effect of internal curing with superabsorbent polymers on

Research ArticleEffect of Internal Curing with Superabsorbent Polymers on BondBehavior of High-Strength Concrete

Xiao Lei1 Rui Wang1 Hanwan Jiang 2 Faxiang Xie1 and Yanni Bao3

1College of Civil and Transportation Engineering Hohai University 1 Xikang Road Nanjing Jiangsu 210098 China2College of Engineering Mathematics and Science Department of Civil Engineering University of Wisconsin Platteville1 University Plaza Platteville WI 53818 USA3Tongji Architectural Design (Group) Co Ltd Shanghai 20092 China

Correspondence should be addressed to Hanwan Jiang jianghanuwplattedu

Received 18 November 2020 Revised 2 December 2020 Accepted 22 December 2020 Published 31 December 2020

Academic Editor Haohui Xin

Copyright copy 2020 Xiao Lei et al)is is an open access article distributed under the Creative Commons Attribution License whichpermits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

High-strength concrete (HSC) is widely used in engineering due to its high strength and durability However because of its lowwater-to-cement ratio external curing water hardly enters the dense internal structure of HSC so that high self-desiccationshrinkage often takes place As a result superabsorbent polymers (SAP) are added as an internal curing material to effectivelyreduce the shrinkage of high-performance concrete Meanwhile the bond performance between reinforcing steel and SAP HSCconcrete remains unknown In this paper the bond performance of HSC mixed with SAP is studied by pull-out tests and theresults were obtained as follows (1) the bond strength of HSCmixed with SAP increased first and then decreased with the increaseof SAP content (2) the slip at ultimate bond strength of HSC with SAP decreased with the increase of compressive strength (3) aprediction model of the stress-slip relationship between steel rebars and HSC was established

1 Introduction

High-strength concrete has higher strength and durabilitythan conventional concrete due to its low water-to-cementratio denser internal structure and low permeability [1]However autogenous shrinkage may take place when thewater-to-cement ratio is below the critical level resulting incracking and reduction of the structurersquos serviceability [2ndash5]Hence internal curing has been employed to prevent au-togenous shrinkage in high-strength concrete by replacing apercentage of normal-weight aggregates with lightweight-weight aggregates [6 7] superabsorbent polymer (SAP) orother expansive materials [8 9] SAP has been extensivelystudied due to its advantages of being able to mitigate au-togenous shrinkage and prevent self-desiccation [10ndash15]Multiple studies have proved that SAP can effectively reducethe self-shrinkage of HSC [16ndash18] while there is no con-sensus on the influence of SAP on the compressive strengthof HSC Some tests found that SAP would reduce thecompressive strength of HSC [19ndash22] but some other tests

found that SAP would increase the compressive strength ofHSC [23ndash26] It is reported that SAP content is one of thefactors that affect HSCrsquos compressive strength [27] Whilethere are many factors that influence compressive strengthof HSC such as the amount of compensated water type andSAP particle size the absorption desorption kinetic of SAPsand the interfacial properties between cement matrix andSAPs the authors only focus on the effect of SAP content oncompressive strength of HSC in this study

Meanwhile as a key parameter for structural designbond strength for HSC with SAP added has not been studiedyet Although there were many studies published on thebond strength of normal reinforced concrete [28ndash36] as wellas high-strength concrete [37ndash42] the law of bond strengthand the stress-slip relationship between HSC mixed withSAP and reinforcing steel remain unclear )e stress-sliprelationship of concrete is usually obtained from pull-outtests Various stress-slip models for normal concrete andhigh-performance concrete have been developed in manystudies [41ndash51] However the stress-slip response for high-

HindawiAdvances in Materials Science and EngineeringVolume 2020 Article ID 6651452 13 pageshttpsdoiorg10115520206651452

strength concrete mixed with SAP is still unknown In thispaper an experimental study has been carried out aimed atestablishing SAP content and compressive strength rela-tionship SAP content and HSC bond strength relationshipand the stress-slip model for HSC with SAP

2 Experimental Investigation

21 Material Properties )e cement used in this test is PO425 Portland cement with chemical composition shown inTable 1 Medium coarse sand and 5ndash16mm continuousgraded gravel were mixed with the cement to create concretewith a compression strength of 50MPa High efficiencypolycarboxylate superplasticizer was added as a water re-ducing agent Drying and absorbing states of SAP are shownin Figure 1 Standard structural rebars are 16mm in di-ameter shown in Figure 2 In )eory the internal curingwater should be the same for same water-to-cement ratioHowever when SAP is added water is partially absorbedsuch that more water is needed in addition to that for in-ternal curing)erefore the internal curing water is set to be20 times of the SAP content

)e mixture proportions of concrete used in the test areshown in Table 2

22 Required Internal CuringWater In order to ensure thatthe cement can reach the maximum hydration level theinternal curing water amount can be calculated according tothe following equation [52]

Mic Cf times CS times αmax (1)

where Mic is internal curing water mass required forcomplete hydration of cement Cf is the cement mass (kgm3) CS is the shrinkage of cement when it reaches 100hydration for general cement it is 007 and αmax is themaximum hydration degree when all water in SAP is usedfor cement hydration without evaporation loss generally itis [WC]036 (when WCle 036)

According to the theoretical calculation the internalcuring water amount is 3312 kgm3 but considering thatdifferent SAP contents were designed in the test the finalinternal curing water amount of S0 S1 S2 S3 and S8 wasdetermined to be 0 102 204 306 and 816 kgm3respectively

