As worldwide electricity consumption has increased, so too has the waste of electricity. Palm oil fuel ashis a waste material generated in power plant due to burning of palm oil industry waste as a fuel togenerate electricity. Annual production of such a massive amount of waste requires a huge disposal fieldthat would be a threat to the environment. Therefore, due to the abundance and high pozzolaniccharacteristics, palm oil fuel ash has attracted many researchers to evaluate the potential of its use inconstructional materials. In this study, self-compacting concretes were produced by incorporation ofpalm oil fuel ash at 10, 15 and 20% by weight of Portland cement and their mechanical and durabilitypotential were evaluated under normal, acid and sulfate attack conditions. It was observed that incor-poration of palm oil fuel ash in self-compacting concrete enhanced the acid and sulfate resistance,reduced the dry shrinkage and surface water absorption of the self-compacting concrete without anadverse effect in final compressive strength of the products.
Self-compacting concrete (SCC) is highly flowable concrete thatspreads and flows under its own weight and completely fill form-works with congested reinforcement without the need of externalconsolidation (Khayat, 1999). Segregation resistance and the abilityof SCC to remain homogenous and stable is necessary (EFNARC,2002). SCC is mainly characterized by its remarkable workabilityin the fresh state (Okamura et al., 2000; Ozawa et al., 1990).Reduction in labor cost and construction time, quality improve-ment, and a quality finished surface make it superior to conven-tional concrete (Khayat et al., 1999). However, producing self-compacting concrete with high fluidity and desirable strength re-quires more cement content and inclusion of costly chemical ad-mixtures to reducewater to binder ratio leading to increase the costof SCC and higher carbon dioxide emissions compared to conven-tional concrete. Moreover, the higher consumption of Portlandcement in SCC mix design results in increasing hydration heat andhigh autogenous shrinkage (Sabet et al., 2013).
Incorporating pozzolanic materials such as fly ash, rice husk ash,silica fume, and palm oil fuel ash in SCC enhances energy andmaterial conservation, cost efficiency, durability performance,jobsite productivity, overall construction sustainability other thanreducing heat of hydration, autogenous shrinkage (Hossain andLachemi, 2009; Kanadasan and Abdul Razak, 2015; Wu et al.,2014). In addition, in terms of environmental considerations,incorporation of the cementitious supplementary material resultsin saving energy and resources by substantially reducing green-house gas emission which is due to obviation of limestone calci-nation, fuel combustion in the kiln, manufacturing andtransportation processes associated with production of Portlandcement (Cheerarot and Jaturapitakkul, 2004; Dinakar et al., 2008;Ranjbar et al., 2015; Tangchirapat et al., 2007).
Palm oil fuel ash (POFA) is produced by the palm oil industry as aresult of the burning of empty fruit bunch (EFB), fiber and oil palmshell (OPS) as fuel to generate electricity at temperatures of about800e1000 �C and the waste, collected as ash, becomes POFA(Nagaratnam et al., 2015). Malaysia produced about 3 million tonsof POFA in 2007 while 100,000 tons of POFA is being producedannually in Thailand, and this production rate is likely to increasedue to increased plantation of palm oil trees (Chindaprasirt et al.,2007; Johari et al., 2012a; Ranjbar et al., 2014b; Tangchirapatet al., 2007). The POFA produced in the palm oil mills is dumped
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into open fields without any profitable return resulting in massivesolid disposal which occupies vast fields and causes environmentalpollution (Chindaprasirt et al., 2007, 2008; Sata et al., 2004). In viewof environmental contamination, palm oil industry has started tolook for an effective solution so that this huge volume of waste canbe utilized. A successful approach to this problem can be linked toutilizing POFA as an alternative material in concrete and con-struction material.
Therefore, abundance of POFA concomitant with silica richcharacteristics paves the way for its usage as partial replacement ofPortland cement and the development of sustainable concrete.Moreover, several studies conducted to investigate theeffectof POFAon the durability performance of concrete reported that incorpora-tionof POFA improves thedurability characteristic of concretedue toenhancement of the production of CeSeHgel andhydrationprocessover time (Awal and Hussin, 1999; Chindaprasirt et al., 2007; Ismailet al., 2010; Tangchirapat et al., 2009). However, to the best of theauthors' knowledge, the utilization of POFA as a pozzolanicmaterialas partial replacement of Portland cement has not been investigatedextensively in self-consolidating concrete (Rahman et al., 2014).Considering the particle agglomeration and inherent high waterdemandproperties of POFA (Ranjbar et al., 2014a), it is expected thatits incorporation into Portland cement based self-consolidationconcrete will reduce slump and consequently will cause anadverse impacts on the freshproperties of thematrix. Therefore, thisstudy was conducted to explore the influence of the partialreplacement of POFA in a Portland cement based self-consolidationconcrete with 10, 15 and 20% binder weight in fresh and hardenedstate under an applied compression load. Moreover, the matriceswere exposed to acid and sulfate attack for a period of 75 and 180days, respectively, to investigate POFA incorporation effects ondurability of the Portland cement based self-consolidation concrete.
