3D Volume Analysis of Influence of SAP Contents and Curing Age on Air Void Distribution in High

7/21/2019 3D Volume Analysis of Influence of SAP Contents and Curing Age on Air Void Distribution in High

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3D Volume Analysis of Inuence of SAP Content andCuring Age on Air Void Distribution of High

Performance Concrete

Babatunde J. Olawuyi* and William P. Boshoff*

* Department of Civil Engineering, Stellenbosch University, Private Bag X1, Matielan !"##,

Stellenbosch, $estern Cape, So%th &frica

e'mail( babs)amess%n+ac+a

Abstract: The use of superabsorbent polymers (SAP) is one internal curing method being adopted for

the mitigation of autogenous shrinkage in concrete especially high strength/performance concrete(HSC/HPC) SAP absorbs !ater and releases the !ater internally !hen cement hydrates "t ho!e#er

lea#es micro #oids in this process and this can negati#ely influence the mechanical properties of

concrete This paper reports on three dimensional ($%) #olume analysis of the influence of SAP

content and curing age on air #oids distribution in HPC &our HPC mi'tures !ith different binder

constituents and !ater/binder (/) ratios +,and +,%(-.) +.(-.0) and +$(-$) !ere tested !ith

t!o grain si1es of SAP ( -## .m /ith pro%ct label 02SE3 CS 4! an "## .m, labelle 02SE3

CC 4!) The SAP contents !ere also #aried (-23 -.23 -$23 and -42) by !eight of binder

Concrete cylinders (0- mm in diameter and ,-- mm high) !ere cast and cured in !ater for different

ages (.5 06 and 7- days) before the dry hardened HPC !as sub8ected to 9:ray computed

tomography (CT) scanning for determination of the air #oid distribution The $% 9:ray images !ere

then e'amined and analysed using A#i1o &ire image analysis soft!are ; #ersion 5- to filter and

classify the indi#idual #oids for determination of the si1es distribution and #olume analysis of #oid

created by SAP in the HPC !ith the respecti#e influence of binder type !ater/binder ratio and curing

age assessed The CT scanning !as also used to affirm the grain si1es and distribution of the dry

SAP particles

Keywords: Computed tomography (CT) scanning $% : #oid analysis high : performance concrete

air #oid distribution superabsorbent polymers (SAP) SAP content binder type curing age


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1 INTRODUCTION

Concrete is a #ersatile material for construction !orks but it ho!e#er re for better output The concrete samples used for the image analysis !ere also made to appropriate


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si1es to gi#es a true reflection of the actual pore and #oid states "t further e'amines the influence of

hydration period SAP type SAP content and binder type on the air #oid si1e sphericity and

distribution

2 EXPERIMENTAL INVETI!ATION

2"1 Mater#a$s

T!o si1es of SAP ( -## .m /ith pro%ct label 02SE3 CS 4! an "## .m labelled 02SE3 CC

4!) !ere used at different SAP content -2 -.2 -$2 and -42 by !eight of binder The SAP are

thermoset polymers specifically co#alently cross:linked polymers of acrylic acid and accrylamide

neutralised by alkali hydro'ide !hich according to Schrofl +echtcherine Dorges =,4> ha#e been

pro#en efficient as internal curing agents in concrete The absorption capacity of the SAP is sho!n in

pre#ious !ork =,0> to be .0- g/g in distilled !ater and .0 g/g (ie .0-- 2) in cement pore solution

(CPS) for both SAP grain si1es

A natural sand !ith minimum particle si1e of $-- Em (ie all the particles smaller than $-- Em !as

remo#ed using the sie#ing method) ha#ing the follo!ing physical property &ineness +odulus (&+ F

.B7) coefficient of uniformity (Cu F .4$) coefficient of gradation (Cc F ,-.) and dust content (-$2)

of medium sand classification =,6> as obser#ed in the preliminary sie#e analysis reported in Gla!uyi

oshoff =,B> !as used as fine aggregate ,$ mm crushed grey!acke stone !as used as the coarse

aggregate GPC C+ " 0.0 I conforming to S I ,7B =,5> !as the binder !ith silica fume core'

slag and fly ash added as cement e'tender !hile Premia $,- (a PC) supplied by Chryso !as added

as superplastici1er The composition of the reference HPC mi'tures is sho!n in Table ,

Tab$e 1 +i' constituents of HPC mi'tures

Constituents

Jeference +i'es (kg/m$)

+,+,%

+. +$

ater ,.0 ,.0 ,$4 ,00

Cement (C+ " 0.0 I) 0$- 0$- 04- 0--

Coarse Aggregate (,$ mm ma'imum) ,-0- ,-0- ,-0- ,-0-

Sand (Jetained on $-- Em sie#e) 07- 07- B,- B--

&ly Ash ,..0 - - -

Core' Slag - ,..0 - -

Silica &ume 0.0 0.0 4- 4-

Super:plastici1er (Chryso Premia $,-) ., ., ,6 04

ater/binder ratio -. -. -.0 -$

2"2 Met%ods

&our reference HPC mi'tures of different binder combination types (cement silica fume fly ash and

core' slag)3 / (+, +,% (-.)3 +.(-.0) and +$(-$)) and .5:day characteristic strength (fck cube)

of B- +Pa minimum (ie C6-/CB0 ; C7-/C,-0 HSC) !ere made using the method described in AKtcin=,7> for HPC !ith other mi'es ha#ing #aried SAP contents (-.2 3 -$2 and -42) for the t!o SAP


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si1es (Sp,and Sp.) orkability and cohesion of the fresh HPC mi'tures !as determined using the

