddlers

Ferry Oct-11 100 kg Received

12 BL1 Ash from base load station West Burton Jan-12 100 kg Received

13 NH1

Ash from station fitted

with ammonium injection

prior to the precip

RWE -

Aberthaw Feb-12 100 kg Received

14 BL2

Ash from station fitted

with ammonium injection

prior to the precip

RWE -

Aberthaw Feb-12 100 kg Received

15 DFA BS EN 450 Type S Ash Drax Sep-12 100 kg Recieved

16 LFA From station that uses

similar tech to SNCR Longannet Sep-13 75 kg Recieved

17 SCFA1

Ash from a station that

uses super critical steam

generators.

ECOBA May-14 50kg Recieved

18 SCFA2

Ash from a station that

uses super critical steam

generators.

ECOBA May-14 50kg Recieved

MA/44


Material Characterization and BS EN 450-1 Test Results

Concrete Technology Unit

Division of Civil Engineering

University of Dundee

Dundee

DD1 4HN

MA/44 Page 2 of 31

1. Introduction

This document provides a summary of the results from characterisation tests carried out on the fly

ashes received for the project.

The properties described were determined using test methods given in British/European standards,

or following established techniques at the University of Dundee.

2. Test Materials Received

During the last 6 months (December 2014) fly ashes RFA1 and RFA2 from Rugeley power station

were received. The materials being considered for the modern fly ash project (noted in Document

MA/43) are given in Table 1.

3. Summary of Test Results

Tables 2, 3, 4 and 5 provide the data for physical and chemical properties of the above fly

ashes. The results of these are also given in Figures 1 to 13, with scanning electron microscopic

(SEM) images shown in Figures 14 to 29 .

3.1 Fineness

The results of the 45 µm sieve retention tests are given in Figure 1. These indicate that PRO1

(processed material) gave highest fineness, with only 2.6% retained on the 45m sieve, and as

with BL1, RFA1, RFA 2 and LS2, met the fineness requirement of Type S to BS EN 450-1.

HN1, LFA, DFA, HN3, SCR2, LS1, NH1, BL2, SCFA1, SCFA2 and PM1 were all relatively

coarser, but within the limit of Type N to BS EN 450-1. HN2 was from a stockpile and did

not achieve this. Visually, the presence of some agglomerates was also noted in this material.

As indicated by Figure 7, the PSD (d50) results for the fly ashes show general agreement with

the 45 m sieve retention data, with PRO1, RFA1, RFA2, BL1 finest and HN1, HN2, HN3

and BL2 at the coarser end.

The supercritical fly ashes (Figure 1 c) have sieve retentions in the range of 20 to 30%. Post-

combustion low NOx fly ashes (Figure 1 a) have fineness in the range of 12 to 23 %. Since

these are downstream of the boiler, it is anticipated that the fineness would be unaffected by

this technology.

MA/44 Page 3 of 31

The co-combustion fly ashes (Figure 1 b) tend to have relatively high sieve retentions, which

is similar to that found in other studies i.e. this may produce fly ash with larger particle sizes

due to lower burning temperatures and agglomeration of particles. However these materials

were still within the limits of Type N fly ash.

3.2 LOI, N2 Adsorption and Foam Index

The results obtained from the LOI tests are given in Figure 2. All of the fly ashes, except for

NH1, BL2, HN3, LFA and HN2 had LOI’s < 7.0% and, therefore, met the requirements of BS

EN 450-1. The fly ashes of higher LOI tended to be coarser and darker in colour, particularly

NH1. The (BET) N2 adsorption, shown in Tables 2 and 3 ranged from between 0.86-5.94 m2/g

with SCFA2 and LFA having the lowest and highest surface areas respectively. As shown in

Figure 8, these did not necessarily follow the LOI results.

The results shown in Figure 3 are foam index values, obtained using SDBS (0.01M) as the

surfactant and the automatic shaker described in an earlier study. Figure 9 shows the general

agreement between foam index and BET (N2) values. However, as noted with the BET (N2),

the foam index values did not follow the LOI results.

Post-combustion low NOx fly ashes, apart from LFA, have relatively low LOI, BET and foam

index values (< 3.5%, < 1.15 m2/g and < 80l respectively). This suggests that these fly ashes

would be suitable for air-entrainment. Similar behaviour was also observed for supercritical

fly ashes.

The co-combustion fly ashes, BL2 (woodchip), NH1 (woodchip) and HN3 (petcoke), have

relatively high LOI (10 to 18%), which may be due to incomplete combustion of the co-fuel

and lower flame temperatures. Petcoke has been shown to have low volatility, thereby giving

fly ash with higher LOI when used as a co-fuel. In the case of NH1 and BL2, this had an effect

on its foam index (320 and 300 l respectively), which may affect their suitability for air-

entrainment. However, different behaviour was observed from HN3 petcoke fly ash. It had a

low foam index despite its high LOI. This is in agreement with other studies which found that

petcoke carbons are dense and have low surface area, thereby adsorbing little AEA.

MA/44 Page 4 of 31

3.3 Water Requirement and Strength Factor

The water requirement results (using the BS 3892-1 flow table) are given in Figure 4. These

indicate that finer fly ashes generally gave lower water requirements, with values from 93-

98% of the reference PC mortar. However, in cases where the fineness (45µm sieve residue)

exceeded 20%, water requirements were greater than 100%, with a maximum value of 108%

noted for HN2 and NH1. The results indicate that while some of the fly ashes met Type S

requirements for fineness, they did not necessarily achieve the 95% limit for water requirement

(BS 3892-1/BS 4551-1).

A comparison of selective water requirement and strength factor results (BS 3892-1) is given

in Figure 11. These indicate general agreement between the properties, with reducing strength

factor noted at increasing water requirement. It is also evident from the results that the mortars

meeting the 0.85 value for strength factor at 28 days were mainly those with water

requirements less than 100%.

The co-combustion fly ashes (Figure 4 b) had a negative effect on the water requirement of

mortars (requiring 105-108% of the reference). This may be because co-combustion fly ashes

tend to exhibit agglomeration and have larger, less rounded particles which may have an effect

on the cohesiveness and water demand of these fly ashes. This may influence the use of these

materials in concrete, affecting workability.