2. Materials characterization and analysis methods
2.1. Materials
2.1.1. Cement and POFAOrdinary Portland cement (OPC) type I used in this study was
received fromTasekCorporationBerhad (Malaysia). ThePOFAused inthis study was obtained from palm oil mill located in SelangorMalaysia. The as received POFA from the power plant contained largeparticles and impurities. Furthermore, since POFA was kept in anopen area after production with an unknown moisture condition,prior to mixing process POFA was dried at 105 �C for 24 h. Next, thedried POFAwas sieved through a 300 mm sieve to remove large par-ticlesand impurities. Finally, a LosAngelesmachinewasused togrindthe POFA to increase the fineness and consequent reactivity (Kumarand Kumar, 2011). The physical properties and chemical composi-tion of the materials are presented in Tables 1 and 2, respectively.
The morphology of the OPC and POFA is shown in Fig. 1. Asobserved, both of the materials have an agglomerated particleshape, while the POFA has amore porous structure compared to theOPC. As shown in Fig. 2, the particle size distribution of the mate-rials after processing of the POFA become smaller than that of OPC.
Table 1Physical properties of coarse and fine aggregate, OPC and POFA.
2.1.2. AggregateLocal mining sand with a fineness modulus of 2.88, specific
gravity of 2.56, and water absorption of 1.13% was used as a fineaggregate. Crushed limestone with a maximum size of 12.5 mm,specific gravity of 2.62, and water absorption of 0.43% was used ascoarse aggregate. The conducted test procedures and obtained datawere in accordance with ASTM C33 in order to comply withrequirements.
2.2. Mix proportions
Ground POFAwas used as partial replacement of Type I Portlandcement at proportions of 10%, 15%, and 20% of binder weight con-tent. The mix designs of the self-consolidating concretes included480 kg/m3 of binder and water to binder ratio of 0.35 for all spec-imens as shown in Table 3. Sika Viscocrete-1600 superplasticizer(Sika Kimia Sdn Bhd, Malaysia) was used in the self-compactingconcrete mixtures in order to obtain the fresh properties. SikaViscocrete-1600 is an extreme water reduction which meets therequirements for superplasticizers according to ASTM C494 Type G.To obtain similar workability for the specimens, higher super-plasticizer was used in mix design of higher POFA content matricesbecause of the agglomerated shape of POFA particles leading to thedemand for more energy to roll over one another.
2.3. Specimen preparation and testing methods
The coarse and fine aggregate were mixed first. Then, 10% waterwas added. Next, cement and POFA were added to the mixturefollowed by addition of 50% more water. The remaining waterproportion was added in to the mixture with superplasticizer sothat a homogenous mixes could be obtained. Generally self-compacting concrete mixing process requires more time thanconventional concrete mixes. It should be noted that POFA inclu-sion leads to further level of difficulty in fulfilling the requirementsof tests for SCC, therefore, maximum POFA content chosen in thisstudy was limited to 20% because of the higher water demand ofthe ash (Ranjbar et al., 2014b). Fresh properties of the SCC weretested in accordance to the specifications of EFNARC (2002) forfilling, passing abilities, and segregation resistance after mixing.Initially, the mixes were subjected to slump flow and T50 tests(EFNARC, 2002). If both tests meet the standard requirements, then
Fine aggregates OPC POFA
4.761.132.88
91 9614.6 10
2.56 3.15 1.81
Fig. 1. FESEM images of a) Portland cement and b) POFA particles.
Fig. 2. Particle size distribution of ground POFA and Portland cement.
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mixes would be subjected to V-funnel, L-box, J-ring and segrega-tion test. The schematic images of the experimental setups areshown in Fig. 3.
Fresh properties of the SCCs were determined immediately aftermixing. Then the concrete mixes were poured into 100 mm cubesand 100*100*500 mm prisms in two layers of about 5 cm height.Thematerial was spread in themolds and filled all the corners by itsself-weight. Next, the top surface of the specimens were smoothedand leveledmanually. After casting, all the specimens were coveredfor 24 h in an ambient condition. Afterward, the samples weredemolded and cured in water at 25 �C ± 3 until the day of testing.
Drying shrinkage strain of concrete was measured on100 � 100 � 500 mm prisms by using Mitutoyo Absolute Digimatic(Mitutoyo Corp, Tokyo, Japan). The ASTM C-157 was followed fordrying shrinkage test. The shrinkage specimens were then removedfrom the molds 24 h after casting and cured in tap water for 7 days.After 7 days, the specimens were removed from the water, wipedand fitted with demec points at the sides. The concrete specimenswere then placed in a room with a temperature of 28 ± 3 �C and arelative humidity of 78 ± 2%. The variation of length for all speci-mens was recorded by Mitutoyo Absolute Digimatic starting at 28days and running until day 365.