Slump flo! table to ensure consistent !orkability for all the mi'ture irrespecti#e of SAP content The

concrete !as cast in 0- mm ' ,-- mm cylindrical moulds and cured in !ater at .$ L $ oC for

different hydration periods (ie .5 06 and 7- days respecti#ely) in accordance to rele#ant S

Standards ; =. .- ., .. .$> The hardened HPC specimens !ere then placed in the o#en at 4-o

Cfor $- minutes after remo#al from curing tank at respecti#e hydration period to make it totally dry

before taken to the CT scanner for analysis +i' +, and +,%are both of the same / (-.)3 mi'ture

+, contains fly ash !hereas +,%has core' slag as cement e'tender The dry hardened HPC !as

sub8ected to 9:ray CT scanning for the determination of the air #oid distribution The $% 9:ray images

!ere then e'amined and analysed using A#i1o &ire #ersion 5- =.4> and MD Studio +a' .. =.0> (both

being commercial computer programmes) to filter and classify the indi#idual #oids for determination of

the si1es distribution and #olume analysis of #oid created by SAP in the HPC !ith the respecti#e

influence of binder type !ater/binder ratio SAP content and curing age The CT scanning !as also

used to affirm the grain si1es and distribution of the dry SAP particles

The $% 9:ray images !ere obtained using a Deneral lectric Phoeni' MTome9 .4- 9:ray micro

computed tomography scanner (micro:CT) ach concrete specimen !as mounted in a less dense

cardboard tube to reduce e'ternal influences on the samples during the scan Jeconstruction !as

performed !ith system supplied %atos Jeconstruction soft!are and analysis !as conducted The

#o'el si1e !as set to ,-- Em !ith settings at ,B- kM and ,0- EA for ':ray generation and image

ac


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The outcome of the analysis !as then plotted using histogram chart for the respecti#e HPC mi'tures

tested after .5 days of curing and is sho!n in &igure 6 to 7

a CT scan of HPC cylinder !ith $% #isuali1ation of porosity in blue b Thresholding applied to sliced .% image

'(re 1,-- Em scan of concrete cylinder !ith $% #isuali1ation of porosity in blue

%etermination of the dry SAP particle si1e distribution !as carried out by scanning the t!o SAP types

separately in a transparent cylindrical container Jeconstruction !as performed as e'plained abo#e

!ith system supplied %atos Jeconstruction soft!are and analysis conducted !ith the A#i1o &ire 5-

follo!ing the steps stated pre#iously The scanning !as ho!e#er done at . Em #o'el si1e to be able

to capture the actual si1e of the SAP particles !hile a crop of 5- mm ' 4- mm ' 4- mm !as made

centrally from the MD" file !hen loaded before thresholding The analysis ho!e#er e'amined a

complete particle distribution of the dry SAP samples rather than indi#idual particle e'amination as

earlier reported =$-> &igure .a sho!s a $% image of separated SAP particles !ith different colours

depicting #arious si1e categories !hile &igure .b gi#es the .% image of centrally cropped dry SAP

specimen being analysed !ith the separated SAP particles in blue colour !ith spaces in bet!een

them

(a) (b)

'(re 2 $% "mage of separated dry SAP particles !ith colour indicating si1es classification (a) and(b) Centrally cropped CT image of dry SAP particles obtained from $% MD" file


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) REULT AND DICUION

)"1 AP #*es a+d ,or-%o$o'y

The SAP particles !ere obser#ed to be of #aried si1es and shapes3 they are mostly angular and

irregular in shape and not totally spherical The grain si1es are noted to be in the range of-/$-- Em (Sp,) and -/0-- Em (Sp.) !hen e'amined under CT scanning ($%) image analysis (&igure

.) These #alues agree #ery !ell !ith the manufacturer?s specification of

$-- Em (Sp,) and

6-- Em (Sp.) respecti#ely Table . sho!s the fre This ga#e a clearer detailed and more reliable assessment than the

approach adopted in an earlier study =$-> !hich in#ol#ed only random e'amination of indi#idual SAP

particle !ith a resultant si1e range of B0 Em to $0- Em (dry SAP) and ..0 Em to ,-0- Em (s!ollen

SAP)


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Tab$e 2&re


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'(re ): 2 cumulati#e #olume present of #arious particle si1es for Sp,and Sp.

'(re /:CT image of e'amination of indi#idual SAP particles obtained from a $% MD" file


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)"2 )D 0o#d A+a$ys#s o PC s-ec#,e+s

&igure 6 to 7 for the #arious HPC mi'tures after .5 days of hydration re#eals that air #oids e'ists in all

the HPC samples irrespecti#e of the SAP content and concrete mi'ture The peak of the histogram

!ere noted to be around the same #alues (ie ..0 Em ; $-- Em diameter air #oids F --6 ; -,4,

mm$pore #olume si1es) !hereas only a reference mi' + ,%has a peak at $B0 Em These can be seen

to refer to air #oids created by SAP dry particles of si1es - to ,-- Em3 the range !ithin !hich bulk of

the particle si1es of SAP belong as seen in Table . A critical study of histograms further re#eals that

the air #oids distribution are more and of !ider spread in HPC specimen containing SAP Presence of

micro:air #oids in the reference mi'es also sho! that the high concentration of superplastici1er

resulted in air bubbles !hich could not be totally eliminated by #ibration of concrete SAP addition

ho!e#er created more air #oids in the HPC and these air #oids !ere obser#ed to be !ell distributed

!ithin the concrete

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'(re 3:Histogram Plot of Air Moid %istribution of (.0 ' .0 ' 0- mm $) +,; HPC Samples

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'(re 4:Histogram Plot of Air Moid %istribution of (.0 ' .0 ' 0- mm $) +,%; HPC Samples