23 Concrete Preparation for Compressive Strength and Pull-Out Test A total of 6 specimens for pull-out test were madeas shown in Figure 3 )e rebar was embedded centrically inthe 150mmtimes 150mmtimes 150mm concrete cube )e stan-dard 28-day strength of the concrete is 50MPa )e em-bedment length of the rebar in the concrete block is 3 timesof rebar diameter (48mm) )e rebar was sheathed withPVC pipes for debonding on both ends of the concrete blockat a length of 34mm and 68mm respectively A shorterbond length 3 times rebar diameter instead of typically used5 times rebar diameter [53] was adopted in order to obtain acomplete stress-slip curve and prevent splitting

)ree 150mm concrete cubes were set for the com-pressive strength test )e concrete mixing is followed in asequence First of all cement coarse and fine aggregate anddry SAP were put together and mixed for 30 s then half ofthe water and the water reducing agent were added andmixed for another 2min after that the remaining half of thewater and the water reducing agent were poured and mixedfor additional 2min Once the mixing was completed themixture was immediately poured into molds )e specimenshave been cured for 28 days to achieve desirable strength

24 Experimental Process A hydraulic universal testingmachine was used for the test and an LVDT sensor was seton the specimen to measure the relative slip of steel bar andconcrete as shown in Figure 4(a) )e test was controlled bydisplacement and the loading rate was 03mmmin)e testended when the steel bar was pulled out or broken theconcrete specimen was damaged or reaches the specifieddisplacement Dynamic data collection was used to recordthe load value and the reading of the LVDT )e failuremode of all tests is deemed to be split failure from the visualinspection shown in Figure 4(b)

3 Experiment Results

31 Effect of SAP on Compressive Strength of HSC )ecompressive strength of HSCwith different content of SAP isshown in Figure 5 It indicates that a small amount of SAPcan increase the compressive strength of HSC but when thecontent exceeded the peak value the compressive strengthwas reduced When the SAP content was 01 of cementmass the compressive strength of concrete increases by455 when the SAP content was 02 03 and 08 ofcement mass the compressive strength of concrete de-creased by 984 2091 and 3333 respectively )eamount of SAP needed to achieve maximum compressivestrength is a trade-off analysis SAP reduces the shrinkage inconcrete and improves cement hydration which helps in-crease the compressive strength Meanwhile the addition ofSAP increases water diversion and porosity and thereforeresults in decreased compressive strength )is experimentshowed that the peak of compressive strength had beenachieved with 01 SAP addition

)e following equation was created to best fit the datapoints in Figure 5 with the goodness of fit R2 099

fcu fc28 d middot6389x

2minus 701x + 307

100x2

minus 1193x + 307 (2)

where fcu is the compressive strength of SAP concrete MPafc28 d is the 28-day compressive strength of ordinary con-crete MPa x is the SAP content

)e calculated and measured compressive strength ofSAP concrete are listed in Table 3 It shows that the dif-ferences between the calculated and measured values areminimal so that equation (2) can be adopted to represent theSAP content-compressive relationship

2 Advances in Materials Science and Engineering

32 Effect of SAP on Bond Strength of HSC )e equation forcalculating the bond strength is simply to use the pull-outforce divided by the contact area around the rebar as shownin the following equation

τu Pu

π dld (3)

where τu is the bond strength MPa Pu is the pull-out forceN d is the diameter of the steel bar mm and ld is the bondlength mm

)e bond strength for HSC with different SAP content istested and shown in Table 4 It can be seen from the table thata small amount of SAP could increase the bond strength ofHSC but if adding more than 01 of SAP the bondstrength was reducedWhen the SAP content was 01 of thecement mass the bond strength of concrete increased by892 when the SAP content was 02 03 and 08 ofthe cement mass the bond strength of concrete decreased by598 1455 and 2524 respectively

)e experimental results show that the bond strengthvariations with SAP content in HSC is similar to that ofcompressive strength It is worth noting that the addition ofSAP made the bond strength of concrete increase more thancompressive strength (Figure 6) For example adding 01of SAP caused 455 increase in compressive strength and892 in bond strength Similarly adding 02 03 and08 SAP caused 984 2091 and 3333 drawdown in

Table 1 Chemical composition of cement

Chemical composition Content ()SiO2 199Al2O3 46Fe2O3 30CaO 646SO3 237Na2O 006K2O 065MgO 078Clminus 001

(a)

(b)

Figure 1 Superabsorbent polymer (SAP) collapsed (a) swollen(b)

Figure 2 Rebars used in the experiments

Table 2 Mixture proportions of concrete

Serial number S0 S1 S2 S3 S8WC 0334 0334 0334 0334 0334Cement (kgm3) 510 510 510 510 510Water (kgm3) 170 170 170 170 170Internal curing water (kgm3) 0 102 204 306 816Coarse aggregate (kgm3) 1131 1131 1131 1131 1131Fine aggregate (kgm3) 636 636 636 636 636Water reducing agent (kgm3) 26 26 26 26 26SAP (kgm3) 0 051 102 153 408ldquoSrdquo in the serial number stands for SAP content

Advances in Materials Science and Engineering 3

compressive strength and 598 1455 and 2524 de-crease in bond strength )e correlation between bondstrength and compressive strength is discussed in Section33

33 Relationship between Compressive Strength and BondStrength of Concrete Mixed with SAP )ere have been anumber of studies carried out on the relationship betweenbond strength and compressive strength of concrete andrebar In these studies bond strength is expressed in terms ofthe exponent of compressive strength [29 33ndash35 39ndash42]

τb a fcprime( 1113857

b (4)

where τb is the bond strength in MPa fcprime is the cylinder

compressive strength in MPa and a and b are the constants)e authors of the literature [29 33] studied the rela-

tionship between cylinder compressive strength and bond

strength accounting for factors such as the minimumthickness of protective layer diameter of steel bars and bondlength of steel bars )e empirical equation and value forparameters a and b were given

a A + Bcmin

db

+ Cdb

ld (5a)

b 05 (5b)

where cmin is the minimum thickness of protective layermm db is the diameter of steel bars mm ld is the bondlength mm and A B and C are the constants