The low NOx combustion fly ashes (Figure 4 a) and supercritical fly ashes (Figure 4 c) had

water requirements close to 95% suggesting they may have potential water saving properties.

3.4 Activity Index

The results from tests for activity index at 28 and 90 days are given in Figures 5 and 6. These

indicate that the fly ashes all met BS EN 450-1 activity index requirements at both test ages

(75% at 28 days and 85% at 90 days). By 90 days all of the fly ashes, except HN2 and HN3,

had activity index values higher than the reference PC. The results of HN2 may be influenced

by its storage conditions and agglomeration of particles, as noted previously.

The relationships obtained between fly ash fineness and activity index at the two test ages are

shown in Figure 12. The fly ashes exhibiting higher values were generally of greater fineness.

The improved relationship at 90 days also corresponds to the period where fly ash has greatest

MA/44 Page 5 of 31

reactivity. The red markers (Sample PRO1) were not included in the regression analysis,

because they represent processed fly ash, which although fine, did not follow the same trend

at 90 days.

Low NOx fly ashes (Figures 5 a and 6 a) supercritical and oxy-fuel fly ashes (Figures 5 c and

6 c) met the 28 and 90 day requirements of BS EN 450-1. Similarly, the reactivity of the co-

combustion fly ashes (Figures 5 b and 6 b) was largely unaffected, despite their high LOI.

3.5 Oxide Composition and Mineralogy

The bulk oxide composition and mineralogy of the fly ashes are given in Tables 4 and 5. These

indicate that all of the fly ashes were of low lime content (with CaO mainly less than 5%) with

all, except for SCFA1 and SCFA2, achieving the BS EN 450-1 requirement for the sum of the

main oxides (>70%). All of the fly ashes also met those for SO3 and alkali contents. However,

it is interesting to note the relatively high sulfur content of the HN3 (petcoke co-combustion

fly ash).

SCR2, LFA and LS1 contained significantly higher quartz (20.7%, 19% and 17.5%

respectively, range: 3.9-20.7%) than the other fly ash samples, furthermore LS1 had a higher

mullite content (26.0%, range: 7.6-26.0%) than the other materials. The ‘others’ content of

the fly ashes varied mainly between 68.6% and 85.1%, with LFA and BL2 fly ashes at the

lower and upper end of this range. LS1 had a noticeably lower value than the other materials

considered.

3.6 Colorimetry

The lightness values of the fly ashes are given in Tables 2 and 3 and are in the range of 52.8

to 63.4, with NH1 having the lowest and SCR2 the highest values. For reference, the lightness

of Portland cement was 65.5. Table 6 gives examples of colours in the measured range. The

results indicate that there was a relationship between lightness and LOI as shown in Figure 13.

This means that high LOI fly ashes (e.g. co-combustion fly ashes) may produce darker

concrete, potentially making the material unsuitable for projects where this is important.

MA/44 Page 6 of 31

3.7 Fly Ash Morphology

SEM images of the fly ashes are shown in Figures 14 to 28. From the images, Type S fly

ashes generally tended to be more rounded and uniform in appearance than those of Type N.

Similarly, the finer fly ashes with rounded particles tended to perform better in the activity

index tests.

The low NOx fly ashes (Figures 15, 19 and 23), apart from LFA, appeared to be free of carbon

and scoria. They contain, for the most part, smooth, spherical particles, with a good spread of

particle sizes. Similar features were also observed for the supercritical fly ashes (Figures 27

and 28). This shows agreement with the water saving, LOI and BET results for these materials.

LFA contained noticeably more carbon, which appeared to have partially melted surfaces. It

also contained more scoria and irregular particles. However, it is unlikely that these effects

have been caused by post-combustion NOx reduction.

In general, the co-combustion fly ashes (Figures 14, 24 and 26) appear to have remnants of

carbon and scoria present, which may be due to lower flame temperatures and incomplete

combustion of the co-fuel. This shows agreement with the high LOI and BET values observed

for these materials. They also appeared to have rougher surfaces, due to partial crystallisation

of the fly ash surfaces, and the presence of some irregular particles. Furthermore a number of

agglomerates were also observed. These effects may be caused by lower combustion

temperatures and a lack of alkali oxides.

MA/44 Page 7 of 31

3.8 Conclusions

The initial stages of the study have involved physical and chemical characterization of the fly

ashes. It appears, from the testing and literature, that co-combustion may cause the following,

1. Increase in LOI

2. Increased Foam Index

3. Increased coarseness

4. Increase in particle sizes

5. Slight variations in oxide composition and mineralogy

However, the results suggest that coal fired power plants operating post combustion measures

for NOx reduction or supercritical steam generation do not affect fly ash properties, possibly

because they do not influence boiler conditions.

The above effects may influence fly ash behaviour in cementitious systems and there is a need

to evaluate these, to ensure continued suitability of the material as a valuable construction

resource.

MA/44 Page 8 of 31

Table 1. Summary of fly ash test samples

Ash Code Source Date Received Quantity Production/Origin

PM1 Herne PS, Germany Sep-11 75 kg German fly ash

Fitted with SNCR

PRO1 SSE - Fiddlers Ferry Nov-11 100 kg Fly ash from wet processed

stockpile material

HN1 E.ON – Radcliffe

Power Station Nov-11 25 kg Pre 1999 fly ash


Power Station Nov-11 50 kg Stockpile fly ash


Power Station July-12 25 kg 10% Petcoke fly ash

LS1 Scotash - Longannet Jan-12 20 kg UK fly ash

LS2 EDF - Cottam Jan-12 20 kg UK fly ash

BL1 West Burton Jan-12 100 kg

Fly ash from station fitted with

Selective Catalytic Reduction

(SCR)

NH1 RWE - Aberthaw Feb-12 100 kg


ammonium injection prior to the

precipitators

SCR2 ESB – Moneypoint

(Eire) Feb-12 100 kg Fly ash from base load Station 1

BL2 RWE – Aberthaw Apr-12 100 kg


ammonium injection prior to the

precipitators

DFA Drax Sep-12 100 kg BS EN 450 Type S Ash

LFA Longannet Sep-13 75 kg From station that uses technique

similar to SNCR

SCFA1 ECOBA May-14 50 kg From a station that uses super

critical steam generators.

