Materials and Design 46 (2013) 609–616

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Materials and Design

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Technical Report

Behaviour of self compacting concrete using Portland pozzolana cement withdifferent levels of fly ash

P. Dinakar ⇑, M. Kartik Reddy, Mudit SharmaSchool of Infrastructure, Indian Institute of Technology, Bhubaneswar 751 013, India

a r t i c l e i n f o

Article history:Received 22 August 2012Accepted 9 November 2012Available online 23 November 2012

0261-3069/$ - see front matter � 2012 Elsevier Ltd. Ahttp://dx.doi.org/10.1016/j.matdes.2012.11.015

⇑ Corresponding author. Tel.: +91 674 2306353.E-mail addresses: pdinakar@iitbbs.ac.in, pdinakar@

kartik@iitbbs.ac.in (M. Kartik Reddy), mudit@iitbbs.ac

a b s t r a c t

The influence of including fly ash (FA) on the properties of self-compacting concrete (SCC) is investigated.Portland pozzolana cement (PPC) was partially replaced with 10–70% fly ash. The water to binder ratiowas maintained constant at 0.30 for all mixes. Properties included were self-compactibility properties(slump flow, V-funnel time and L-box blocking ratio) mechanical properties (compressive strength, split-ting tensile strength and elastic modulus), and durability properties (water absorption, water penetrationdepth and chloride permeability). The results indicate that fly ash along with PPC can be used in SCC toproduce high strength high performance concretes. Replacing 30% of PPC with FA resulted in strength ofnearly 100 MPa at 56 days. Splitting tensile strength and elastic modulus values have also followed thesame trend. High absorption values were obtained with increasing amount of FA, however, all the SCCsexhibited initial absorption values of less than 3%. The water penetration depths in SCCs were lower at10% and 30% replacements of fly ash but remained higher at 50% and 70% replacements. There is a sys-tematic reduction in the chloride permeability of SCCs at 30% replacement of fly ash.

� 2012 Elsevier Ltd. All rights reserved.

1. Introduction

Self Compacting Concretes (SCCs) require high flowabilitythrough a superplasticiser, and to remain cohesive during handlingoperations special attention is needed in terms of the sand andpaste content apart from a viscosity-modifying admixture to en-hance stability [1]. It is well established earlier that the use of min-eral admixtures such as fly ash and blast furnace slag couldincrease the slump of the concrete mixture without increasing itscost, while reducing the dosage of superplasticiser needed to ob-tain similar slump flow compared to concrete made with Portlandcement only [2]. Also, the use of fly ash improves rheological prop-erties and reduces the cracking potential of concrete as it lowersthe heat of hydration of the cement [3]. It was proved from earlierstudies that up to replacement of 30% fly ash results in a significantimprovement of the rheological properties of flowing concretes[4,5]. The use of fly ash reduces the demand for cement, fine fillersand sand [6], which are required in high quantities in SCC. More-over, the incorporation of fly ash also reduces the need for viscos-ity-enhancing chemical admixtures [7].

High-volume fly ash (HVFA) concretes at about 60% cementreplacement have been reported to achieve excellent mechanicaland durability properties [8]. There are no studies reported on

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the production of SCC when PPC was used with additional replace-ment of fly ash. Bouzoubaa and Lachemi [9] reported on the pro-duction of HVFA–SCC that was flowable, cohesive, and developeda 28-day compressive strength of about 35 MPa. Researchers alsoattempted to produce high-volume fly ash SCCs by replacing upto 70% of Portland cement with class F fly ash [10–12]. Coal bottomash has also been successfully used as sand replacement in thedevelopment of self compacting concrete [13]. Fly ash in high vol-umes in SCCs also improved the durability and corrosion propertiesstudied [10,11,14]. In order to extend the general concept of HVFAconcrete and its applications to a wider range of infrastructure con-struction, this paper outlines the results of a research projectaimed at producing and evaluating the behavoiur of SCCs incorpo-rating high volumes of class F fly ash when Portland pozzolanacement (PPC) was used.

2. Research significance

The approach of manufacturing of SCC was recently modifiedand developed to produce SCC with high performance and high-strength characteristics [15–17]. However, all previous effortsand attempts in the field of SCC were concerned with OrdinaryPortland cement (OPC) and mineral blends such as fly ash, slagand limestone powder, there is a lack of knowledge regarding theutilisation of Portland pozzolana cement (PPC) with mineral blendsin the development of SCC. Generally, there is a great interest andtendency between researchers and concrete technologists to

Table 2Details of the mix proportions in kg/m3.

Constituent SCC10 SCC30 SCC50 SCC70

Cement 495 385 275 165Water 165 165 165 165Fine aggregate 836 818 800 78320 mm 382 374 366 35712.5 mm 525 514 503 491Fly ash 55 165 275 385HRWR 6.6 7.15 7.15 8.80VMA 0.55 1.10 1.10 2.75

610 P. Dinakar et al. / Materials and Design 46 (2013) 609–616

develop concretes by multi-unique characteristics, which wouldnot be attained in traditional NWC. With the growth of buildingactivities in India there is severe cement crisis to meet the de-mands of the construction industry. To meet the demands now adays almost all the major cement manufacturers are producingblended cements consisting of Portland pozzolana cement (PPC)and Portland slag cement (PSC) where PPC has a significant pres-ence in the Indian market as far as the production and usage is con-cerned. Now there is an urgent need to design concretes usingthese blended cements to address the demands of the constructionindustry. Therefore, an attempt was carried out herein to investi-gate the effect of fly ash replacements on the properties of SCCwhen PPC was used.