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'(re 5:Histogram Plot of Air Moid %istribution of (.0 ' .0 ' 0- mm $) +.; HPC Samples

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'(re 6:Histogram Plot of Air Moid %istribution of (.0 ' .0 ' 0- mm $) +$; HPC Samples)") I+$(e+ce o AP co+te+ts o+ A#r Vo#d D#str#b(t#o+

The general trend is that SAP #oid 2 and total #oid 2 (ie percentage porosity) increased as the SAP

content increased and also as / increased !ith little #ariations (&igures 0 to 5) &igure 7 sho!s that

the SAP #oid 2 increased !ith increase in SAP contents for all HPC mi'tures at .5 days irrespecti#e

of the SAP si1e e'cept for the outliers The higher the binder (ie fines) content the lo!er the porosity

and hence the better the HPC produced The reason for the obser#ed #ariation could be due to the

fact that only single sample of each specimen !as used for the CT scanning analysis further !orks

using triplicate samples is thereby recommended


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A study of the ma'imum and the minimum #oid si1es re#eals neither a particular trend nor

consistency "n all the HPC mi'tures the reference mi' at .5 days ga#e ma'imum #oid si1es amongst

the largest #alues (+,(0B5- mm$)3 +,%($74, mm

$)3 +.(,... mm$) and +$(0--4 mm

$) : Tables $

to 6) This can possibly e'plain the #ariations obser#ed in the percentage porosity as recorded Some

e'cess !ater !as trapped !ithin the concrete hence creating large air #oids !hich are not #oidcreated by SAP These large air #oids form part of !hat !as used to calculate total #oid but !ere

e'cluded in the calculation of SAP #oids 2 The minimum #oid si1e in all the concrete samples !ere

ho!e#er same #alue (---,$ mm$) This is because the CT scanning on the HPC !as carried out at

,-- Em3 hence the lo!est air #oids that can be detected are those abo#e ,-- Em The a#erage #oid

si1e too did not gi#e a particular trend or consistency This is because of the presence of some

arbitrary large #oid si1es !hich thereby influenced the #alue of a#erage #oid si1e calculated A study

of the triplicate samples !ill surely gi#e a better conclusion on the influence of SAP contents and /

or mi'ture type on the air #oid distribution of HPC

The optimum SAP content for the HPC mi'tures can ho!e#er be taken as -$ (since the outliers as

obser#ed on &igure 7 are mainly noticed at SAP contents higher than -$ 2) The presence of a high

number of large air #oids ( ,0-- mm $) in HPC of higher SAP contents can therefore be responsible

for obser#ed loss in strength and relati#e lo! mechanical properties pointed out in pre#ious studies

=.B .5 .7 ,0> HPC made of high / definitely has a lesser need for internal curing and hence the

less the demand for SAP as "C:agent SAP air #oids cannot ho!e#er be said to be detrimental to the

porosity of HPC as SAP #oids for all SAP containing HPC mi'tures studied lies belo! . : 02 !ith the

a#erage porosity #alues all belo! $2 This is belo! the e'pected SAP #oids calculated based on

additional !ater pro#ided for SAP and also the de:moulded concrete porosity for the HPC mi'tures

The reference mi' for the HPC !ith -$ / (ie +$) ga#e a total porosity #alue similar to same

mi'tures containing SAP This can be due to e'cess air bubbles created by superplastici1er since

concrete at higher / has less need for !ater reducing agents The mi'tures containing &ly Ash and

Core' Slag as cement e'tenders (+,and +,%3 at / of -.) ho!e#er sho!ed a good trend of the

influence of SAP on HPC !ith the SAP air #oids been about 0- 2 of e'pected SAP pore content

The SAP type can be ad8udge to influence the air #oid content in all HPC specimens as the #oid

#olumes for Sp. is taken as about double the #oid #olumes in Sp, This is because as obser#ed in $,

abo#e Sp. (-/0-- Em) is double Sp, (-/$-- Em) in si1e


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0 0.1 0.2 0.3 0.4 0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

M1Sp1 M1DSp1 M2Sp1 M3Sp1

SAP content (%)

Void (%)

(a) Sp, Moid series after .5 days curing

0 0.1 0.2 0.3 0.4 0.5

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

M1Sp2 M1DSp2 M2Sp2 M3Sp2

SAP content (%)

Void (%)

(b) Sp.Moid series after .5 days curing

'(re 7:SAP #oid 2 against SAP content 2


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Tab$e ) Summary of "nfluence of SAP contents and curing age on #oid distribution for + ,; HPC

Curing Age Influence Ref SAP1 SAP2

M1-28D Series M1 M1Sp10.2 M1Sp10.3 M1Sp10.4 M1Sp20.2 M1Sp20.3 M1Sp20.4

SAP pore epec!e"# 0.00 3.40 $.01 6.$6 3.40 $.01 6.$6

De-%oul"e" Porosi!# 0.$8 4.3' 6.$6 6.66 2.43 $.6( 6.1(

)o of *oi"s 1$00 +% 3$ 4$ 48 $2 3$ $( (0

SAP Voi" , 0.00 1.2$ 1.$1 2.(( 2.1' 3.0$ 4.40

o!l Porosi!& , 1.4( 2.03 2.'1 4.42 2.$3 3.$3 $.06

M Voi" Si/e %%3 $(.80$3 23.1448 6$.$331 4'.$11' 14.(461 11.2816 $$.'81'

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.1$3$ 0.0$8$ 0.08(8 0.0(0( 0.0$$4 0.10(0 0.0$$6