)e research results of literature [29 33] are shown inTable 5

In literature [34 35 39] the relationship between cyl-inder compressive strength and bond strength under theinfluence of minimum thickness of protective layer

3d (bond length)34 68Free end Loading end

Steel bar (d = 16mm)

150

150

Concrete

50 300

PVCPVC

500

16

Figure 3 Pull-out test specimen (all units in millimeters d is the rebar diameter)

(a) (b)

Figure 4 Pull-out test device (a) Test instrument (b) Split at failure


maximum thickness of protective layer diameter of steelbars bond length of steel bars and area of steel bars wasstudied a different function and value for a and b werederived and shown in the following equations

a Ald cmin + 05db( 1113857 + BAb1113858 1113859 01cmax

cmin+ 091113888 1113889 πdbld( 1113857

minus1

(6a)

b 025 (6b)

where ld is the bond length mm cmin is the minimumthickness of protective layer mm db is the diameter of steelbars mm Ab is the area of steel bars cmax is the maximumthickness of protective layer mm and A and B are theconstants

)e research results of literature [34 35 39] are shown inTable 6

In literature [39] experimental studies were conductedon concrete specimens with strength up to 90MPa and theexpressions of a and b values were obtained as shown below

a 41 (7a)

b 05 (7b)

In literature [41] bond strength of high-strength con-crete was studied and the expressions of a and b valuesobtained are shown in the following equation

a 165 (8a)

b 07 (8b)

030

32

34

36

38

40

42

44

46Co

mpr

essiv

e str

engt

h (M

Pa) 48

50

52

54

01 02 03 04 05SAP ()

Fitting curveExperimental data

06 07 08 09

Figure 5 Relationship between SAP content and compressive strength

Table 3 )eoretical and experimental results of compressive strength of SAP concrete

SAP dosage () Test compressive strength (MPa) )eoretical compressive strength (MPa) Error0 4927 4927 001 5151 5151 002 4442 4443 00203 3897 3898 00308 3285 3285 0

Table 4 Bonding strength of specimens

SAP dosage () Bond strength (MPa) Slip corresponding to bond strength (mm)0 3676 083301 4004 083602 3456 098603 3141 100508 2748 1126


According to literature [44] the ratio of compressivestrength of the 150mm cube to that of the standard cylinderis 08 so the cylinder compressive strength fc

prime of the concretewith 0 01 02 03 and 08 SAP content in this test is3942 4121 3554 3118 and 2628MPa respectively

)e relationship between the cylinder compressivestrength and bond strength obtained from the above cal-culation results and this test is shown in Figure 7

As seen in Figure 7 the models from the listed literaturesare not consistent with testing data for concrete mixed withSAP Equation (4) was used to best fit the data and the valuesfor a and b were obtained (a203 b 08) with R2 097Hence the bond strength and the cylinder compressivestrength relationship of SAP concrete can be expressed as

τb 203 fcprime( 111385708

(9)

where τb is the bond strength MPa fcprime is the cylinder

compressive strength MPa)e calculated and measured bond strengths for con-

crete specimens with various SAP content are shown in

Table 7 Since the difference between the two is within 5equation (9) is suitable for bond strength evaluation

Substituting equation (2) into equation (9) the bondstrength can be written as

τb 203 middot 08 middot fc28 d middot6389x2 minus 701x + 307100x2 minus 1193x + 307

1113890 1113891

08

(10)

where τb is the bond strength MPa fc28 d is the 28-daycompressive strength of ordinary concrete (MPa) and x isthe SAP content )e factor of 08 in the bracket is toconvert cylinder strength to cube strength

34 Slip and Compressive Strength Relationship Shen et al[42] proposed a nonlinear relationship between slip at ul-timate bond stress and compressive strength based on theirtest data Similar trend was observed in the experiment withSAP concrete Hence the nonlinear model in literature [42]is adopted in this study as shown below

s0 m

fcprime + n

(11)

where s0 is the slip at ultimate bond stress mm fcprime is the

cylinder compressive strength MPa m and n are theconstants

)e slip at ultimate bond stress of concrete mixed withSAP in this test is shown in Figure 8 )e factors of m and nin equation (11) were found to be m 4874 and n 1679through data fitting with goodness of fit R2 093 )en therelationship between the slip at ultimate bond stress s0 andcylinder compressive strength fc

prime can be written as

s0 4874

fcprime + 1679

(12)

00

5

10

15

20

25

30

35

40St

ress

(MPa

)

45

50

55

01 02 03 04 05SAP ()

Bond strengthCompressive strength

06 07 08

Figure 6 Comparison of bond strength and compressive strength of concrete mixed with SAP

Table 5 Values of A B and C in different tests

Serial number A B COrangun [33] 010 025 415Chapman [29] 029 0282 4734

Table 6 Values of A and B in different tests

Serial number A BDarwin [34] 15 51Zuo [39] 143 562ACI [35] 143 574


)en the tested and theoretical slip from equation (12) atultimate bond stress for HSC with various SAP contents arelisted and compared in Table 8

35 e Prediction Model of Stress-Slip Relationship betweenSteel Bars and HSC Mixed with SAP Various stress-slipmodels have been developed in the past two decades [41ndash51]showing that there is a clear relationship between bond stressand slip In this study the BPE model [51] was used

τ τmaxs

s01113888 1113889

α

(13a)

It can also be expressed as

ττmax

s

s01113888 1113889

α

(13b)

where τ is the bond stress value MPa s is the slip corre-sponding to bond stress mm τmax is the ultimate bondstrength MPa s0 is the slip at ultimate bond strength mmand α is a constant

Performing best fitting analysis α values for SAP contentof 0 01 02 03 and 08 were found to be 0247701367 019 02101 and 01615 respectively as shown in