3. Experimental studies

3.1. Materials

The following materials were employed:

� The cement used in all mixture was Portland pozzolana cement(PPC) conforming to IS 1489 Part 1 [18]. The percentage blend-ing of fly ash in PPC is 28%. In addition fly ash was also used as amineral additive. Their chemical composition is specified inTable 1.� Good quality aggregates have been procured for this investiga-

tion. Crushed granite with nominal grain size of 20 mm andwell-graded river sand of maximum size 4.75 mm were usedas coarse and fine aggregates, respectively. The specific gravitiesof aggregates were determined experimentally. The coarseaggregates with 20, 12.5 mm fractions had specific gravities of2.91 and 2.80, whereas the fine aggregate had specific gravityof 2.73, respectively.� Commercially available poly carboxylate ether (PCE) – based

super-plasticizer (SP) was used in all the concrete mixtures. Itis an F-type high-range water reducer, in conformity withASTM: C 494.

3.2. Mixture proportions

Four SCC mixtures were designed in order to obtain differentfresh-state properties. The details of the mixes for the study are pre-sented in Table 2. Four different mixes (SCC10, SCC30, SCC50 andSCC70) were employed to examine the influence of fly ash in SCCson the fresh, mechanical and durability properties when PPC ce-ment was used. The water–binder ratio for all the mixes was keptconstant at 0.30. In mixes SCC10, SCC30, SCC50 and SCC70 cementcontent was replaced with 10%, 30%, 50% and 70% fly ash (by mass)

Table 1Chemical composition and physical properties of the Portland pozzolana cement(PPC) and fly ash.

Chemical composition PPC Fly ash

CaO 45.7 1.7SiO2 39.1 62.5Al2O3 10.3 26.2Fe2O3 5.82 4.2MgO 1.79 0.8SO3 2.28 0.2Na2O 0.14 0.12K2O 0.71 1.14Loss in ignition 1.72 1.0

Physical propertiesSpecific gravity 3.0 2.2Blaines fineness (m2/kg) 406 350Blending of fly ash in PPC 28 –

respectively. The essential component of SCC is a high range waterreducer (HRWRA) which is also known as superplasticizer. SCCmixtures always include a high-range water-reducing admixture(HRWRA) to ensure concrete is able to flow under its own mass[19]. Several trial mixes were conducted to determine the optimumdosage of superplasticiser for each of the mixtures in order toachieve the required self compacting properties as per EFNARCstandards. The dosage of superplasticiser for each mix was carefullyselected as over dosage may induce bleeding and strength retarda-tion. As far as the aggregate grading is concerned, in the presentinvestigation a combined aggregate grading as recommended bythe DIN 1045 [20] standards was utilised. The aggregates 20, 12.5and 4.75 mm were combined in such a way, so that it meets nearlythe combined grading specification of DIN ‘B’ curve. The percentagefractions of aggregates used for 20 mm – 21%, 12.5 mm – 30% and4.75 mm – 49% of the total aggregate content respectively. Blendingaggregates in this fashion will result in high strength cohesive selfcompacting concretes [12]. Effect of coarse aggregate blending with20 mm and 10 mm on the short-term mechanical properties of SCChas also been carried out earlier [21].

3.3. Mixing and casting details

All the materials were mixed using a pan mixer with a maxi-mum capacity of 80litres. The materials were fed into the mixerin the order of coarse aggregate, PPC, fly ash and sand. The materi-als were mixed dry for 1.5 min. Subsequently three-quarters of thewater was added, followed by the superplasticiser and the remain-ing water while mixing continued for a further 6 min in order toobtain a homogenous mixture. Upon discharging from the mixer,the self compactibility tests were conducted on the fresh proper-ties for each mixture. The fresh concrete was placed into the steelcube moulds and compacted without any vibration. Finally, surfacefinishing was done carefully to obtain a uniform smooth surface.

3.4. Fresh concrete tests

For determining the self-compactibility properties (slump flow,T50 time, V-funnel flow time, L-box blocking ratio) tests were per-formed on all the mixtures. The order of testing was:

(a) Slump flow test and measurement of T50 time.(b) V-funnel flow test.(c) L-box blocking test, respectively. The tests were performed

in accordance with EFNARC [22] standards.

3.5. Specimens and curing

The following specimens were cast from each mixture:

� Three 100 � 100 � 100 mm cubes for the compressive strength.� Three 100 � 200 mm cylinders for the splitting tensile test.� Three 150 � 300 mm cylinders for the modulus of elasticity

test.

Fig. 2. Permeability test set up for determining the water penetration depth.