M1-$6D Series M1 M1Sp10.2 M1Sp10.3 M1Sp10.4 M1Sp20.2 M1Sp20.3 M1Sp20.4

)o of *oi"s 1$00 +% 3( 3( 3( 64 42 6( 36

SAP Voi" , 0.00 1.30 1.8( 2.60 1.68 3.'1 2.23

o!l Porosi!& , 1.68 2.22 2.68 4.02 2.0( 4.4' 2.$6

M Voi" Si/e %%3 $$.0342 2$.$84$ $(.4$26 1$.(61( 46.'3(( 32.86$1 121.80$0

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3

0.028( 0.10(' 0.06$6 0.0$(0 0.063( 0.1161 0.0604M1-'0D Series M1 M1Sp10.2 M1Sp10.3 M1Sp10.4 M1Sp20.2 M1Sp20.3 M1Sp20.4

)o of *oi"s 1$00 +% 2' 4$ $3 $$ 3' 1$2 $1

SAP Voi" , 0.00 1.3$ 2.21 2.$( 1.63 3.88 2.6'

o!l Porosi!& , 1.48 2.21 3.31 4.40 2.00 $.31 3.1(

M Voi" Si/e %%3 60.6$63 ((.'44( $$.6$84 38.8080 30.221( 31.2426 61.04(6

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.0861 0.0('4 0.0888 0.08(8 0.0$34 0.1664 0.0$60

Tab$e /:Summary of "nfluence of SAP contents and curing age on #oid distribution for + ,%; HPC


M1D-28D Series M1D M1DSp10.2 M1DSp10.3 M1DSp10.4 M1DSp20.2 M1DSp20.3 M1DSp20.4

SAP pore epec!e"# 0.00 3.40 $.01 6.$6 3.40 $.01 6.$6

De-%oul"e" Porosi!# 0.20 3.'' 4.4( 6.38 3.$2 4.'6 6.3'

)o of *oi"s 1$00 +% 13 32 26 1( 3' 2' 4$

SAP Voi" , 0.00 1.60 1.'2 0.(3 2.(1 1.(0 2.6$

o!l Porosi!& , 0.82 2.31 2.60 1.08 3.0$ 1.'8 3.03

M Voi" Si/e %%3 3'.406' 41.(4$$ 1(.23'1 26.40'( 22.1(18 23.41$0 14.$('8

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.108$ 0.06$6 0.0$1( 0.03'1 0.081$ 0.1003 0.0'34

M1D-$6D Series M1D M1DSp10.2 M1DSp10.3 M1DSp10.4 M1DSp20.2 M1DSp20.3 M1DSp20.4

)o of *oi"s 1$00 +% 2$ 21 2$ 32 21 1$4 21

SAP Voi" , 0.00 0.64 1.18 1.8' 1.(3 3.46 1.4(

o!l Porosi!& , 1.32 1.03 1.62 2.(( 1.'1 4.'2 1.68M Voi" Si/e %%3 3'.$014 42.2$3' 66.'(1' 31.13(4 13.1822 6(.111( 31.02$6

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.06'$ 0.0($2 0.0(16 0.0602 0.0818 0.1'(( 0.0'$(

M1D-'0D Series M1D M1DSp10.2 M1DSp10.3 M1DSp10.4 M1DSp20.2 M1DSp20.3 M1DSp20.4

)o of *oi"s 1$00 +% 2( 2' 4$ 22 4( 22 26

SAP Voi" , 0.00 1.$$ 1.(3 1.86 2.1$ 2.40 2.4$

o!l Porosi!& , 0.86 2.2' 2.6$ 2.63 2.$$ 2.61 2.6'

M Voi" Si/e %%3 28.21$' 1$.2320 3$.8$(1 21.'362 23.82(6 1(.2884 1$.4103

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.14(( 0.0608 0.081( 0.0$'3 0.0641 0.0(84 0.10$1

N'pected pore content by #olume based on the .0 g/g pore absorption used for pro#ision of additional !ater

calculated taking the s!ollen SAP as a spherical substanceNNPorosity calculated #olumetrically using %e:moulded density in comparison to designed density


17/26

Tab$e 3:Summary of "nfluence of SAP contents and curing age on #oid distribution for + .; HPC



SAP pore epec!e"# 0.00 2.8$ 4.21 $.$3 2.8$ 4.21 $.$3

De-%oul"e" Porosi!# 0.1( 2.3( 3.'8 $.4( 1.88 4.06 $.38

)o of *oi"s 1$00 +% 63 $0 63 4( '8 118 1$(

SAP Voi" , 0.00 2.01 1.'1 1.1' 2.$1 3.12 3.12

o!l Porosi!& , 2.33 3.0$ 3.6$ 2.22 3.3' 4.1' 4.6$

M Voi" Si/e %%3 122.1'$0 101.0430 $2.((68 8(.1312 43.'62' 8(.0(6( $3.$381

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.124( 0.0640 0.1244 0.11'' 0.146' 0.1'0( 0.24(4


)o of *oi"s 1$00 +% 4' $0 (0 44 43 36 1'$

SAP Voi" , 0.00 0.'3 1.3( 1.14 1.86 2.00 2.84

o!l Porosi!& , 2.2' 1.(1 3.02 2.03 2.23 2.3$ 4.(2

M Voi" Si/e %%3 28.63$1 '3.'300 84.8632 34.1$48 $2.4$60 4'.'$$1 (2.2334

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3

0.0((0 0.0(0( 0.1161 0.0881 0.12'3 0.0'0' 0.3(34M2-'0D Series M2 M2Sp10.2 M2Sp10.3 M2Sp10.4 M2Sp20.2 M2Sp20.3 M2Sp20.4