SCFA2 ECOBA May-14 50 kg From a station that uses super

critical steam generators.

OFA Drax Aug-10 25 kg Oxy-fuel ash from trial burner

RFA1 Rugeley Oct-14 50 kg Fly ash produced prior to

beneficiation

RFA2 Rugeley Oct-14 50 kg Fly ash produced after

beneficiation

MA/44 Page 9 of 31

Table 2. Physical properties modern and processed fly ashes

Properties PM1 NH1 SCR2 BL2 HN3 LFA SCFA1 SCFA2 OFA

Loss on Ignition, % 3.4 17.3 2.6 13.7 9.8 7.3 2.4 1.4 5.4

Moisture content, % 0.0 0.2 0.2 0.2 0.3 0.2 0.2 0.2 0.2

Water requirement, % 96 108 96 105 106 98 97 96 101

45 mm sieve residue, % 15.1 27.2 12.1 24.4 29.4 22.5 20.0 29.6 19.1

Nitrogen adsorption, m2/g 0.93 3.43 1.12 3.45 2.24 5.94 1.81 0.86 2.46

Foam index1, µl 40 280 60 260 100 140 100 20 220

Lightness value 60.6 52.8 63.4 53.4 53.6 57.1 63.3 60.1 -

28 Day activity Index, % 79 75 84 83 76 80 81 84 86


Strength factor 0.87 0.73 0.97 0.82 0.74 - - - -

PSD d(0.1), µm 2.5 3.4 2.1 2.6 3.1 2.0 3.6 3.8 7.9

PSD d(0.5), µm 19.1 33.1 14.8 29.7 34.0 24.0 46.1 30.8 30.3

PSD d(0.9), µm 77.4 117.6 78.8 94.0 125.7 109.4 231.8 122.7 81.8

1 AEA reagent used: 0.01 M SDBS (sodium salt of dodecyl benzene sulfonate)

MA/44 Page 10 of 31

Table 3. Physical properties of processed and ‘other’ fly ashes

Properties PRO1 LS1 LS2 HN1 HN2 BL1 DFA RFA1 RFA2

Loss on Ignition, % 4.8 4.6 4.8 5.9 8.3 4.4 4.0 3.1 2.4

Moisture content, % 0.4 0.2 0.4 0.6 0.5 0.3 0.3 0.12 0.07

Water requirement, % 94 104 98 102 108 95 93 98 97

45 mm sieve residue, % 2.6 20.5 11.0 32.8 49.5 9.6 13.2 11.6 8.7

Nitrogen adsorption, m2/g 4.25 2.91 1.25 1.81 5.40 1.74 2.29 2.86 2.51

Foam index1, µl 120 140 100 100 140 160 100 240 240

Lightness value 60.1 55.3 57.5 53.6 53.2 60.0 57.4 - -


90 Day activity Index, % 103 105 106 103 97 112 105 - -

Strength factor 0.89 0.83 0.93 0.86 0.77 0.97 0.82 - -

PSD d(0.1), µm 1.2 2.6 2.8 3.2 5.6 1.8 2.7 1.7 2.1

PSD d(0.5), µm 8.6 20.4 17.1 28.2 42.7 12.1 14.1 12.4 15.1

PSD d(0.9), µm 33.7 94.2 67.5 106.5 140.5 57.5 65.1 64.1 55.3

1 AEA reagent used: 0.01 M SDBS (sodium salt of dodecyl benzene sulfonate)

MA/44 Page 11 of 31

Table 4. Oxide and mineralogical compositions of modern fly ashes

Component, % PM1 NH1 SCR2 BL2 HN3 LFA SCFA1 SCFA2 OFA

CaO 3.74 2.94 1.91 3.55 4.63 1.64 4.47 4.19 4.2

SiO2 47.07 41.98 51.42 42.86 39.41 45.74 43.97 44.43 49.3

Al2O3 19.93 20.82 17.34 20.92 21.07 16.55 16.34 16.00 19.7

Fe2O3 9.13 8.15 8.96 6.71 12.99 7.72 7.89 8.49 13.4

MgO 1.66 1.17 1.60 1.09 1.40 1.09 1.38 1.37 1.1

MnO 0.09 0.09 0.06 0.12 0.13 0.04 0.05 0.05 0.1

TiO2 1.07 0.94 0.96 0.98 1.03 0.83 0.81 0.87 1.1

K2O 3.37 2.05 2.04 1.55 2.52 1.73 1.79 1.90 2.3

Na2O 1.44 0.75 1.74 0.84 1.19 1.24 1.69 2.88 0.8

P2O5 0.84 0.86 0.23 0.89 0.56 0.15 0.43 0.29 0.2

SO3 1.24 1.24 1.45 0.8 2.55 1.08 0.74 0.91 2.8

Quartz 11.1 4.8 20.7 3.9 7.0 19.0 5.6 10.7 12.8

Hematite 2.7 1.5 2.4 1.4 2.6 1.7 2.4 3.0 4.5

Magnetite 0.2 0.2 0.1 0.1 0.4 0.1 0.2 0.2 0.1

Mullite 8.8 11.8 7.6 9.5 11.9 10.6 5.6 6.2 17.9

Others 77.2 81.8 69.2 85.1 78.1 68.6 86.2 79.9 64.6

MA/44 Page 12 of 31

Table 5. Oxide and mineralogical compositions of processed and ‘other’ fly ashes

Component, % PRO1 LS1 LS2 HN1 HN2 BL1 DFA

CaO 2.74 3.41 5.26 4.03 2.67 3.01 2.31

SiO2 48.28 52.78 46.11 43.40 43.81 48.39 49.81

Al2O3 23.98 25.16 25.93 23.28 23.42 20.12 22.31

Fe2O3 7.64 4.33 6.21 11.01 10.97 8.35 7.94

MgO 1.70 1.24 1.91 1.81 1.77 1.60 1.49

MnO 0.06 0.05 0.08 0.08 0.08 0.06 0.05

TiO2 1.12 1.26 1.30 1.10 1.05 1.03 1.13

K2O 3.15 1.45 2.22 2.67 2.86 2.80 3.42

Na2O 0.74 0.81 1.51 1.71 0.90 2.01 1.33

P2O5 0.38 0.65 1.01 0.54 0.26 0.46 0.23

SO3 0.55 0.45 1.02 1.40 0.80 0.97 0.89

Quartz 7.1 17.5 8.0 8.6 6.8 9.8 11.1

Hematite 1.8 2.0 2.1 3.2 3.4 2.2 2.3

Magnetite 0.0 0.1 0.1 0.1 0.1 0.1 0.2

Mullite 16.9 26.0 19.6 15.6 13.3 10.4 11.0

Others 74.2 54.3 70.2 72.4 76.4 77.6 75.5

MA/44 Page 13 of 31

Table 6. Comparison of lightness values with fly ash colour

Sample Lightness Value Colour

SCR2 63.4

DFA 57.4

NH1 52.8

Portland Cement 65.5

MA/44 Page 14 of 31

(a) (b)

(c) (d)

Figure 1. Fineness (45 µm sieve residue) of fly ash samples

MA/44 Page 15 of 31

(a) (b)