Fig. 3. Water penetration dept front marked after the test.

P. Dinakar et al. / Materials and Design 46 (2013) 609–616 611

� Two 100 � 100 � 100 mm cubes for water absorption study.� Three 150 � 150 � 150 mm cubes for the water penetration

depth test.� Two 100 � 200 mm cylinders for the rapid chloride penetrabil-

ity test. Samples of 100 � 50 mm were prepared from thesecylinders

After casting, all the specimens were covered with plastic sheetsand water saturated burlap, and left at room temperature for 24 h.The specimens were demoulded after 24 h of casting and werethen cured in water at approximately 27 �C until the testing day.

3.6. Test procedures

The unconfined compressive strength was obtained, at a loadingrate of 2.5 kN/s at the age of 3, 7, 28 and 90 days on 3000 kN ma-chine. The average compressive strength of three specimens wasconsidered for each age. The split tensile strength was also testedon the same machine at the age of 28 and 56 days.

The elastic modulus was determined at the age of 28 and56 days. The specimens were fixed with a longitudinal compress-ometer, placed vertically between the platens of the compressiontesting machine and tested as shown in Fig. 1. This test conformsto ASTM: C 469 for static modulus of elasticity of concrete in com-pression. All the specimens were tested on saturated surface drycondition.

The water penetration depths under pressure were performedon 150 mm cubes as per EN 12390-8 [23] at 28 and 56 days. The testmethod involves the study of water penetration on 15 cm cubesover a 5 bar pressure for a period of 72 h. The experimental setupused for this study was shown in Fig. 2. After the test the specimenswere split exactly into two halves and the water penetration frontwas marked on the specimen as shown in Fig. 3. The maximumdepth of penetration under the test area was determined using ver-nier caliper and recorded it to the nearest millimetre.

The absorption test was carried out on two 100 mm cubes asper ASTM: C 642 at 28 days of water curing. Saturated surfacedry cubes were kept in a hot air oven at 100–110 �C till a constantweight was attained. These are then immersed in water and theweight gain was measured at regular intervals until a constantweight is reached. The absorption at 30 min (initial surface absorp-tion) and final absorption (at a point when the difference betweentwo consecutive weights at 12 h interval was almost negligible) isreported to assess the concrete quality. The final absorption in allcases is observed to be at 72 h.

The rapid chloride penetrability test was conducted in accor-dance with ASTM: C 1202. These were also determined at 28 and

Fig. 1. Test set up for determining the elastic modulus.

56 days. This test measures the ease with which concrete allowsthe charge to pass through and gives an indication of the concreteresistance to chloride-ion penetration. Two specimens of 100 mmin diameter and 50 mm in thickness conditioned according to thestandard were subjected to 60 V potential for 6 h. The total chargethat passed through the concrete specimens was determined andused to evaluate the chloride penetrability of each concrete mix-ture. The reported results evaluated by the Coulomb charge arethe average of two tests.

4. Test results and discussion

4.1. Fresh properties

4.1.1. HRWR and VMA demandTable 3 presents the demand of HRWR and VMA admixtures

used in all SCC mixtures. It can be seen that the addition of flyash in Portland pozzolana cement has a significant influence onthe flow characteristics of SCC. It can be observed that as the flyash content increases the demand for HRWR and VMA also in-creases. For 70% replacement SCC demanded 1.6% and 0.5% ofHRWR and VMA. The reason could be that at 70% replacementthere was an abnormal increase in the paste volume of the SCC,this high paste volume is due to the low specific gravities of PPCand fly ash. Also the PPC used in this investigation has got a veryhigh fineness of 406 m2/kg. For 70% replacement several trailswere conducted to optimise the HRWR and VMA dosages. Initiallyat low VMA dosage of around 0.2% the concretes seems to be cohe-

Table 3Fresh properties of the concrete investigated.

Concretename

Plasticdensity (kg/m3)

T50 (s) Slumpflow (mm)

V-funnelflow time (s)

L-boxblocking ratio

SCC10 2432 6 620 28.19 0.77SCC30 2399 5 685 16.0 0.80SCC50 2390 5 705 20.39 0.93SCC70 2332 7 670 28.16 0.83

5.5 6.0 6.5 7.0 7.5 8.0 8.5T50 (sec)

15

18

21

24

27

30

V-fu

nnel

flow

tim

e (s

ec)

Vft = 0.89xT501.70

R2 = 0.74

Fig. 5. Relationship between V-funnel flow time and T50.

612 P. Dinakar et al. / Materials and Design 46 (2013) 609–616

sive exhibiting a very good slump flow around 700 mm, but afterfew minutes significant amount of bleeding is noticed and theaggregates settlement was seen in the cube moulds. This promptedto use more amount of VMA to avoid segregation and bleeding.VMA dosage of 0.5% for the 70% replacement is quite high com-pared to earlier studies published in the literature. In spite of usinghigh amount of VMA still a very small amount of bleeding is ob-served in the mix. The results are quite contrary to the earlier re-sults published, where good flowability and cohesive SCCs havebeing developed at 70% replacement of fly ash with OPC cement[10,11,14,24]. From the results it can be concluded that whenPPC was used in the development of SCC, fly ash replacements ofthe order 30–50% will be ideal.