Figure 9 )en the mean of the five numbers 01892 wastaken for the finalized stress-slip relationship of SAP con-crete as shown in the following equation

τ τmaxs

s01113888 1113889

01892

(14)

Combined with equation (2) equation (9) equation (10)and equation (13) bonding performance of UPC with SAPcan be expressed as follows


2minus 701x + 307

100x2

minus 1193x + 307 (15a)

fcprime 08fcu (15b)

τmax 203 fcprime( 111385708

(15c)

s0 4874

fcprime + 1679

(15d)

τ τmaxs

s01113888 1113889

01892

(15e)

500

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

10 15 20 25 30Cylinder compressive strength (MPa)

Test dataOrangun model [33]Chapman model [29]Darwin model [36]

Zuo model [37]ACI design model [38]Lee model [39]Shen model [41]

35 40 45

Figure 7 Relationship between bond strength and cylinder compressive strength of different models

Table 7 )eoretical and experimental results of bond strength of SAP concrete

SAP content () Test bond strength (MPa) )eoretical bond strength (MPa) Error0 3676 3837 43801 4004 3976 07002 3456 3533 22303 3141 3182 13108 2748 2775 098


2608

085

09

095

1

105

11

s 0 (m

m)

115



38 40 42

Figure 8 Relationship between slip at ultimate bond stress and cylinder compressive strength

Table 8 )eoretical and experimental results of slip at ultimate bond stress for HSC with various SAP contents

SAP dosage () Tested slip at ultimate bond stress (mm) )eoretical slip at ultimate bond stress (mm) by equation (12) Error ()0 0833 0867 40801 0836 0840 04802 0986 0931 55803 1005 1016 10908 1126 1132 053

1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01


02 03Bond stress ratio

04 05 06 07 08 09 1

(a)

Figure 9 Continued



1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03

Bond stress ratio04 05 06 07 08 09 1

(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued


where fcu is the compressive strength of SAP concrete MPafc28d is the 28-day compressive strength of ordinary con-crete MPa x is the SAP content fc

prime is the cylindercompressive strength MPa τmax is the bond strength MPas0 is the slip at ultimate bond strength mm τ is the bond

stress value MPa and s is the slip corresponding to bondstress mm

)e comparison between the theoretical value calculatedaccording to formula (14) and the actual value in the test isshown in Figure 10


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)

Figure 9 Relationship between stress ratio and slip ratio of different SAP contents (a) 0 (b) 01 (c) 02 (d) 03 (e) 08


4 Conclusions

In this paper through relevant tests and theoretical deri-vation the bond behavior of concrete mixed with SAP wassystematically studied and the following conclusions wereobtained

(1) )e compressive strength of HSC mixed with SAPfirst increases and then decreases with the increase ofSAP content )e compressive strength of concretewith SAP content of 0 01 02 03 and 08 is4927 5151 4442 3897 and 3285MPa respectively

(2) With the increase of SAP content the bond strengthof HSC with SAP content first increases and thendecreases )e bond strength of concrete with SAPcontent of 0 01 02 03 and 08 are re-spectively 3676 4004 3456 3141 and 2748MPa

(3) )e bond strength of HSC mixed with SAP increaseswith the increase of its compressive strength and aprediction model of the bond strength of SAPconcrete is established

(4) )e slip corresponding to bond strength of HSCmixed with SAP decreases with the increase ofcompressive strength and the prediction model ofslip corresponding to bond strength of concretemixed with SAP is established

(5) A prediction model of stress-slip relationship be-tween steel bars and HSC mixed with SAP wasestablished which was in good agreement with the

experimental data and could be used to estimate thestress-slip relationship of HSC mixed with differentSAP content

5 Future Work

In this paper compression and bond strength for HSC withvarious SAP content were determined from pull-out tests)e results presented can be utilized for determining theamount of SAP addition in engineering applications Alsothe slip-stress relationship developed in this study can beincorporated into the finite element analysis for structuresIn addition the slip-stress curve was developed for 50MPacompression strength HSC )e reason of not being able toobtain the descending portion after the ultimate bondingstress can be attributed to the high bond strength betweenHSC and the rebar In the future the bond strength fornormal strength concrete should be compared with thisstudy

Data Availability

)e research data used to support the findings of this studyare available from the corresponding author upon request

Conflicts of Interest

)e authors declare that they have no conflicts of interest

0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0

Test data for SAP 01Analytical data for SAP 0



Analytical data for SAP 03Test data for SAP 08Analytical data for SAP 08

Figure 10 )eoretical and practical comparison of bond behavior of concrete mixed with SAP


References

[1] ACI Committee 363 363R-10 Report on High-StrengthConcrete American Concrete Institute Indianapolis INUSA 2010

[2] D Shen M Wang Y Chen W Wang and J ZhangldquoPrediction of internal relative humidity in concrete modifiedwith super absorbent polymers at early agerdquo Construction andBuilding Materials vol 149 pp 543ndash552 2017

[3] D P Bentz M A Peltz and J Winpigler ldquoEarly-Ageproperties of cement-based materials II influence of water-to-cement ratiordquo Journal of Materials in Civil Engineeringvol 21 no 9 pp 512ndash517 2009

[4] D Shen J Jiang W Wang J Shen and G Jiang ldquoTensilecreep and cracking resistance of concrete with different water-to-cement ratios at early agerdquo Construction and BuildingMaterials vol 146 pp 410ndash418 2017

[5] D J Shen K Q Liu Y Ji H F Shi and J Y Zhang ldquoEarly ageresidual stress and stress relaxation of fly ash high-performanceconcreterdquo Magazine of Concrete Research vol 72 no 2 2017

[6] A Bentur S-I Igarashi and K Kovler ldquoPrevention of au-togenous shrinkage in high-strength concrete by internalcuring using wet lightweight aggregatesrdquo Cement and Con-crete Research vol 31 no 11 pp 1587ndash1591 2001