(c) (d)

Figure 2. LOI of fly ash samples

MA/44 Page 16 of 31

(a) (b)

(c) (d)

Figure 3. Foam index of fly ash samples

MA/44 Page 17 of 31

(a) (b)

(c) (d)

Figure 4. Water requirement of fly ash samples

MA/44 Page 18 of 31

(a) (b)

(c) (d)

Figure 5. 28 day activity index of fly ash samples (in order of fineness)

MA/44 Page 19 of 31

(a) (b)

(c) (d)

Figure 6. 90 day activity index of fly ash samples

MA/44 Page 20 of 31

Figure 7

Figure 8 Relationship between specific surface area (by N2 adsorption) and LOI

MA/44 Page 21 of 31

Figure 9. Relationship between specific surface area (by N2 adsorption) and foam index

Figure 10. Relationship between LOI and foam index

MA/44 Page 22 of 31

Figure 11. Relationship between water requirement and strength factor

Figure 12. Relationship between fineness (45 µm sieve residue) and activity index

MA/44 Page 23 of 31

Figure 13. Relationship between LOI and fly ash lightness

MA/44 Page 24 of 31

Figure 14. SEM micrographs of NH1 Fly Ash

Figure 15. SEM micrographs of PM1 Fly Ash

MA/44 Page 25 of 31

Figure 16. SEM micrographs of HN1 Fly Ash


MA/44 Page 26 of 31

Figure 18. SEM micrographs of PRO1 Fly Ash

Figure 19. SEM micrographs of SCR2 Fly Ash

MA/44 Page 27 of 31

Figure 20. SEM micrographs of BL1 Fly Ash

Figure 21. SEM micrographs of LS1 Fly Ash

MA/44 Page 28 of 31

Figure 22. SEM micrographs of LS2 Fly Ash

Figure 23. SEM micrographs of LFA Fly Ash

MA/44 Page 29 of 31

Figure 24. SEM micrographs of BL2 Fly Ash

Figure 25. SEM micrographs of DFA Fly Ash

MA/44 Page 30 of 31


Figure 27. SEM micrographs of SCFA1 Fly Ash

MA/44 Page 31 of 31

Figure 28. SEM micrographs of SCFA2 Fly Ash

Figure 29. SEM micrographs of OFA Fly Ash

MA/45


Update of Concrete Strength Results




Dundee

DD1 4HN

MA/45 Page 2 of 27

1 Introduction

This document summarizes the results from the strength tests on the concretes outlined in

Document MA19 (Proposed Durability Study). The series of concretes in this document

are being considered for each fly ash in the study (except for LS1 and LS2, due to limited

material availability). Four w/c ratios covering the range 0.35-0.65, were considered with

a fly ash addition level of 30% and target slump class of S3. Compressive strength tests

were carried out up to 180 days for all w/c ratios and 365 days at 0.45 and 0.55. All fly ash

concrete samples, expect RFA1and RFA2, have been tested to the test ages indicated. The

fly ash sources and characteristics are given in Document MA44 (Material Characterisation

and BS EN 450-1 Test Results).

2 Materials and Mix proportions

The Portland cement used in the concretes was a CEM I, 52.5 N, while the aggregates were

a North Fife sand and gravel. The aggregate absorptions for sand, 4/10 and 10/20 aggregate

(from lab dry to SSD) were 0.8%, 1.4% and 1.3% and particle densities (at SSD)

2630 kg/m3, 2600 kg/m³, 2610 kg/m³. The superplasticizing admixture used was based on

a modified polycarboxylic ether. The fine to total aggregate ratios for the concrete mixes

were derived from the BRE mix design method. The mix proportions are given in Table 1.

Water saving mixes were considered using a selection of fly ashes, with compressive

strength tests up to 180 days carried out, following standard water curing. These fly ashes

were chosen because they required significantly lower admixture doses than the reference

concrete to achieve S3 slump. The admixture dose of the fly ash mixes was matched to the

reference concrete and the water was reduced as far as possible while still maintaining an

S3 slump. The water, for the reference, was fixed at 165 kg/m3 and a w/c ratio of 0.55 was

used. The fly ash level was kept at 30%.

The freeze-thaw mixes were air entrained, with a target air content of 5 (+1%, - 0.5%),

using an air entraining agent formulated for use with fly ash. The mix proportions for the

MA/45 Page 3 of 27

freeze-thaw concretes are given in Table 2. The water was kept at 165 kg/m3 and the fly

ash level was 30%. The w/c ratios used were 0.45 and 0.55 and the superplasticiser dose

was fixed at 3ml/kg of cement (or cement + addition).