4.1.2. Fresh concrete test resultsFig. 4 presents the slump flow with respect to fly ash dosage.

From the results it can be seen that as the fly ash dosage increasesthe slump flow also increases up to 50% and after that there wasdrop in the flow at 70% replacement. The four mixtures exhibitedslump flow values between 620 and 705 mm showing the capabil-ity of concrete to deform under its own weight. Slump flow of650 ± 50 mm is required for SCC [22], and all the concretes devel-oped here have satisfied the requirements. The 10% replacementexhibited a thixotropic behaviour showing a slump flow value of620 mm, whereas the 30% and 50% replacements exhibited valuesbetween 680 and 700 mm.

Also, the T50s for all mixtures did not show significant variation.On the other hand, SCC mixtures with fly ash percentages of 30%and 50% showed equal values of 6 s, whereas the 10% and 70%replacements showed values of 7 and 8 s. The V-funnel flow timesalso exhibited a similar behaviour. V-funnel measurements ofsome mixtures exceeded the upper limit; however, all concretemixtures filled the moulds by its own weight without the needfor vibration. Many researchers have used both the T50 andV-funnel times as indicators of viscosity of highly flowable con-crete mixes. The relationship between these results is presentedin Fig. 5. This figure shows that there is an acceptable relationship(R2 = 0.74) between T50 and V-funnel times for these SCC mixtures.

0 10 20 30 40 50 60 70 80Fly ash (%)

600

620

640

660

680

700

720

Slum

p flo

w (m

m)

Fig. 4. Variation of slump flow with respect to fly ash replacement.

Experimental measurements related with L-box ratio indicatethe filling and passing ability of each mixture. L-box test is moresensitive to blocking. The determined L-box ratios of four mixtureswith respect to the fly ash dosages are presented in Fig. 6. It can beseen that as the fly ash percentage increases from 30% to 70% SCCmixtures exhibited values greater than 0.8, whereas the 10%replacement SCC because of its thixotropic behaviour exhibited va-lue less than 0.8, but still maintaining the self compactability. Inthe same figure the variation of V-funnel flow times with respectto fly ash dosages is also presented. It can be observed that flyash replacements of around 30–50% will be ideal for developingSCCs when Portland pozzolana cement is used.

4.2. Hardened concrete tests

After outlining the performance of SCCs during its fresh state, itis necessary to understand the performance of these concretes dur-ing its hardened state. In this study, the mechanical properties ofall the SCCs were investigated through compressive strengths,splitting tensile strengths and modulus of elasticity. Compressivestrength tests were carried out at 3, 7, 28 and 56 days and the re-sults are presented in Table 4. Fig. 7 shows the variation of com-pressive strengths at 28 and 56 days with respect to the fly ashreplacement. As noted from the results shown in Fig. 7, the com-pressive strength, of SCC increased drastically from 10% to 30%replacement of fly ash but started to decline at 50% and 70%replacement. High compressive strength of nearly 100 MPa hasbeen obtained at 30% replacement at 56 days than the other flyash mixes including the 10% replacement, where a high strength

0 10 20 30 40 50 60 70 80Fly ash (%)

0.7

0.8

0.9

1.0

Blo

ckin

g ra

tio

0

5

10

15

20

25

30

V-Funnel flow tim

e (sec)

Blocking ratio Vs Fly ash dosage

V funnel flow time Vs Fly ash dosage

Fig. 6. Effect of fly ash replacement on blocking ratio and V-funnel flow time.

Table 4Mechanical properties of the concretes investigated.

Concrete name Compressive strength (MPa) Splitting tensile strength (MPa) Modulus of elasticity (GPa)

3 day 7 day 28 day 56 day 28 day 56 day 28 day 56 day

SCC10 44.42 58.37 78.97 87.85 5.62 5.55 43.24 42.14SCC30 48.33 51.20 88.06 99.43 5.93 6.06 45.42 46.24SCC50 27.1 35.91 60.83 66.20 4.12 4.20 36.63 36.01SCC70 18.14 21.77 44.21 50.21 2.61 2.84 31.56 32.78

0 10 20 30 40 50 60 70 80Fly ash (%)

30

40

50

60

70

80

90

100

110

Com

pres

sive

str

engt

h (M

Pa)

28 day

56 day

Fig. 7. Variation of compressive strength with respect to fly ash replacement.

40 50 60 70 80 9028 day compressive strength (MPa)

25

30

35

40

45

50

28 d

ay E

last

ic m

odul

us (G

Pa)

ACI model

BIS model

Experimental

Fig. 8. Relationship between compressive strength and modulus of elasticity.

P. Dinakar et al. / Materials and Design 46 (2013) 609–616 613

of approximately 88 MPa at 56 days is obtained. Generally and atthe same water to binder ratio, there is a strength reduction forconcretes containing fly ash compared with that of the control.However, and even at high fly ash content (70%), a long-term highstrength of about 50 MPa is achieved at the same water to binderratio. Higher strength would be expected in the fly ash mixes ifthe w/b ratio was lowered to achieve similar workability to thatof the control. The trend is similar to results obtained elsewhereon SCC containing fly ash [25].