[7] D Shen J Jiang Y Jiao J Shen and G Jiang ldquoEarly-agetensile creep and cracking potential of concrete internallycured with pre-wetted lightweight aggregaterdquo Constructionand Building Materials vol 135 pp 420ndash429 2017

[8] J Liu C Shi XMa K H Khayat J Zhang and DWang ldquoAnoverview on the effect of internal curing on shrinkage of highperformance cement-based materialsrdquo Construction andBuilding Materials vol 146 pp 702ndash712 2017

[9] T J Barrett I De la Varga and W J Weiss ldquoReducingcracking in concrete structures by using internal curing withhigh volumes of fly ashrdquo Structures Congress vol 46pp 699ndash707 2012

[10] X-M Kong Z-L Zhang and Z-C Lu ldquoEffect of pre-soakedsuperabsorbent polymer on shrinkage of high-strength con-creterdquoMaterials and Structures vol 48 no 9 pp 2741ndash27582015

[11] D Shen J Jiang M Zhang P Yao and G Jiang ldquoTensilecreep and cracking potential of high performance concreteinternally cured with super absorbent polymers at early agerdquoConstruction and Building Materials vol 165 pp 451ndash4612018

[12] J Schlitter and T J Barrett ldquoRestrained shrinkage behaviordue to combined autogenous and thermal effects in mortarscontaining super absorbent polymer (SAP)rdquo in Proceedings ofthe International RILEM Conference on Use of SuperabsorbentPolymers and Other New Additives in Concrete pp 233ndash242Lyngby Denmark August 2010

[13] D Shen X Wang D Cheng J Zhang and G Jiang ldquoEffect ofinternal curing with super absorbent polymers on autogenousshrinkage of concrete at early agerdquo Construction and BuildingMaterials vol 106 pp 512ndash522 2016

[14] L Dudziak and V Mechtcherine ldquoEnhancing early-age re-sistance to cracking in high-strength cement-based materialsby means of internal curing using super absorbent polymersAdditions improving properties of concreterdquo RILEM Pro-ceedings Pro vol 77 pp 129ndash139 2010

[15] O M Jensen and P Lura ldquoTechniques and materials forinternal water curing of concreterdquo Materials and Structuresvol 39 no 9 pp 817ndash825 2006

[16] O M Jensen and P F Hansen ldquoWater-entrained cement-basedmaterialsrdquoCement and Concrete Research vol 31 no 4pp 647ndash654 2001


[18] S Monning and P Lura ldquoSuperabsorbent polymersndashan ad-ditive to increase the freeze-thaw resistance of high strengthconcreterdquo in Advances in Construction MaterialsC U Grosse Ed pp 351ndash358 Springer Berlin Germany2007

[19] L Faping and L Jiesheng ldquoStudy on the properties andmechanism of mortars modified by super absorbent poly-mersrdquo Journal of Testing and Evaluation vol 47 no 2pp 1516ndash1532 2019

[20] H AzariJafari A Kazemian M Rahimi and A Yahia ldquoEf-fects of pre-soaked super absorbent polymers on fresh andhardened properties of self-consolidating lightweight con-creterdquo Construction and Building Materials vol 113pp 215ndash220 2016

[21] A Mignon D Snoeck D Schaubroeck et al ldquopH-responsivesuperabsorbent polymers a pathway to self-healing of mor-tarrdquo Reactive and Functional Polymers vol 93 pp 68ndash762015

[22] D Snoeck D Schaubroeck P Dubruel and N De BelieldquoEffect of high amounts of superabsorbent polymers andadditional water on the workability microstructure andstrength of mortars with a water-to-cement ratio of 050rdquoConstruction and Building Materials vol 72 pp 148ndash1572014

[23] S Al-Hubboubi T al-Attar H Al-Badry S AboodR Mohammed and B Haddhood ldquoPerformance of super-absorbent polymer as an internal curing agent for self-compacting concreterdquo MATEC Web of Conferences vol 162Article ID 02023 2018

[24] A J Klemm and K S Sikora ldquo)e effect of superabsorbentpolymers (SAP) on microstructure and mechanical propertiesof fly ash cementitious mortarsfly ash cementitious mortarsrdquoConstruction and Building Materials vol 49 pp 134ndash1432013

[25] X Bian L Zeng Y Deng and X Li ldquo)e role of superab-sorbent polymer on strength andmicrostructure developmentin cemented dredged clay with high water contentrdquo Polymersvol 10 no 10 p 1069 2018

[26] P Lura O M Jensen and S-I Igarashi ldquoExperimental ob-servation of internal water curing of concreterdquo Materials andStructures vol 40 no 2 pp 211ndash220 2007

[27] H Zhu Z Wang J Xu and Q Han ldquoMicroporous structuresand compressive strength of high-performance rubber con-crete with internal curing agentrdquo Construction and BuildingMaterials vol 215 pp 128ndash134 2019

[28] B P Hughes and C Videla ldquoDesign criteria for early-agebond strength in reinforced concreterdquo Materials and Struc-tures vol 25 no 8 pp 445ndash463 1992

[29] R A Chapman and S P Shah ldquoEarly-age bond strength inreinforced concreterdquo ACI Materials Journal vol 84 no 6pp 501ndash510 1988

[30] X Song Y Wu X Gu and C Chen ldquoBond behaviour ofreinforcing steel bars in early age concreterdquo Construction andBuilding Materials vol 94 pp 209ndash217 2015

[31] X L Tang Y H Qin and W J Qu ldquoExperimental study ontime-varying regularity of compressive and bond strength ofconcrete at early-agerdquo Journal of Building Materials andStructures vol 30 no 4 pp 145ndash150 2009