)o of *oi"s 1$00 +% 33 4( 36 6( 8$ 40 10(

SAP Voi" , 0.00 1.44 1.(( 2.0$ 2.1' 1.'8 2.8'

o!l Porosi!& , 1.(8 2.44 2.60 3.1' 2.'$ 2.3( 3.88

M Voi" Si/e %%3 (8.'6'6 46.86(2 41.0228 14.31(6 24.(034 34.($'1 28.$$'3

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.0'13 0.0680 0.0648 0.0(33 0.2126 0.102' 0.1(('

Tab$e 4:Summary of "nfluence of SAP contents and curing age on #oid distribution for + $; HPC



SAP pore epec!e" 0.00 2.64 3.'1 $.14 2.64 3.'1 $.14

De-%oul"e" Porosi!& 1.$8 3.2$ 6.00 6.00 3.'2 3.$6 4.$4

)o of *oi"s 1$00 +% 6$ $0 $( 1'1 1(1 11' 1''

SAP Voi" , 0.00 2.2( 2.32 1.'4 4.04 4.0' 3.33

o!l Porosi!& , 3.$4 3.8$ 4.12 $.(3 $.63 $.26 $.23

M Voi" Si/e %%3 $0.0416 14.261( 20.4162 103.''10 86.8118 $3.210( 48.4244

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.11$6 0.0821 0.0'30 0.2443 0.1(42 0.1$(6 0.21(0


)o of *oi"s 1$00 +% $3 43 42 1'6 84 14' 113

SAP Voi" , 0.00 1.($ 1.3' 2.23 3.0$ 3.34 3.($

o!l Porosi!& , 2.10 2.84 2.33 6.0$ 3.86 4.(1 4.83

M Voi" Si/e %%3 22.0$4( 38.$81( 46.$664 3'.6((1 $$.8621 60.343$ 2$.2$84

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.118$ 0.0((' 0.0'1$ 0.1'(3 0.18$' 0.1('0 0.1$08

M3-'0D Series M3 M3Sp10.2 M3Sp10.3 M3Sp10.4 M3Sp20.2 M3Sp20.3 M3Sp20.4

)o of *oi"s 1$00 +% 34 3$ 64 (0 $1 $2 104

SAP Voi" , 0.00 1.04 1.'8 2.06 2.44 2.44 3.1'

o!l Porosi!& , 1.'8 2.41 3.4' 3.8$ 2.'$ 2.'2 4.1$

M Voi" Si/e %%3 31.(1$1 28.(1(( 12.1826 (1.184$ 4$.''14 100.'($0 26.2220

Min. Voi" Si/e %%3 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013 0.0013

A*. Voi" Si/e %%3 0.06(' 0.1026 0.1134 0.1008 0.1$33 0.1634 0.146$

N'pected pore content by #olume based on the .0 g/g pore absorption used for pro#ision of additional !atercalculated taking the s!ollen SAP as a spherical substanceNNPorosity calculated #olumetrically using %e:moulded density in comparison to designed density


18/26

)"/ I+$(e+ce o c(r#+' a'e o+ a#r 0o#d d#str#b(t#o+

Tables $ to 6 present summary of the result of influence of curing age SAP type and SAP contents on

the SAP air #oid distribution of the #arious HPC specimens &igures ,- to ,$ on the other hand sho!

the trend of the cumulati#e small air #oid #olume (ie all air #oids belo! ,0-- Em in si1e) present in

the #arious HPC This !as to in#estigate influence of curing age SAP type and contents on the

pattern of air #oid distribution in the respecti#e HPC mi'tures Although a single sample of each

specimen !ere analysed a total of 54 HPC specimens !ere studied using the CT scanner

The results in Tables $ and 4 re#eal a trend that for +,and +,%(/ F -. in reference mi') the total

#oids 2 decreased as the hydration period increased The SAP #oids !ere also noted to increase as

the SAP si1e and contents increased at all the respecti#e hydration periods for both HPC mi'es A

closer e'amination of the number of air #oids larger than ,0-- Em (diameter) as presented in the

tables gi#es a consistent #alue range of $- ; B- !ith some fe! outliers (pink colour highlights in the

tables) !hile the ma'imum #oid si1es !as also obser#ed to be of similar #alue range of .- ; B- mm $

but for t!o e'tremes : ,, mm$and ,., mm$(blue colour highlights) The pattern of the cumulati#e

small #oids 2 present in the respecti#e HPC (&igure 7) also ga#e similar trends !ith de#iation

obser#ed in the specimens marked as outliers (eg +,Sp.-$:06% in &igure ,-(d)3 +,%Sp,-4:06% and

+,%Sp.-4:06% in &igure ,, (c d)) ffect of large air #oids ( ,0-- Em) !as also noted to be glaring

in the total #oid calculated for these samples "t can thereby be inferred ho!e#er from this study that

for #ery lo! / mi'es SAP addition made additional internal !ater a#ailable for longer period of

cement hydration leading to possible increase in structure of the cement hydration products and

hence reduction in the #oids present

The HPC !ith Core' Slag as cement e'tender (+,%) !as ho!e#er noted to e'hibit the lo!est number

of large air #oids present for all hydration periods This implies that Core' Slag as a cement e'tender

enhanced better dispersal of the cement and other fine particles and good utilisation of mi'ing !ater

and thereby a possible good early age strength de#elopment3 a complimentary role to silica fume in

HPC A study of the particle si1e distribution particle structure of the #arious fine materials and the

general strength de#elopment of the HPC mi'tures !ill surely offer good ans!ers to this assertion

&igures ,. and ,$ sho! similar trends as abo#e in the cumulati#e small #oids present in + .and +$

(/ F -.0 and -$) specimens but !ith large numbers of #oid si1es abo#e ,0-- Em (ie large air