Modulus of elasticity of concrete is mainly related with its com-pressive strength. It is well known fact that normal weight aggre-gate has a higher modulus of elasticity than hydrated cementpaste, a higher content of a given aggregate results in a highermodulus of elasticity of concrete of a given compressive strength.There are many expressions for traditional concrete, in order topredict the modulus of elasticity which is mainly related to com-pressive strength and density of concrete [26,27]. Since SCC beinga different material, it may exhibit different stress–strain behav-iour relationship since SCC mixtures have a lower amount of coarseaggregate, more powder content and the use of mineral admix-tures such as fly ash or slag. Various studies on modulus of elastic-ity of SCC resulted with conflicting conclusions. It was wellestablished that the elastic modulus of SCC performed almost sim-ilarly with that of the traditional concrete when the strength washeld constant [28–30]. On the other hand, it was also proved byan experimental study made earlier that the elastic modulus ofSCC is lower than the traditional concrete [31]. It was also observedthat for a given strength the modulus of elasticity of SCC is lowerthan that of a common concrete [32]. This is due to the smallermaximum grain size of SCC and the higher amount of cement pasteof SCC. From these investigations it may be concluded that it is noteasy to compare the modulus of elasticity with traditional con-crete. These contradictory results may possibly be explained bythe fact that the constituents and rheological behaviour of SCCsare quite different from the traditional concrete. Neither aggregatecontent and maximum size nor cement paste properties are thesame.

In the present investigation the elastic modulus (E) values ob-tained with respect to various fly ash contents are presented in Ta-ble 4. The relationship between compressive strength (fck) andmodulus of elasticity of SCC mixtures is presented in Fig. 8; addi-tionally the relationships of ACI and BIS models have also beenshown in the same figure. As can be seen from the figure SCC mix-tures had exhibited lower elastic moduli when compared with BISmodel ðE ¼ 5

ffiffiffiffiffifck

pÞ and comparable values with ACI model

ðE ¼ 4:73ffiffiffiffiffifck

pÞ. This general tendency of SCC mixtures can be

attributed to the lower amount of coarse aggregate and increasedpaste content. The relationship between the compressive strength(fck) and modulus of elasticity (E) for the tested mixtures has beendetermined by the following equation:

E ¼ 4:78ffiffiffiffiffifck

p; R2 ¼ 0:98 ð1Þ

The variability of these values with different SCC’s can be attrib-uted to two reasons. First the strength grade of tested SCC’s is notthe same. Second the powder ingredients of SCC are different fordifferent fly ash replacements. The reactivity or inert nature of fil-ler may change the strength characteristics and stress–strain rela-tions of mixtures. If individual modulus values of the mixtures areconsidered, it can be seen that similar to compressive strength theelastic modulus of SCC30 at 30% replacement had exhibited thehighest modulus both at 28 and 56 days.

The results of split tensile strength tests at 28 and 56 days arepresented in Table 4. Each value in Table 4 represents the averagesplit tensile strength results of three specimens. The split tensilestrength ranges from 2.61 to 5.93 MPa and 2.84 to 6.06 MPa at28 and 56 days, respectively. The split tensile strength of all SCCmixtures increased with age. The results showed that, an increasein the FA content decreased the split tensile strength of the SCCespecially at 28 days. SCC mixtures containing 10–30% FA replace-ment showed higher split tensile strength than SCC mixtures con-taining 50–70% FA replacement. This indicates that up to a 30% ofFA replacement may have positive effects on the interfacial bondbetween the paste and aggregates. The mixtures containing 50–70% FA showed lower tensile strength probably due to the weaker

40 50 60 70 80 9028 day compressive strength (MPa)

2

3

4

5

6

7

28 d

ay s

plitt

ing

tens

ile s

tren

gth

(MPa

)

fsp = 0.0264fck1.21919

R2 = 0.98

Fig. 9. Relationship between compressive strength and splitting tensile strength.

614 P. Dinakar et al. / Materials and Design 46 (2013) 609–616

bond between the matrix and the aggregates. The relationship be-tween the splitting tensile strength (fsp) and compressive strength(fck) for the SCC mixtures is presented in Fig. 9. For the tested mix-tures the tensile strength can be calculated by using the followingequation:

Fsp ¼ 0:0264f 1:21919ck ð2Þ

Sonebi and Bartos [33] found that splitting tensile strength ofSCC at 28 days is higher than that of traditional concrete. But thestrength grades of SCC and traditional concrete at 28 days are dif-ferent. The results derived from Fig. 8 showed that the splittingtensile strength of SCC mixtures is usually higher due to betterhomogeneity coming from vibration free production.