[32] X Fu and D D L Chung ldquoDecrease of the bond strengthbetween steel rebar and concrete with increasing curing age 11Communicated by DM RoyrdquoCement and Concrete Researchvol 28 no 2 pp 167ndash169 1998

[33] C O Orangun J O Jirsa and J E Breen ldquoA revaluation oftest data on development length and splicesrdquo Journal of ACIvol 74 no 3 pp 114ndash122 1977

[34] D Darwin M L )olen E K Idun and J Zuo ldquoSplicestrength of high relative rib area reinforcing barsrdquo AmericanConcrete Institute Structural Journalvol 93 no 1 pp 95ndash1071996

[35] ACI Committee 408 Bond and Development of StraightReinforcing Bars in Tension ACI 408R-03 American ConcreteInstitute Indianapolis IN USA 2003

[36] R Eligehausen E P Popov and V V Bertero Local BondStressndashSlip Relationships of Deformed Bars under GeneralizedExcitations University of California Berkeley CL USA 1983

[37] M R Esfahani and B V Rangan ldquoBond between normalstrength and high strength concrete (HSC) and reinforcingbars in splices in beamsrdquoACI StructuralJournal vol 95 no 3pp 272ndash280 1998

[38] M N S Hadi ldquoBond of high strength concrete with highstrength reinforcing steelsim2008-07-24sim2008-10-28sim2008-11-26simrdquo e Open Civil Engineering Journal vol 2 no 1pp 143ndash147 2008

[39] J Zuo and D Darwin ldquoSplice strength of conventional andhigh relative rib area bars in normal and high-strengthconcreterdquo ACI Structural Journal vol 97 no 4 pp 630ndash6412000

[40] J-Y Lee T-Y Kim T-J Kim et al ldquoInterfacial bond strengthof glass fiber reinforced polymer bars in high-strength con-creterdquo Composites Part B Engineering vol 39 no 2pp 258ndash270 2008

[41] R Okelo and L R Yuan ldquoBond strength of fiber reinforcedpolymer rebars in normal strength concreterdquo Journal ofComposites for Construction vol 9 no 3 pp 203ndash213 2014

[42] D Shen X Shi H Zhang X Duan and G Jiang ldquoExperi-mental study of early-age bond behavior between highstrength concrete and steel bars using a pull-out testrdquo Con-struction and Building Materials vol 113 pp 653ndash663 2016

[43] Comite Euro-International du Beton (CEB-FIP) CEB-FIP ModelCode 2010 in First Completed Draft Comite Euro-Internationaldu Beton Lausanne Switzerland 2010

[44] China Ministry of Construction Chinese Standard GB 50010-2010 Code for Design of Concrete Structures China Ministryof Construction Beijing China 2010

[45] M H Harajli M Hout and W Jalkh ldquoLocal bond stressndashslipbehavior of reinforcing bars embedded in plain and fiberconcreterdquo ACI Materials Journal vol 92 no 4 pp 343ndash3531995

[46] M Harajli B Hamad and K Karam ldquoBond-slip response ofreinforcing bars embedded in plain and fiber concreterdquoJournal of Materials in Civil Engineering vol 14 no 6pp 503ndash511 2002

[47] Y L Xu and W D Shen ldquoExperimental study of bond be-havior of reinforced concreterdquo Journal of Building Materialsand Structures vol 15 no 3 pp 26ndash37 1994

[48] J M Alsiwat and M Saatcioglu ldquoReinforcement anchorageslip under monotonic loadingrdquo Journal of Structural Engi-neering vol 118 no 9 pp 2421ndash2438 1992

[49] E Cosenza G Manfredi and R Reallfonzo ldquoAnalyticalmodeling of bond between FRP reinforcing bars and con-creterdquo in Proceedings of the 2nd International RILEMSYmposium pp 164ndash171 London UK August 1995

[50] B Tighiouart B Benmokrane and D Gao ldquoInvestigation ofbond in concrete member with fibre reinforced polymer(FRP) barsrdquo Construction and Building Materials vol 12no 8 pp 453ndash462 1998

[51] J Y Lee C K Yi Y G Cheong and B I Kim ldquoBond stress-slip behaviour of two common GFRP rebar types with pulloutfailurerdquo Magazine of Concrete Research vol 64 no 7pp 575ndash591 2012

[52] ASTM Standard Specification for Lightweight Aggregate forInternal Curing of Concrete ASTM International WestConshohocken PA USA 2013

[53] RILEMCEBFIP Recommendations on Reinforcement Steelfor Reinforced Concrete CEB News Lausanne Switzerland1983


strength concrete mixed with SAP is still unknown In thispaper an experimental study has been carried out aimed atestablishing SAP content and compressive strength rela-tionship SAP content and HSC bond strength relationshipand the stress-slip model for HSC with SAP

2 Experimental Investigation

21 Material Properties )e cement used in this test is PO425 Portland cement with chemical composition shown inTable 1 Medium coarse sand and 5ndash16mm continuousgraded gravel were mixed with the cement to create concretewith a compression strength of 50MPa High efficiencypolycarboxylate superplasticizer was added as a water re-ducing agent Drying and absorbing states of SAP are shownin Figure 1 Standard structural rebars are 16mm in di-ameter shown in Figure 2 In )eory the internal curingwater should be the same for same water-to-cement ratioHowever when SAP is added water is partially absorbedsuch that more water is needed in addition to that for in-ternal curing)erefore the internal curing water is set to be20 times of the SAP content

)e mixture proportions of concrete used in the test areshown in Table 2

22 Required Internal CuringWater In order to ensure thatthe cement can reach the maximum hydration level theinternal curing water amount can be calculated according tothe following equation [52]