3 Fresh properties

The plastic density measurements gave general agreement with the sum of the constituents

for the concrete mixes. The slump measurements were in the range of 105-155 mm, i.e.

within the limits of Slump Class S3. The superplasticizer (SP) doses required to achieve

Slump Class S3 were within the range of 0.3-0.9 % by mass of cement (recommended

limits for the admixture 0.25-1.0 %), as shown in Figure 1, with the SCR2 dose at the lower

end of this and NH1 the higher end. Except for HN2, HN3, LFA, SCFA1, SCFA2 and

NH1, all of the fly ashes gave reduced SP dose requirements compared to the PC reference

concretes.

Figure 2 shows the effect of fineness (45 m sieve retention) on these. The results indicate

that finer fly ash, with lower LOI generally required less SP to achieve the target slump

class. The SP dose also gave agreement with water requirement tests carried during

characterization, as shown in Figure 3.

The low NOx fly ashes, with the exception of LFA (dose range: 0.75 to 0.85 % cement

content), had SP doses in the range 0.30 to 0.55 % of the cement content. This is in

agreement with the fineness and water requirement results observed for these materials

from the characterisation. PM1 and SCR2 appear to have potential water saving properties.

The co-combustion fly ashes had relatively high superplasticiser dosages for all w/c ratios

(range: 0.55 to 0.9 % of cement content). Of these, BL2 and NH1 consistently had the

lowest and highest SP doses across all w/c ratios, with BL2 requiring marginally less than

the reference PC mix at 0.55 and 0.65 w/c ratios. Similarly, the supercritical and oxy-fuel

fly ashes had SP doses in the range of 0.55 to 0.8 % of the cement content (cf. PC, in the

range of 0.6-0.7 % cement content). The results suggest that these materials would not

provide any water saving benefits.

MA/45 Page 4 of 27

4 Compressive Strength

Compressive strength tests were carried out on 100 mm concrete cubes at test ages up to

180 days (following standard water curing). Strength tests up to 365 days were carried out

at 0.45 and 0.55 w/c ratios. The strength data are given in Figures 4 to 7 for the different

w/c ratios considered. These show that the fly ash mixes had lower strengths than those of

the PC references, but the differences tended to reduce with increasing test age, particularly

at low w/c ratio. In general, BL1 had the highest compressive strength over the range of

w/c ratios and test ages. HN2 tended to have the lowest compressive strength at all ages

and w/c ratios, which may be because it originates from a long-term stockpile, potentially

affecting its reactivity. Figure 10 gives the strength data up to 365 days at 0.45 and 0.55

w/c ratio. The results show that after 180 days, the strength gain in the PC concretes is

minor, whereas the fly ash concretes continue to gain strength (in the range of 10 to 20%).

After 365 days, PRO1 had the highest strength at both w/c ratios, and at 0.55 exceeded that

of the PC concrete. NH1 and BL2 had the lowest compressive strengths at 365 days for

0.45 and 0.55 w/c ratios respectively.

Figure 8 shows that the fineness of the fly ashes was closely related to the strength of

concrete at all ages and w/c ratios, with reductions noted with coarser fly ash. This is further

noted in Figure 9.

In general, there was little difference observed between the compressive strength of low

NOx fly ashes, however SCR2 and LFA consistently achieved the highest and lowest values

respectively. This shows agreement with activity index and fineness results for these fly

ashes. Similar trends were observed for co-combustion, supercritical and oxy-fuel fly

ashes, with little strength difference between them noted. This suggests that, although there

were variations in production, the resultant impact on concrete strength was minimal.

MA/45 Page 5 of 27

5 Water-Saving Compressive Strength Results

The fly ashes used and their corresponding water savings are shown in Figure 11. All fly

ashes concretes achieved a water reduction of 15 kg/m3, except for DFA, where this was

10 kg/m3. Strength results up to 180 days are shown in Figure 12. From this, it is apparent

that at all ages the water saving fly ash mixes had lower strengths than those of the PC

reference, with reducing differences at later test ages. PRO1 and BL1 had the highest

compressive strengths at 28 and 90 days respectively, while DFA was lowest due to its

higher w/c ratio. Figures 13 to 17 show the strength development of the water saving fly

ash concretes, compared with their non-water saving counterparts and Figure 18 shows the

strength increase associated with the water saving concretes. These indicate that all water

saving fly ash concretes had higher strengths than their equivalent non-water saving

concretes and were therefore closer to the strength of the reference PC concrete at all ages.

At 90 days, the water saving fly ash concretes, excluding DFA, achieved 88-91% of the

reference concrete strength (cf. 76-86% for non-water saving mixes). Similarly at 180 days

the fly ash concretes achieved 94-96% (cf. 77-87%) of the PC reference concrete strength.

6 Freeze-Thaw Compressive Strength Results

The freeze-thaw (FT) mixes were tested for compressive strength up to 90 days (following

standard water curing). The FT strength data is shown in Figures 19 and 20. As with non-

air entrained concrete, the air entrained fly ash concretes at a given w/c ratio had lower

strengths than the PC (REF). The 28 day strength of the fly ash concretes at 0.45 w/c ratio

varied between 26.5 and 34.0 MPa with LFA and DFA being at the lower and upper end

of this range respectively. At 0.55 w/c ratio, BL2 had lowest 28 day compressive strength

DFA highest, with values of 15.5 and 20.0 MPa respectively. Figure 21 shows a

comparison between air entrained and non-air entrained concrete. The air entrained

concretes at 0.45 w/c ratio typically had strengths 24-36% lower than the non-air entrained

concrete at 28 days (This corresponds to about 5% reduction per 1% air entrained), whereas

at 0.55 w/c ratio the air entrained concretes had strengths 37-48% lower than the

corresponding non-air entrained concretes at this age.

MA/45 Page 6 of 27

7 Comparison with 1990s Test Data

Fly ashes to BS EN 450, covering various UK sources and a range of properties, from an

investigation carried out at the CTU during the 1990s were also considered, where possible,

to provide older materials as part of the evaluation.