4.3. Water absorption

The results of water absorption in 30 min (initial surfaceabsorption) as well as the absorption after 72 h (final absorption)for all the concretes are presented in Table 5. From these resultsit can be seen that as the fly ash replacement increases the absorp-tion also increases. Fig. 10 presents the values of 30 min (initial)absorption and final absorption of all the concretes obtained at28 days. The initial absorption and the final absorption values ofall the self compacting fly ash concretes increased with an increasein percentage of fly ash replacement. Fig. 10 also presents the rec-ommendations given by Concrete Society (CEB, 1989) for absorp-tion 30 min [34]. This shows that all the self compacting fly ashconcretes had lower absorption than the limit specified for ‘‘good’’concretes. The absorption values decreases from 28 to 56 days asshown in Table 5. The absorption of the mix with 70% fly ash ishigher at 28 days due to the low amounts of hydration productsproduced. Curing has a significant influence on the pore structureof the concrete, the longer the curing time, more finer the porestructure and the capillary pores are less interconnected and more-over, the porous paste/aggregate interface zone formed at earlyages is densified by continuous curing in water [35]. As morehydration products are produced at 56 days, the absorption of SCCs

Table 5Durability properties of the concretes investigated.

Concrete name Absorption (28 day) (%) Absorption (56 day) (%)

Initial (30 min) Final (72 h) Initial (30 min) Final (

SCC10 0.89 3.54 0.84 3.14SCC30 1.00 4.53 0.95 3.74SCC50 1.29 5.55 1.18 4.95SCC70 1.49 12.12 1.32 10.52

at 56 days is relatively less than that at 28 days. This is similar tosome results on NVC [36].

The final absorption at the end of 72 h also followed a similartrend. SCC70 showed the highest absorption than any other SCC.This may be due to the very high amount of fly ash (70%) in the sys-tem. Except SCC70, the final absorption values of all the other SCCswere similar, the final absorption values of SCCs lie in the range3.54–5.55%. Water absorption is mainly influenced by the pastephase; primarily, it is dependent on the extent of interconnectedcapillary porosity in the paste. Concrete mixes with higher pastecontents are bound to have higher absorption values than con-cretes with lower paste content (at consistent w/b ratio). The lowerwater absorption thus observed for lower fly ash replacements isattributed to the relatively lower paste volume, i.e., smaller capil-lary pore volume. It is noted that self compacting concretes withhigh fly ash replacements have exhibited higher water absorption[10]. The increase in paste volume due to the lower specific gravityof fly ash and PPC contributes to an increased capillary pore vol-ume and increased water absorption. This is clearly reflected inSCC70.

4.4. Water penetration depth

One of the main factors of concrete durability is permeability.Concrete with lower permeability shows better resistance againstchemical attacks. When water penetrates into the concrete, somesoluble salts including chloride ions penetrate into concrete andcause corrosion. Generally, it seems that lower permeability causeshigher durability in concretes [37]. Water penetration test wasused to evaluate the permeability of concretes and validity of thesetests has been approved [23]. Fig. 11 shows the results of the waterpenetration depths of all the SCC mixtures. Similar to absorptionthe penetration depths increases as the fly ash increases not verysignificantly up to 50% replacement whereas significant increasein the penetration depth was noticed in 70% replacement. Thetrend is the same both at 28 and 56 days.

4.5. Chloride permeability

The results of the rapid chloride test measured at 28 and56 days are presented in Fig. 12. The assessment criteria given byASTM 1202 is also given in the same figure. From the results itcan be seen that the Coulomb charge for the SCC70 is higher thanthose of the other SCCs. For SCC70, the Coulomb charge is 3520indicating a rather poor chloride penetration characteristic. It iswell established that the incorporation of fly ash results in drasticreductions in the Coulomb charges. The effect of FA on the chlorideion penetration of concretes was also studied by other researchers.For example, Shi states that the use of supplementary cementingmaterials such as FA may have a significant effect on the chloridemigration of concrete as measured by the RCPT test [38]. This istrue in the case of other replacements other than 70%.

Curing has a significant influence on the permeation propertiesof the concretes. At 28 days SCC10, SCC30, SCC50 and SCC70showed 1812, 923, 1312, 3520 coulombs, whereas at 56 days thesewere reduced to 1188, 692, 823 and 1876 coulombs. At high

Water penetration (mm) Chloride permeability (Coulombs)

72 h) 28 day 56 day 28 day 56 day

5 4 1812 11885 3 923 692

11 9 1312 82335 24 3520 1876

0 10 20 30 40 50 60 70 80Fly ash (%)

0123456789

1011121314

Wat

er a

bsor

ptio

n (%

)

Initial absorption (30 min)

Final absorption

Fig. 10. Relationship between water absorption and fly ash replacement.

0 10 20 30 40 50 60 70 80Fly ash (%)

0

4

8

12

16

20

24

28

32

36

40

Wat

er p

enet

ratio

n de

pth

(mm

)

28 day

56 day

Fig. 11. Relationship between water penetration depth and fly ash replacement.

0

500

1000

1500

2000

2500

3000

3500

Tota

l cha

rge

(cou

lom

bs)

ASTM C 1202 > 4000 ------ High2000 - 4000 ------ Moderate1000 - 2000 ------ Low100 - 1000 ------ Very low

Very low

Low

SCC10 SCC30 SCC50 SCC70

28 day

56 day

Fig. 12. Chloride permeability values of the concretes.