Mic Cf times CS times αmax (1)

where Mic is internal curing water mass required forcomplete hydration of cement Cf is the cement mass (kgm3) CS is the shrinkage of cement when it reaches 100hydration for general cement it is 007 and αmax is themaximum hydration degree when all water in SAP is usedfor cement hydration without evaporation loss generally itis [WC]036 (when WCle 036)

According to the theoretical calculation the internalcuring water amount is 3312 kgm3 but considering thatdifferent SAP contents were designed in the test the finalinternal curing water amount of S0 S1 S2 S3 and S8 wasdetermined to be 0 102 204 306 and 816 kgm3respectively

23 Concrete Preparation for Compressive Strength and Pull-Out Test A total of 6 specimens for pull-out test were madeas shown in Figure 3 )e rebar was embedded centrically inthe 150mmtimes 150mmtimes 150mm concrete cube )e stan-dard 28-day strength of the concrete is 50MPa )e em-bedment length of the rebar in the concrete block is 3 timesof rebar diameter (48mm) )e rebar was sheathed withPVC pipes for debonding on both ends of the concrete blockat a length of 34mm and 68mm respectively A shorterbond length 3 times rebar diameter instead of typically used5 times rebar diameter [53] was adopted in order to obtain acomplete stress-slip curve and prevent splitting

)ree 150mm concrete cubes were set for the com-pressive strength test )e concrete mixing is followed in asequence First of all cement coarse and fine aggregate anddry SAP were put together and mixed for 30 s then half ofthe water and the water reducing agent were added andmixed for another 2min after that the remaining half of thewater and the water reducing agent were poured and mixedfor additional 2min Once the mixing was completed themixture was immediately poured into molds )e specimenshave been cured for 28 days to achieve desirable strength

24 Experimental Process A hydraulic universal testingmachine was used for the test and an LVDT sensor was seton the specimen to measure the relative slip of steel bar andconcrete as shown in Figure 4(a) )e test was controlled bydisplacement and the loading rate was 03mmmin)e testended when the steel bar was pulled out or broken theconcrete specimen was damaged or reaches the specifieddisplacement Dynamic data collection was used to recordthe load value and the reading of the LVDT )e failuremode of all tests is deemed to be split failure from the visualinspection shown in Figure 4(b)

3 Experiment Results

31 Effect of SAP on Compressive Strength of HSC )ecompressive strength of HSCwith different content of SAP isshown in Figure 5 It indicates that a small amount of SAPcan increase the compressive strength of HSC but when thecontent exceeded the peak value the compressive strengthwas reduced When the SAP content was 01 of cementmass the compressive strength of concrete increases by455 when the SAP content was 02 03 and 08 ofcement mass the compressive strength of concrete de-creased by 984 2091 and 3333 respectively )eamount of SAP needed to achieve maximum compressivestrength is a trade-off analysis SAP reduces the shrinkage inconcrete and improves cement hydration which helps in-crease the compressive strength Meanwhile the addition ofSAP increases water diversion and porosity and thereforeresults in decreased compressive strength )is experimentshowed that the peak of compressive strength had beenachieved with 01 SAP addition

)e following equation was created to best fit the datapoints in Figure 5 with the goodness of fit R2 099


2minus 701x + 307

100x2

minus 1193x + 307 (2)

where fcu is the compressive strength of SAP concrete MPafc28 d is the 28-day compressive strength of ordinary con-crete MPa x is the SAP content

)e calculated and measured compressive strength ofSAP concrete are listed in Table 3 It shows that the dif-ferences between the calculated and measured values areminimal so that equation (2) can be adopted to represent theSAP content-compressive relationship



τu Pu

π dld (3)






(a)

(b)









b (4)





a A + Bcmin

db

+ Cdb

ld (5a)

b 05 (5b)






150

150

Concrete

50 300

PVCPVC

500

16


(a) (b)





cmin+ 091113888 1113889 πdbld( 1113857

minus1

(6a)

b 025 (6b)




a 41 (7a)

b 05 (7b)


a 165 (8a)

b 07 (8b)

030

32

34

36

38

40

42

44

46Co

mpr

essiv

e str

engt

h (M

Pa) 48

50

52

54

01 02 03 04 05SAP ()


06 07 08 09











τb 203 fcprime( 111385708

(9)







1113890 1113891

08

(10)



s0 m

fcprime + n

(11)





s0 4874

fcprime + 1679

(12)

00

5

10

15

20

25

30

35

40St

ress

(MPa

)

45

50

55

01 02 03 04 05SAP ()


06 07 08









τ τmaxs

s01113888 1113889

α

(13a)


ττmax

s

s01113888 1113889

α

(13b)




τ τmaxs

s01113888 1113889

01892

(14)



2minus 701x + 307

100x2

minus 1193x + 307 (15a)

fcprime 08fcu (15b)


(15c)

s0 4874

fcprime + 1679

(15d)

τ τmaxs

s01113888 1113889

01892

(15e)

500

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45




35 40 45





2608

085

09

095

1

105

11

s 0 (m

m)

115



38 40 42




1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01



04 05 06 07 08 09 1

(a)

Figure 9 Continued



1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued







1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References

























































τu Pu

π dld (3)






(a)

(b)









b (4)





a A + Bcmin

db

+ Cdb

ld (5a)

b 05 (5b)






150

150

Concrete

50 300

PVCPVC

500

16


(a) (b)





cmin+ 091113888 1113889 πdbld( 1113857

minus1

(6a)

b 025 (6b)




a 41 (7a)

b 05 (7b)


a 165 (8a)

b 07 (8b)

030

32

34

36

38

40

42

44

46Co

mpr

essiv

e str

engt

h (M

Pa) 48

50

52

54

01 02 03 04 05SAP ()


06 07 08 09











τb 203 fcprime( 111385708

(9)







1113890 1113891

08

(10)



s0 m

fcprime + n

(11)





s0 4874

fcprime + 1679

(12)