A comparison of compressive strength with respect to fly ash fineness is shown in Figure

22, while the range of strengths for the fly ashes to 28 days is given in Figure 23. The

results of the fly ash concretes from the 1990s study (w/c ratio 0.5, with similar aggregates,

slump class S2, without SP admixture) are also shown.

The results show that 28 day strength increases with fineness (range 2.6 to 49.5 %). A

similar trend is observed with the 1990s fly ashes covering a similar range of fineness (2.8

to 41.5 %). The results at 28 days show that there were differences between the fly ash

concretes of up to 5 MPa (range 34 to 39 MPa). As before, similar effects were noted in

the data from the 1990s with regard to the range of strengths (range 31 to 36 MPa). The

difference in absolute strength values may be due to material variations (e.g. aggregate and

cement). These results suggest that the modern fly ashes tend to follow established

behaviour.

MA/45 Page 7 of 27

Table 1. Concrete mix proportions

MIX Water/Cement

Ratio

CONCRETE MIX PROPORTIONS1, kg/m³

Free water Cement / Addition Aggregate

Total2

PC Fly ash Total Sand 10 mm 20 mm Total

PC reference

Mixes

1 0.65 165 255 0 255 910 375 695 1975 2395

2 0.55 165 300 0 300 850 380 705 1935 2400

3 0.45 165 365 0 365 790 380 710 1880 2410

4 0.35 165 470 0 470 720 375 700 1795 2430

Fly Ash

Mixes

1 0.65 165 180 75 255 895 370 685 1945 2365

2 0.55 165 210 90 300 845 375 695 1915 2380

3 0.45 165 255 110 365 775 375 695 1850 2380

4 0.35 165 330 140 470 700 365 680 1745 2380

1 Superplasticizer used in quantities necessary to achieve Slump Class S3

2 Typical measured plastic densities for the fly ash mixes was in the range of 2370-2395 kg/m3 and 2415-2420 kg/m3 for the PC mixes.

MA/45 Page 8 of 27

Table 2. FT Concrete mix proportions

1 Superplasticizer dosage was fixed at 0.3% by mass of the cement+addition (Glenium 51)

MIX Water/Cement

Ratio



Total


PC reference

Mixes

1 0.55 165 300 0 300 790 365 680 1840 2305

2 0.45 165 365 0 365 730 370 685 1785 2315

Fly Ash

Mixes

1 0.55 165 210 90 300 780 360 670 1810 2275

2 0.45 165 255 110 365 715 360 670 1745 2275

MA/45 Page 9 of 27

(a) (b)

(c) (d)

Figure 1. Superplasticiser dosages for concrete mixes

MA/45 Page 10 of 27

(a) (b)

(c) (d)

Figure 2 Relationship between superplasticiser dosage and fineness (45m sieve retention)

MA/45 Page 11 of 27

(a) (b)

(c) (d)

Figure 3 Relationship between superplasticiser dosage and water requirement

MA/45 Page 12 of 27

(a) (b)

(c) (d)

Figure 4. Compressive strength results at 0.35 w/c ratio

MA/45 Page 13 of 27

(a) (b)

(c) (d)


MA/45 Page 14 of 27

(a) (b)

(c) (d)


MA/45 Page 15 of 27

(a) (b)

(c) (d)


MA/45 Page 16 of 27

(a) (b)

(c) (d)

Figure 8. Relationship between compressive strength and fineness (45m sieve retention)

MA/45 Page 17 of 27

(a)

(b)

Figure 9. Relationship between fineness (45 m sieve retention) and

compressive strength

MA/45 Page 18 of 27

Figure 10. Strength results up to 365 days at 0.45 and 0.55 w/c ratios

(a)

(b)

MA/45 Page 19 of 27

Figure 11. Water saving per m3 of fly ash concretes

Figure 12. Compressive strength results for water saving fly ash mixes

MA/45 Page 20 of 27

Figure 13. Strength development comparison of SCR2 and SCR2 water saving concretes

Figure 14. Strength development comparison of PM1 and PM1 water saving concretes

MA/45 Page 21 of 27

Figure 15. Strength development comparison of DFA and DFA water saving concretes

Figure 16. Strength development comparison of BL1 and BL1 water saving concretes

MA/45 Page 22 of 27

Figure 17. Strength development comparison of PRO1 and PRO1 water saving concretes

MA/45 Page 23 of 27

(a) (b)

(c) (d)

Figure 18. Compressive strength results for water saving fly ash concretes

MA/45 Page 24 of 27

(a)

(b)

Figure 19. Freeze-thaw compressive strength results at 0.45 w/c ratio (air-entrained)

MA/45 Page 25 of 27

(a)

(b)

Figure 20. Freeze-thaw compressive strength results at 0.55 w/c ratio (air-entrained)

MA/45 Page 26 of 27

(a)

(b)

Figure 21. Comparison between 28 day strength results for air entrained and non-air

entrained concretes

MA/45 Page 27 of 27

Figure 22 Relationship between fly ash fineness and concrete strength

Figure 23 Strength development ranges up to 28 days

MA/46


Update of Concrete Durability Results




Dundee

DD1 4HN

MA/46 Page 2 of 28

1 Introduction

This document describes results obtained from the durability tests outlined in Document

MA/19 (Proposed Durability Study). Comparisons in this document are made at equal w/c ratio

and in some cases equal strength. To date, chloride migration, carbonation, sulfate attack,

abrasion, freeze-thaw and alkali aggregate reaction (AAR) tests have been carried out on

selected materials at a range of w/c ratios. The concretes used, described in MA/46 (Update of

Concrete Strength Results; see Tables 1, 2 and 3), have a fly ash level in cement of 30%, a

target slump class of S3 and were water and/or air-cured according to that required by the test

method.

2 Chloride Migration

This test was carried out according to the Nordtest method (NT Build 492) and gives a

measure of the resistance of concrete to chloride penetration. Initial tests considered four

fly ash samples at 0.35 w/c ratio and seven at 0.55 w/c ratio. The results from these are

given in Figure 1. At 0.35 w/c ratio, fly ash BL1 concrete had the lowest migration value

(12.9 × 10-12 m²/s), while that of PRO1 the highest value (15.5 × 10-12 m²/s). At 0.55 w/c

ratio, DFA concrete had the lowest value (20.0 × 10-12 m²/s) and, as before, that of PRO1

the highest (24.4 × 10-12 m²/s).