#oids) and great #ariation in the #alue of ma'imum #oid si1e present in these HPC mi'tures (pink and

blue colour highlights respecti#ely on the Tables 0 and 6) Moid #olume #alues abo#e B- mm $ !ere

noted to be more in these HPC samples !ith the specimens at .5 %ays hydration e'hibiting greater

proportion of them !hile some reference mi'es also contain #ery large air #oid such as ,.. mm $ in

#olume (+. :.5% in Table 0) The numbers of large #oids !ere consistently #ery high (5- ; .--) in the

+$mi'tures3 implying that the additional !ater pro#ided for the SAP addition got collated to amount to

these large air #oids The SAP #oids can ho!e#er still generally be ad8udged to decrease as the

curing age increases despite the higher number of outliers reported for these HPC mi'tures A better


19/26

inference on this !ill emerge if triplicate samples of these specimens are analysed as there are

possibilities that some single specimen e'amined might be the poor specimen of the particular batch

The presence of large numbers of air #oid #olumes abo#e ,0-- Em in these HPC mi'tures especially

+$mi'tures e#en after 7- days of curing (Table 6) is a confirmation that at this / ratios addition of

SAP for internal curing purposes might not be re


20/26

0

500

1000

1500

2000

0.0

1.0

2.0

3.0

4.0

5.0

M1-28D

M1Sp10.2-28D

M1Sp10.3-28D

M1Sp10.4-28D

Void Diameter #+m$

Void Content #,$

0

500

1000

1500

2000

0.0

1.0

2.0

3.0

4.0

5.0

M1-28D

M1Sp20.2-28D

M1Sp20.3-28D

M1Sp20.4-28D

Void Diameter #+m$

Void Content #,$

(a) +,; HPC !ith SP,at .5 %ays (b) +,; HPC !ith SP.at .5 %ays

0

500

1000

1500

2000

0.0

1.0

2.0

3.0

4.0

5.0

M1-56D

M1Sp10.2-56D

M1Sp10.3-56D

M1Sp10.4-56D

Void Diameter #+m$

Void Content #,$

0

500

1000

1500

2000

0.0

1.0

2.0

3.0

4.0

5.0

M1-56D

M1Sp20.2-56D

M1Sp20.3-56D

M1Sp20.4-56DVoid Diameter #+m$

Void Content #,$

(c) +,; HPC !ith SP,at 06 %ays (d) +,; HPC !ith SP.at 06 %ays

0

1000

2000

0.00

1.00

2.00

3.00

4.00

5.00

M1-90D

M1Sp10.2-90D

M1Sp10.3-90D

M1Sp10.4-90D

Void Diameter #+m$

Void Content #,$

0

1000

2000

0.00

1.00

2.00

3.00

4.00

5.00

M1-90D

M1Sp20.2-90D

M1Sp20.3-90D

M1Sp20.4-90D

Void Diameter #+m$

Void Content #,$


21/26

(e) +,; HPC !ith SP,at 7- %ays (f) +,; HPC !ith SP.at 7- %ays

'(re 18:"nfluence of Curing Age on Moid Content of (.0 ' .0 ' 0- mm $) +, ; HPC Samples

0

500

1000

1500

2000

0.0

0.5

1.0

1.5

2.0

2.5

3.03.5

4.0

M1D-28D

M1DSp10.2-28D

M1DSp10.3-28D

M1DSp10.4-28D

Void Diameter #+m$

Void Content #,$

0500

10001500

2000

0.0

0.5

1.0

1.5

2.0

2.5

3.03.5

4.0

M1D-28D

M1DSp20.2-28D

M1DSp20.3-28D

M1DSp20.4-28DVoid Diameter #+m$

Void Content #,$

(a) +,%; HPC !ith SP,at .5 %ays (b) +,%; HPC !ith SP.at .5 %ays

0

500

1000

1500

2000

0.0

0.51.0

1.5

2.0

2.5

3.0

3.5

4.0

M1D-56D

M1DSp10.2-56D

M1DSp10.3-56D

M1DSp10.4-56D

Void Diameter #+m$

Void Content #,$

0

500

1000

1500

2000

0.0

0.51.0

1.5

2.0

2.5

3.0

3.5

4.0

M1D-56D

M1DSp20.2-56D

M1DSp20.3-56D

M1DSp20.4-56D

Void Diameter #+m$

Void Content #,$

(c) +,%; HPC !ith SP,at 06 %ays (d) +,%; HPC !ith SP.at 06 %ays


22/26

0

500

1000

1500

2000

0.0

0.5

1.01.5

2.0

2.5

3.0

3.5

4.0

M1D-90D

M1DSp10.2-90D

M1DSp10.3-90D

M1DSp10.4-90D

Void Diameter #+m$

Void Content #,$

0

500

1000

1500

2000

0.0

0.5

1.01.5

2.0

2.5

3.0

3.5

4.0

M1D-90D

M1DSp20.2-90D

M1DSp20.3-90D

M1DSp20.4-90D

Void Diameter #+m$

Void Content #,$

(e) +,%; HPC !ith SP,at 7- %ays (f) +,%; HPC !ith SP.at 7- %ays

'(re 11:"nfluence of Curing Age on Moid Content of (.0 ' .0 ' 0- mm $) +,% ; HPC Samples