00

5

10

15

20

25

30

35

40St

ress

(MPa

)

45

50

55

01 02 03 04 05SAP ()


06 07 08









τ τmaxs

s01113888 1113889

α

(13a)


ττmax

s

s01113888 1113889

α

(13b)




τ τmaxs

s01113888 1113889

01892

(14)



2minus 701x + 307

100x2

minus 1193x + 307 (15a)

fcprime 08fcu (15b)


(15c)

s0 4874

fcprime + 1679

(15d)

τ τmaxs

s01113888 1113889

01892

(15e)

500

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45




35 40 45





2608

085

09

095

1

105

11

s 0 (m

m)

115



38 40 42




1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01



04 05 06 07 08 09 1

(a)

Figure 9 Continued



1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued







1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References



























































b (4)





a A + Bcmin

db

+ Cdb

ld (5a)

b 05 (5b)






150

150

Concrete

50 300

PVCPVC

500

16


(a) (b)





cmin+ 091113888 1113889 πdbld( 1113857

minus1

(6a)

b 025 (6b)




a 41 (7a)

b 05 (7b)


a 165 (8a)

b 07 (8b)

030

32

34

36

38

40

42

44

46Co

mpr

essiv

e str

engt

h (M

Pa) 48

50

52

54

01 02 03 04 05SAP ()


06 07 08 09











τb 203 fcprime( 111385708

(9)







1113890 1113891

08

(10)



s0 m

fcprime + n

(11)





s0 4874

fcprime + 1679

(12)

00

5

10

15

20

25

30

35

40St

ress

(MPa

)

45

50

55

01 02 03 04 05SAP ()


06 07 08









τ τmaxs

s01113888 1113889

α

(13a)


ττmax

s

s01113888 1113889

α

(13b)




τ τmaxs

s01113888 1113889

01892

(14)



2minus 701x + 307

100x2

minus 1193x + 307 (15a)

fcprime 08fcu (15b)


(15c)

s0 4874

fcprime + 1679

(15d)

τ τmaxs

s01113888 1113889

01892

(15e)

500

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45




35 40 45





2608

085

09

095

1

105

11

s 0 (m

m)

115



38 40 42




1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01



04 05 06 07 08 09 1

(a)

Figure 9 Continued



1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued







1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References


























































cmin+ 091113888 1113889 πdbld( 1113857

minus1

(6a)

b 025 (6b)




a 41 (7a)

b 05 (7b)


a 165 (8a)

b 07 (8b)

030

32

34

36

38

40

42

44

46Co

mpr

essiv

e str

engt

h (M

Pa) 48

50

52

54

01 02 03 04 05SAP ()


06 07 08 09











τb 203 fcprime( 111385708

(9)







1113890 1113891

08

(10)



s0 m

fcprime + n

(11)





s0 4874

fcprime + 1679

(12)

00

5

10

15

20

25

30

35

40St

ress

(MPa

)

45

50

55

01 02 03 04 05SAP ()


06 07 08









τ τmaxs

s01113888 1113889

α

(13a)


ττmax

s

s01113888 1113889

α

(13b)




τ τmaxs

s01113888 1113889

01892

(14)



2minus 701x + 307

100x2

minus 1193x + 307 (15a)

fcprime 08fcu (15b)


(15c)

s0 4874

fcprime + 1679

(15d)

τ τmaxs

s01113888 1113889

01892

(15e)

500

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45




35 40 45





2608

085

09

095

1

105

11

s 0 (m

m)

115



38 40 42




1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01



04 05 06 07 08 09 1

(a)

Figure 9 Continued



1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued







1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References




























































τb 203 fcprime( 111385708

(9)







1113890 1113891

08

(10)



s0 m

fcprime + n

(11)





s0 4874

fcprime + 1679

(12)

00

5

10

15

20

25

30

35

40St

ress

(MPa

)

45

50

55

01 02 03 04 05SAP ()


06 07 08









τ τmaxs

s01113888 1113889

α

(13a)


ττmax

s

s01113888 1113889

α

(13b)




τ τmaxs

s01113888 1113889

01892

(14)



2minus 701x + 307

100x2

minus 1193x + 307 (15a)

fcprime 08fcu (15b)


(15c)

s0 4874

fcprime + 1679

(15d)

τ τmaxs

s01113888 1113889

01892

(15e)

500

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45




35 40 45





2608

085

09

095

1

105

11

s 0 (m

m)

115



38 40 42




1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01



04 05 06 07 08 09 1

(a)

Figure 9 Continued



1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued







1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References


























































τ τmaxs

s01113888 1113889

α

(13a)


ττmax

s

s01113888 1113889

α

(13b)




τ τmaxs

s01113888 1113889

01892

(14)



2minus 701x + 307

100x2

minus 1193x + 307 (15a)

fcprime 08fcu (15b)


(15c)

s0 4874

fcprime + 1679

(15d)

τ τmaxs

s01113888 1113889

01892

(15e)

500

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45




35 40 45





2608

085

09

095

1

105

11

s 0 (m

m)

115



38 40 42




1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01



04 05 06 07 08 09 1

(a)

Figure 9 Continued



1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued







1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References
























































2608

085

09

095

1

105

11

s 0 (m

m)

115



38 40 42




1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01



04 05 06 07 08 09 1

(a)

Figure 9 Continued



1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued







1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References

























































1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(b)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(c)

Figure 9 Continued







1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References





























































1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(d)


1

09

08

07

06

05

Slip

ratio

04

03

02

01

00 01 02 03


(e)



4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







References
























































4 Conclusions








5 Future Work


Data Availability




0200

5

10

15

20

25

35

40

30Bo

nd st

ress

(MPa

)

45

04 06 08Slip (mm)

1 12

Test data for SAP 0







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effect of internal curing with superabsorbent polymers on

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