Figure 2 compares fly ash fineness (45 m sieve retention) and chloride migration data.

There appeared to be only small differences between fly ash concretes with respect to

fineness. Fly ash PRO1 was not included in the comparison, as it was wet processed and

appeared to behave differently to the other fly ash concretes. The findings are similar to

those from two compartment chloride diffusion tests carried out in the 1990s study looking

at a range of fly ashes, using equal strength concrete. This also supports other work, which

suggests that the quantity of fly ash in cement, rather than its properties, is the important

factor influencing chloride transportation.

Further chloride testing on concretes at 0.35, 0.45 and 0.55 w/c ratios has been carried out

according to BS EN 14629. This is a uni-directional chloride diffusion test and involves

immersing concrete in 30.0 g/l sodium chloride solution for 90 days and determining the

MA/46 Page 3 of 28

diffusion coefficient from chloride profiles obtained by grinding layers from the concrete

surface. Some of the results from this will be considered during the meeting.

3 Carbonation

The non-accelerated carbonation and accelerated carbonation tests follow CEN 12390-10

and BS 1881-131 methods respectively. The depth of carbonation was determined by

spraying the cross section of fractured concrete surfaces with thymolphthalein indicator

solution, and measuring the colourless region. To date, carbonation testing has been carried

out on 0.65, 0.55 and 0.45 w/c ratio concretes up to 360 days, with the results shown in

Figures 3 to 5. Further testing is planned at 540 days in March.

Accelerated carbonation results have been obtained for 0.45 and 0.55 w/c ratio concretes

at test ages up to 140 days. The carbonation rates for the concretes at 0.45 and 0.55 w/c

ratio are given in Figures 6 and 7 respectively. The general behaviour observed was similar

to that normally found for carbonation, i.e. increasing carbonation depth in concrete with

time, but at a reducing rate. After 140 days of exposure for 0.45 w/c ratio concretes, HN3

had the highest carbonation depth (5.2 mm) and BL2 the lowest (3.9 mm). For 0.55 w/c

ratio concretes, at 140 days, LFA (6.9 mm) and HN2 (8.2 mm) had the lowest and highest

carbonation depths respectively.

In general, all fly ash concretes performed similarly, with only slight variations noted

between materials. It appears that the modern fly ashes did not affect this aspect of

concrete. The Portland Cement (PC) reference concrete performed better than the fly ash

concretes at all test exposure ages during accelerated and non-accelerated tests. However,

as shown in Figure 8, when considering accelerated carbonation for a concrete meeting the

requirements of the standard, (BS8500-1, minimum grade 35N/mm2, max w/c ratio 0.6 and

minimum cement 280 kg/m3) the fly ash concretes performed similarly to the reference

concrete (6.6 mm), with LFA and SCR2 having the lowest carbonation depth at 6.2 mm

and HN2 and HN3 highest at 6.8 mm. Previous results from the 1990s study considering

MA/46 Page 4 of 28

this property for a range of fly ashes, with different characteristics in equal strength

concrete, gave general agreement with the data

4 Sulfate Attack

The sulfate exposure tests were carried out according to CEN 15697-2008. This was

determined by measuring the length and weight change of concrete samples exposed to

68.0 g/l sodium sulfate solution (46.0 g/l of sulfate). Sulfate tests have been initiated for all

fly ash samples, with results obtained up to 420 days for all w/c ratios. Due to the nature

of the sulfate attack test, it tends to take some time before results indicative of damage are

available. The expansion curves of Type S and Type N fly ash concretes and their

corresponding mass changes at 0.35, 0.45 and 0.55 w/c ratios are shown in Figures 9 to 11

respectively.

The results show that the fly ash concretes are performing similarly to the reference

concrete or better. Furthermore there seems to be little variation between the fly ash

concretes at this stage of the test. As before, it appears that the sulfate resistance of the fly

ashes is unaffected by the technology associated with their production. Visually there were

no signs of deterioration in the fly ash test concretes, however, the reference concrete gave

surface discoloration and minor deterioration at edges and corners (see Figure 12). The PC

reference samples at 0.55 w/c ratio are breaking apart, resulting in significant mass change

and expansion as noted in Figure 11.

5 Abrasion

The abrasion testing was performed according to the Modified BCA Method developed at

the CTU. The depth of tread recorded after 15 minutes of rolling and impacting action on

the surface of the concrete slab by the steel wheels is taken as the depth of abrasion (average

of 10 points). Abrasion tests have been carried out for all fly ashes at 0.45 and 0.55 w/c

ratios. The results for these are shown in Figure 13. At 0.45, BL1 had the highest abrasion

and DFA lowest in the range of 0.47 – 0.81 mm. For 0.55 fly ash concretes, the abrasion

depths ranged from between 0.67 - 1.10 mm, with SCR2 at the lower end and BL2 at the

upper end.

MA/46 Page 5 of 28

Figure 15 shows the variation in abrasion depth across the two w/c ratios tested. The area

shaded in grey represents the range of fly ash abrasion depths and the blue line the abrasion

depths for the Reference PC concrete. As shown in Figure 14, when considering a concrete

that meets the requirements (BS8500-1) for abrasion (minimum grade C40, minimum

cement content 325 kg/m3) DFA performed best, with an abrasion depth 0.63 mm (PC

reference: 0.55 mm), while BL1 performed worst with an abrasion of 0.88 mm.

6 Freeze-Thaw Scaling

The freeze-thaw tests were carried out according to CEN/TS 12390-9 and involve

measuring the amount (mass) of scaled material at regular intervals following exposure to

± 20ºC over 24 hours (with salt water as the freezing medium) for 56 cycles.