P. Dinakar et al. / Materials and Design 46 (2013) 609–616 615

replacements fly ash has a significant influence on the chloridepenetration characteristics, 30% and 50% replacements have exhib-ited similar behaviour. This may be due to the pore refinement ofthe fly ash at high replacements in addition to the fly ash porerefinement in PPC. The reason for the lower chloride ion penetra-tion of concrete with FA may be attributed to the presence of flyash. The use of fly ash probably resulted in a denser matrix, byreducing the pore size and thickness of transition zone betweenaggregate and surrounding cementitious matrix [39,40]. It shouldalso be noted that the RCPT results depends on the electrical con-ductivity of pore solution, which is determined by the compositionof the pore solution. The electrical conductivity or RCPT value of a

concrete can be reduced by lowering the alkalinity of concrete poresolution. When FA (especially with low-lime and low alkali con-tents) is used to partially replace PC, the concentration of alkaliions and associated hydroxyl ions in the pore solution decreasessignificantly, and the extent of this reduction depends also on FAreplacement level [41]. Because of the expected differences in elec-trical resistance between the SCC mixtures, however, the electricalconductivity values may also be different. As a result, the RCPT val-ues may reflect this difference and therefore should be interpretedwith care. The reason for high chloride penetration in the case of70% replacement is due to the porous nature of the concrete. 70%replacement SCC demanded more amount of superplasticizer andVMA dosage compared to any other SCC developed. This resultedin more air entrainment of the mix developed finally making theSCC porous in nature. This is clearly reflected on the other durabil-ity parameters also discussed above.

5. Conclusions

This study discusses an experimental program carried out toinvestigate the effects of incorporating high volume fly ashreplacement on the flow characteristics of SCC when PPC was usedin the fresh state, and mechanical and durability properties in thehardened state. The following conclusions can be drawn accordingto the results of this study:

1. It can be observed that fly ash replacements of around 30–50%will be ideal for developing SCCs when Portland pozzolanacement was used.

2. High percentage of fly ash (more than 50%) cannot be used toproduce SCC when PPC was used, and 30% replacement of flyash exhibited the highest compressive strength, splitting tensilestrength and elastic modulus. At 30% fly ash as PPC replacementcan produce SCC with a very high compressive strength of100 MPa.

3. Although the absorption increases with increasing fly ash con-tent, the initial absorption values of all SCCs were below 3%.SCC with 70% replacement of fly ash exhibited the highest waterabsorption. Water penetration depth also exhibited similarbehaviour.

4. Increasing amounts of fly ash in SCC reduces the chloride per-meation and 30% replacement exhibited the highest chloridepenetration resistance.

5. Thus, the optimum fly ash percentage was 30% which resultedin highest compressive strength and less chloride permeation.

References

[1] Khayat KH, Guizani Z. Use of viscosity-modifying admixture to enhancestability of fluid concrete. ACI Mater J 1997;94(4):332–41.

[2] Yahia A, Tanimura M, Shimabukuro A, Shimoyama Y. Effect of rheologicalparameters on self compactability of concrete containing various mineraladmixtures. In: Proceedings of the first RILEM international symposium onself-compacting concrete, Stockholm; 1999. p. 523–35.

[3] Kurita M, Nomura T. Highly-flowable steel fiber-reinforced concretecontaining fly ash, vol. 178. ACI SP; 1998. p. 159–75.

[4] Kim JK, Han SH, Park YD, Noh JH, Park CL, Kwon YH, et al. Experimentalresearch on the material properties of super flowing concrete. In: Productionmethods and workability of concrete. E&FN Spon; 1996. p. 271–84.

[5] Miura N, Takeda N, Chikamatsu R, Sogo S. Application of super workableconcrete to reinforced concrete structures with difficult constructionconditions, vol. 140. ACI SP; 1993. p. 163–86.

[6] Khurana R, Saccone R. Fly ash in self-compacting concrete. Proceedings of fly,ash, silica fume slag and natural pozzolans in concrete, vol. 199. ACI SP; 2001.p. 259–74.

[7] Siddique R. Properties of self-compacting concrete containing class F fly ash.Mater Des 2011;32(3):1501–7.

[8] Bilodeau A, Malhotra VM. High-volume fly ash system: concrete solution forsustainable development. ACI Mater J 2000;97(1):41–8.

616 P. Dinakar et al. / Materials and Design 46 (2013) 609–616

[9] Bouzoubaa N, Lachemi M. Self compacting concrete incorporating highvolumes of class F fly ash, preliminary results. Cem Concr Res2001;31(3):413–20.

[10] Dinakar P, Babu KG, Santhanam M. Durability properties of high volume fly ashself compacting concretes. Cem Concr Compos 2008;30(10):880–6.

[11] Dinakar P, Babu KG, Santhanam M. Mechanical properties of high volume flyash self compacting concrete mixtures. Struct Concr J Fib 2008;9(2):109–16.

[12] Dinakar P. Design of self-compacting concrete with fly ash. Mag Concr Res2012;64(5):401–9.