0

500

1000

1500

2000

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

M2-28D

M2Sp10.2-28D

M2Sp10.3-28D

M2Sp10.4-28D

Void Diameter #+m$

Void Content #,$

0500

10001500

2000

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

M2-28D

M2Sp20.2-28D

M2Sp20.3-28D


Void Content #,$

(a) +.; HPC !ith SP, at .5 %ays (b) +.; HPC !ith SP.at .5 %ays

0

500

1000

1500

2000

0.0

0.5

1.0

1.5

2.0

2.53.0

3.5

4.0

M2-56D

M2Sp10.2-56D

M2Sp10.3-56D

M2Sp10.4-56D

Void Diameter #+m$

Void Content #,$

0

500

1000

1500

2000

0.0

0.5

1.0

1.5

2.0

2.53.0

3.5

4.0

M2-56D

M2Sp20.2-56D

M2Sp20.3-56D

M2Sp20.4-56D

Void Diameter #+m$

Void Content #,$

(c) +.; HPC !ith SP,at 06 %ays (d) +.; HPC !ith SP.at 06 %ays


23/26

0

500

1000

1500

2000

0.0

0.5

1.01.5

2.0

2.5

3.0

3.5

4.0

M2-90D

M2Sp10.2-90D

M2Sp10.3-90D

M2Sp10.4-90D

Void Diameter #+m$

Void Content #,$

0

500

1000

1500

2000

0.0

0.5

1.01.5

2.0

2.5

3.0

3.5

4.0

M2-90D

M2Sp20.2-90D

M2Sp20.3-90D

M2Sp20.4-90D

Void Diameter #+m$

Void Content #,$

(e) +.; HPC !ith SP,at 7- %ays (f) +.; HPC !ith SP.at 7- %ays

'(re 12:"nfluence of Curing Age on Moid Content of (.0 ' .0 ' 0- mm $) +. ; HPC Samples

010

0020

00

0.00

1.00

2.00

3.00

4.00

5.00

M3-28D

M3Sp10.2-28D

M3Sp10.3-28D

M3Sp10.4-28D

Void Diameter #+m$

Void Content #,$

010

0020

00

0.00

1.00

2.00

3.00

4.00

5.00

M3-28D

M3Sp20.2-28D

M3Sp20.3-28D

M3Sp20.4-28D

Void Diameter #+m$

Void Content #,$

(a) +$; HPC !ith SAP, at .5 %ays (b) +$; HPC !ith SAP. at .5 %ays

0

1000

2000

0.00

1.00

2.00

3.00

4.00

5.00

M3-56D

M3Sp10.2-56D

M3Sp10.3-56D

M3Sp10.4-56D

Void Diameter #+m$

Void Content #,$

0

1000

2000

0.00

0.50

1.00

1.50

2.002.50

3.00

3.50

4.00

M3-56D

M3Sp20.2-56D

M3Sp20.3-56D


Void Content #,$

(c) +$; HPC !ith SAP, at 06 %ays (d) +$; HPC !ith SAP. at 06 %ays


24/26

0

1000

2000

0.00

0.50

1.001.50

2.00

2.50

3.00

3.50

M3-90D

M3Sp10.2-90D

M3Sp10.3-90D

M3Sp10.4-90D

Void Diameter #+m$

Void Content #,$

0

1000

2000

0.00

0.50

1.001.50

2.00

2.50

3.00

3.50

M3-90D

M3Sp20.2-90D

M3Sp20.3-90D

M3Sp20.4-90D

Void Diameter #+m$

Void Content #,$

(e) +$; HPC !ith SAP, at 7- %ays (f) +$; HPC !ith SAP. at 7- %ays

'(re 1):"nfluence of Curing Age on Moid Content of (.0 ' .0 ' 0- mm $) +$ ; HPC Samples

/ CONCLUION AND RECOMMENDATION

"nfluence of SAP addition and curing age on the air #oids distribution in HPC ha#e been e'amined #ia

a $% #olume analysis using computed tomography (CT) scanner for HPC mi'tures of different !ater/

binder binder types and SAP types Also studied !ith the CT scanner is the dry SAP particles si1e

distribution shape and sphericity The result re#eals that

a CT scanning is a good tool for studying the air #oids in concrete cement pastes and HPC Afast approach and representati#e concrete specimen (0- mm ' ,-- mm cylinder) enhanced

clear e'amination of the HPC !ith little or no modification to the cast specimenb The SAP particles are of #aried si1es mostly angular and irregular in shape and not totally

spherical The dry SAP particle si1e distribution analysed using CT scanner (SP,: -/$-- Em3

SP.: -/0-- Em) agrees !ith the manufacturers specification (SP, $-- Em3 SP . 6-- Em)c All the HPC?s mi'tures had micro:air #oids present irrespecti#e of SAP contents SAP created

#oids are ho!e#er more and follo!s same pattern as the distribution of the dry SAP particlesd The HPC mi'tures had large #olume air #oids present possibly being a result of high

concentration of superplastici1er in the HPC The fre


25/26

ACKNO9LED!EMENT

e ackno!ledge the follo!ing +r Duillaume Oeanson (Construction Product +anager) SI& &loerger

: AC de +ilieu' 4.,6$ AI%J"@9 Cede' ; &JAIC3 %a#y Penhard &" Misualisation Science

Droup3 %r Anton du Plessis and Stephan le Jou' CT Scanner @nit Central Analytical &acilities

(CA&) Stellenbosch @ni#ersity South Africa for the assistance recei#ed in materials procurement use

of facilities soft!ares and time input in the analysis

RE&ERENCE

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=.> S I ,.$7- ; . (.---) QTesting of hardened concrete : making and curing specimen forstrength testsR S" ondon

=$> AC" THPC/TAC (,777) QAC" %efines High Performance Concrete ; the Technical Acti#itiesCommittee Jeport (Chairman : HD Jussell)R !!!concreteorg

=4> T C Po!ers Copeland H +ann QCappilary continuity or discontinuity in cementpastes Capillary Continuity Gr %iscontinuity in Cement PastesR ulleting M (,707 ,,- ,,:,.