Figure 16 shows the air content and air entrainment dosage of each concrete mix. The air

entraining agent used for all concrete mixes was formulated for use with fly ash. All fly

ash concretes had air contents in the range of 4.8-6% and required air entrainment dosages

of between 2.7 – 5.5 (ml/kg of cement + addition) for 0.45 w/c ratio concretes and 4.3 –

11.0 (ml/kg of cement + addition) for those of 0.55. PRO1 is at the lower end for both w/c

ratios and NH1 at the upper end of the dosage range for 0.45 w/c ratio concretes, while

BL2 and LFA are at the upper end for those of 0.55. Figure 17 indicates that, as noted in

previous studies, there was a good correlation between fly ash specific surface area and

admixture dose to achieve the target air content.

The results show that the co-combustion fly ashes (BL2 and NH1) and LFA had the highest

AEA dosages. This is in agreement with the high LOI, BET and foam index values

observed for these materials.

The freeze-thaw results are shown in Figures 18 and 19 for concretes of 0.45 and 0.55 w/c

ratios respectively. At 0.45, LFA gave the least scaled material at 0.22 kg/m3 while NH1

the most at 0.87 kg/m3, whereas, at 0.55, BL2 had the least with 0.8 kg/m3 and DFA the

MA/46 Page 6 of 28

most with 1.64 kg/m3. The results also show that the PC reference concrete gave the lowest

scaling of the concretes tested.

7 Alkali Aggregate Reaction Results

AAR tests were carried out according to BS812-123:1999 and involve measuring the

expansion of concrete prisms at regular intervals, while being stored at high temperature

(38ºC) / humidity conditions for 1 year. So far, testing up to 39 weeks has been carried out

for 9 fly ash samples.

Figure 20 shows the expansion results for the AAR concretes. All of the fly ash concretes

have lower expansions than the PC reference. The level of expansion observed at this stage

of the test is small and therefore there is little difference between the fly ashes. In addition,

visually and reflecting the levels of expansions obtained, there were no signs of cracking

or deterioration in any of the concretes.

ASR mortar results are given in Figure 21 and show similar trends to those observed for

the concrete mixes. Little expansion has occurred, with only slight differences between the

fly different fly ashes, which were lower than the PC references for both aggregates. In

general, it appears that for concrete and mortar the method of fly ash production has not

had an effect on its AAR performance.

MA/46 Page 7 of 28

Table 1. Concrete mix proportions

MIX Water/Cement

Ratio



Total PC Fly ash Total Sand 10 mm 20 mm Total

PC control

Mixes

1 0.65 165 255 0 255 910 375 695 1975 2395

2 0.55 165 300 0 300 850 380 705 1935 2400

3 0.45 165 365 0 365 790 380 710 1880 2410

4 0.35 165 470 0 470 720 375 700 1795 2430

Fly Ash

Mixes

1 0.65 165 180 75 255 895 370 685 1945 2365

2 0.55 165 210 90 300 845 375 695 1915 2380

3 0.45 165 255 110 365 775 375 695 1850 2380

4 0.35 165 330 140 470 700 365 680 1745 2380

1 Superplasticizer used in quantities necessary to achieve Slump Class S3

MA/46 Page 8 of 28

Table 2. AAR mix proportions

MIX

CONCRETE MIX PROPORTIONSa, kg/m3

Free waterc Cement / Addition Aggregateb

Total Cem Fly ashd Total K2SO4 Sand 10 mm 20 mm Total

Reference 228 699 0 699 7.5 413 415 590 1417 2345

Fly ash 228 447 192 639 10.2 413 415 590 1417 2284

Table 3. FT Concrete mix proportions

MIX Water/Cement

Ratio



Total


PC reference

Mixes

1 0.55 165 300 0 300 790 365 680 1840 2305

2 0.45 165 365 0 365 730 370 685 1785 2315

Fly Ash Mixes

1 0.55 165 210 90 300 780 360 670 1810 2275

2 0.45 165 255 110 365 715 360 670 1745 2275

MA/46 Page 9 of 28

(a)

(b)

Figure 1. Chloride migration results for selected concretes

MA/46 Page 10 of 28

Figure 2

chloride migration results

Figure 3. Carbonation results for concretes at 0.65 w/c ratio

MA/46 Page 11 of 28

(a)

(b)


MA/46 Page 12 of 28

(a)

(b)


MA/46 Page 13 of 28

(a)

(b)

Figure 6. Accelerated carbonation results for concretes at 0.45 w/c ratio

MA/46 Page 14 of 28

(a)

(b)

Figure 7. Accelerated carbonation results for concretes at 0.55 w/c ratio

MA/46 Page 15 of 28

(a)

(b)

Figure 8. Accelerated carbonation results for concretes at equal strength (35 N/mm2)

MA/46 Page 16 of 28

(a) (b)

(c) (d)

Figure 9. Sulfate expansion curves of 0.35 w/c ratio concretes with their corresponding mass changes

MA/46 Page 17 of 28

(a) (b)

(c) (d)


MA/46 Page 18 of 28

(a) (b)

(c) (d)


MA/46 Page 19 of 28

Figure 12. The deterioration of PC reference samples due to sulfate attack

MA/46 Page 20 of 28

(a)

(b)

Figure 13. Abrasion results for concretes at 0.45 and 0.55 w/c ratios

MA/46 Page 21 of 28

(a)

(b)

Figure 14. Abrasion results for concretes at equal strength (40N/mm2)

MA/46 Page 22 of 28

Figure 15. Relationship between w/c ratio and abrasion depth

MA/46 Page 23 of 28

(a)

(b)

Figure 16. AEA dosages and air contents for freeze-thaw concretes

MA/46 Page 24 of 28

(a)

(b)

Figure 17. Relationship between BET specific surface area and AEA dosageNote: Air

entraining agent used was BASF Micro Air 115

MA/46 Page 25 of 28

(a)

(b)

Figure 18. Mass of scaled material for freeze-thaw concretes at 0.45 w/c ratio

MA/46 Page 26 of 28

(a)

(b)

Figure 19. Mass of scaled material for freeze-thaw concretes at 0.55 w/c ratio

MA/46 Page 27 of 28

(a)

(b)

Figure 20. ASR Expansion curves of concretes

MA/46 Page 28 of 28

(a)

(b)

Figure 21. ASR Expansion curves of mortars

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