[13] Siddique R, Aggarwal P, Aggarwal Y. Influence of water/powder ratio onstrength properties of self-compacting concrete containing coal fly ash andbottom ash. Constr Build Mater 2012;29(1):73–81.

[14] Dinakar P, Babu KG, Santhanam M. Corrosion resistance performance of highvolume fly ash self compacting concretes. Mag Concr Res 2009;61(2):77–85.

[15] Felekoglu B, Turkel S, Baradan B. Effect of water/cement ratio on the fresh andhardened properties of self-compacting concrete. Build Environ2007;42(4):1795–802.

[16] Sahmaran M, Yaman O. Hybrid fiber reinforced self-compacting concrete witha high volume coarse fly ash. Constr Build Mater 2007;21(1):150–6.

[17] Seleem HEH, Noval N. The effect of steel fibers on fresh and hardened self-compacting concrete properties. In: Proceedings of an internationalconference: future vision and challenges for urban development, Housingand Building Research Centre, Cairo; 2004. 13p.

[18] IS: 1489 (Part 1). Specification for Portland pozzolana cement (fly ash based).Bureau of Indian Standards, New Delhi; 1991.

[19] Okamura H, Ouchi M. Self compacting concrete. J Adv Concr Technol2003;1(1):5–15.

[20] DIN 1045. Beton und Stahlbeton. Koln: Beton Verlag GMBH; 1988.[21] Guru Jawahar J, Sashidhar C, Ramana Reddy IV, Annie Peter J. Effect of coarse

aggregate blending on short-term mechanical properties of self compactingconcrete. Mater Des 2013;43(1):185–94.

[22] Self compacting concrete European project group. The European guidelines forself-compacting concrete. BIBM, CEMBUREAU, EFCA, EFNARC and ERMCO.<http://www.efnarc.org.2005> [accessed 27.01.09].

[23] BS EN-12390-8. Depth of penetration of water under pressure. BritishStandards Institution; 2000.

[24] Liu M. Self-compacting concrete with different levels of pulverized fuel ash.Constr Build Mater 2010;24(7):1245–52.

[25] Nehdi N, Pardhan M, Koshowski S. Durability of self-consolidating concreteincorporating high-volume replacement composite cements. Cem Concr Res2004;34:2103–12.

[26] ACI Building Code 318-99. Building code requirements for structural concrete(ACI 318-99) and commentary (ACI 318R-99). Reported by ACI Committee318; 1999. 392p.

[27] CEB – FIB – 90. Model code for prediction of elastic modulus; 1990.[28] Persson B. Creep shrinkage and elastic modulus of self-compacting concrete.

In: First international RILEM symposium on self-compacting concrete. RilemPublications S.A.R.L.; 1999. p. 239–50.

[29] Persson B. A comparison between mechanical properties of self compactingconcrete and the corresponding properties of normal concrete. Cem Concr Res2001;31:193–8.

[30] Gram HE, Piiparinen P. Properties of SCC-especially early age and long termshrinkage and salt frost resistance. In: First international RILEM symposium onself-compacting concrete. Rilem Publications S.A.R.L.; 1999. p. 211–26.

[31] Dehn F, Holschemacher K, WeiXe D. Self-compacting concrete timedevelopment of the material properties and the bond behaviour. In: TheLeipzig annual civil engineering report, Germany LACER No. 5; 2000. p. 115–24[ISSN 1432-6590].

[32] Jacobs F, Hunkeler F. Design of self-compacting concrete for durable concretestructures. In: First international RILEM symposium on self compactingconcrete. Rilem Publications S.A.R.L.; 1999. p. 397–410.

[33] Sonebi M, Bartos PJM. Hardened SCC and its bond with reinforcement. In: Firstinternational RILEM symposium on self compacting concrete. RilemPublications S.A.R.L.; 1999. p. 275–90.

[34] CEB-FIP. Diagnosis and assessment of concrete structures-state of the artreport. CEB Bull 1989;192:83–5.

[35] Marsh B. High-volume fly ash concrete. Concrete (London) 2003;37(4):54–5.[36] Martys NS, Ferraris CF. Capillary transport in mortars and concrete. Cem Concr

Res 1997;27(5):747–60.[37] Ramezanianpour AA, Pilvar A, Mahdikhani M, Moodi F. Practical evaluation of

relationship between concrete resistivity, water penetration, rapid chloridepenetration and compressive strength. Constr Build Mater 2011;25(5):2472–9.

[38] Shi C. Effect of mixing proportions of concrete on its electrical conductivity andrapid chloride permeability test results. Cem Concr Res 2004;34(3):537–45.

[39] Kuroda M, Watanabe T, Terashi N. Increase of bond strength at interfacialtransition zone by the use of fly ash. Cem Concr Res 2000;30(2):253–8.

[40] Mehta PK, Monteiro PJM. Concrete-microstructure, properties, and materials.Indian ed. Chennai, India: Indian Concrete Institute; 1997.

[41] Shehata MH, Thomas MDA, Bleszynski RF. The effect of FA composition on thechemistry of pore solution. Cem Concr Res 1999;29(12):1915–20.