=0> AC" ($-5 : .,$) J,$ QJeport on internally cured concrete using pre!etted absorpti#elight!eight aggregateR !!!concreteorg

=6> G + Oensen P ura QTechni ol#er G Oensen (eds) Q"nternal curing of concrete State:of:the:art report of the J"+technical committee ,76:"CCR J"+ Jeport 4, .--B "SI 7B5:.:$0,05:-5.:- e:"SI 7B5:.:$0,05:-5.:-

=5> S austsen % P ents + T Hasholt G + Oensen QCT measurement of Small #oids inconcreteR in G + Oensen +T Hasholt S austsen (eds) @se of Superabsorbent Polymersand Gther Ie! Additi#es in Concrete PJ-B4 J"+ Publications Technical @ni#ersity of%enmark yngby %enmark .-,- p,0$:,6.

=7> M +echtcherine H Jeinhardt (eds) QApplication of superabsorbent polymers in concreteconstruction State:of:the:art report of the J"+ TC ..0:SAPR Springer Heidelberg/Dermany.-,. "SI 7B5:74:--B:.B$.:5

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=,,> S I 45- : ,, VAdmi'tures for concrete mortar and grout : Test methods for determination ofair:#oids characteristics in hardened concreteV S" ondon

=,.> AST+ C40B ; ,-a QStandard test method for microscopical determination of parameters of theair:#oid systems in hardened concreteR @SA !!!astmorg

=,$> % P ent1 P + Halleck A S Drader O Joberts Q&our:dimensional 9:ray

microtomography study of !ater mo#ement during internal curingR in G+ Oensen P ura o#ler (eds) Molume Changes of Hardening Concrete Testing and +itigation PJ-0. J"+Publications Technical @ni#ersity of %enmark yngby %enmark .--6 p ,,:.-

=,4> C SchrWfl M +echtcherine + Dorges QJelation bet!een the molecular structure and theefficiency of superabsorbent polymers (SAP) as concrete admi'tures to mitigate autogenousshrinkageR Cement and Concrete Jesearch 4. (6) (.-,.) 560:5B$

=,0> O Gla!uyi P oshoff QCompressi#e strength of high:performance concrete !ithabsorption capacity of super:absorbing:polymers (SAP)R in Jesearch and Applications inStructural ngineering +echanics and Computation ; ingoni (d) X .-,$ Taylor &rancisDroup ondon .-,$ "SI 7B5:,:,$5:---6,:. Pp ,6B7:,65$

=,6> + S Shetty QConcrete technology : theory and practiceR Ie! %elhi "ndia S Chand andCompany imited (.--4)

=,B> O Gla!uyi P oshoff Q"nfluence of particle si1e distribution on compressi#e strength andelastic modulus of high performance concreteR in "nternational Conference on Ad#ances in
http://www.concrete.org/http://www.concrete.org/http://www.concrete.org/http://www.astm.org/http://www.concrete.org/http://www.concrete.org/http://www.astm.org/http://www.concrete.org/


26/26

Cement and Concrete Technology in Africa (ACCTA) Oohannesburg South Africa .-,$ Pp5.0:5$$

=,5> S I ,7B ; , (.---) QCement ; composition specifications and conformity criteria forcommon cementsR S" ondon

=,7> P C AKtcin QHigh:performance concreteR Taylor &rancis (,775)

=.-> S I ,.$0- ; , (.---) QTesting of fresh concrete ; SamplingR S" ondon=.,> S I ,.$0- ; 0 (.---) QTesting of fresh concrete : &lo! Table TestR S" ondon

=..> S I ,.$7- ; , (.---) QTesting of hardened concrete : shape dimension and otherre &" Misualisation Science Droup QA#i1o &ire (#ersion 5-) : $% Analysis soft!are for Scientificand "ndustrials %ataR (.-,$) !!!#sg$dcom

=.0> Molume Draphics QMDStudio +a' ..: Application soft!are for analysis and #isualisation ofindustrial computed tomography/ #o'el dataR (.-,$) !!!#olumegraphicscom

=.6> A %u Plessis O Gla!uyi P oshoff S e Jou' O Petren QSimple and fast method for$% porosity analysis of concrete samples using 9:ray computed tomographyR (submitted for

publication) (.-,4)

=.B> + T Hasholt + H S Oespersen G + Oensen Q+echanical properties of concrete !ith SAP :part " %e#elopment of compressi#e strengthR in G + Oensen +T Hasholt S austsen (eds)@se of Superabsorbent Polymers and Gther Ie! Additi#es in Concrete PJ-B4 J"+Publications Technical @ni#ersity of %enmark yngby %enmark .-,- p ,,B::,.6

=.5> Craeye + Deirnaert D % Schutter QSuper absorbing polymers as an internal curing agentfor mitigation of early:age cracking of high:performance concrete bridge decksR Constructionand uilding +aterials .0 (,) (.-,,) ,:,$

=.7> + T Hasholt G + Oensen ol#er S huto#sky3 QCan superabsorbent polymers mitigateautogenous shrinkage of internally cured concrete !ithout compromising the strengthYRConstruction and uilding +aterials $, (.-,.) ..6:: .$-

=$-> O Gla!uyi P oshoff Q$% #oid analysis of high performance concrete containingsuperabsorbent polymersR submitted for presentation at "nternational Conference onApplication of Superabsorbent Polymers and Admi'ture in Concrete Construction Technical@ni#ersity %resden Dermany September .-,4
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3D Volume Analysis of Influence of SAP Contents and Curing Age on Air Void Distribution in High