The initial surface absorption test (ISAT) of the harden speci-mens was determined on 100 mm cubes pre-cured in water for the
Table 3Mix design of samples.
Mixes Water/cement Cement (kg/m3) POFA (kg/m3) Fine aggregate (kg/m
28 and 56 days in accordancewith BS 1881-208. The bulk density ofthe final green bodies wasmeasured using the Archimedesmethod.The X-Ray Diffraction (XRD) patterns were measured on anEmpyrean PANALYTICAL diffractometer before and after exposureto acid and sulfate attack to investigate the effect of POFA contenton self-compacting concrete durability withmonochromated Cu Karadiation (l ¼ 1.54056 Å), operated at 45 kV and 40 mAwith a stepsize of 0.026 deg and a scanning rate of 0.1 deg s�1 in the 2q range of20e40 deg. Field Emission Scan Electron Microscopy (FESEM CARLZEISS- AURIGA 60) images were obtained to observe the influenceof the POFA content on the microstructures of the self-compactingconcrete. The compressive strengths of the specimens were ob-tained from 100mm cubes at 3, 7, 28, 56, 90 and 180 days; however,100 � 100 � 500 mm prisms were prepared for four point bendingto obtain flexural strength of the specimens with effective span of400 mm. Mechanical test were performed with ELE AutoCompressive Testing Machine with capacity of 3000 kN as per BSEN 12390-3:2002.
The chemical resistance of the concrete specimens was inves-tigated through chemical attack by immersing 100 mm cubes inHCl acid solution, prepared over a period of 1800 h (75 days). After7 days water curing, the specimens were immersed in 3% HCl so-lutionwith a pH of about 2. This solutionwas substituted at regularintervals of 2 weeks to keep a constant concentration during thetest period. The reduction in compressive strength and the loss ofmass of the concrete specimens were measured after 1800 h.
Moreover, to investigate sulfate attack of concrete, 100 mmcubes were immersed in 5% MgSO4 (by mass) solution after 7 dayscuring inwater and the compressive strength was determined after12 months.
3. Results and discussion
3.1. Fresh properties
The test results for fresh properties of SCC were determined byconducting the filling ability tests (slump flow, T50cm spread time,and V-funnel flow time), passing ability tests (J-ring flow and L-box), and segregation resistance test (segregation index) ofdifferent SCC mixtures. The fresh properties test results were givenin Table 4. For filling ability requirements, all the concrete mixeswere designed to have a slump flow of average diameter of
3) Coarse aggregate (kg/m3) Water (kg/m3) Superplasticizer (% of binder)
758 168 1.3758 168 1.4758 168 1.5758 168 1.8
Fig. 3. Scheme of a) slump flow and T50 tests, b) V-funnel, c) L-box and d) J-ring (EFNARC, 2002).
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680 ± 20 mm which was achieved by using varying amounts ofViscorete superplasticizer. The increase in POFA content of mix-tures resulted in the reduction of workability due to higher specificsurface area of the POFA particles which led to more water demandto ease the movement and rolling of particles over each other. Asstated earlier, POFA particles were ground to become more favor-able material. However, there are still either some unground or lessground particles remaining in the POFA. This can be found in Fig. 1from which it can be inferred that uncrushed and crashed (un-ground and ground) POFA particles are remarkably porous andagglomerated, whereas the Portland cement particles were densereven with crushed shape. As water content increased the porositywas increased which could result in adverse effects on the freshmaterial properties. Therefore, replacement of considerableamount of water with small amount of superplasticizer was abeneficial method tominimize the risk of deterioration in hardenedconcrete due to high water/binder ratio. The results of V-funnel andT50s flow times for POFAmixtures were close to the control mixtureand ranged between 5.6e8.75 s and 3e4.57 s, respectively, asshown in Table 4. Moreover, the obtained data showed all mixturesfulfill the requirements of passing ability and segregation resistanceas per EFNARC (2002). The higher content of POFA showed increasein the viscosity of concrete which led to lower slump flow, J-ring,and L-box, whereas it increased T50 and v-funnel flow time and
Table 4Fresh properties of SCC.
Mix no. Filling ability
Slump flow (mm) T50cm spread time (s) V-funnel flow
segregation index. To sum up, it can be inferred that up to 20% ofcement could be replaced by ground palm oil fuel ash withoutadverse effect on fresh properties of SCC. However, the results offresh properties are in good agreement with previous studies re-ported by Sata et al. (2007).
3.2. Mechanical properties
The bulk density of the specimens was reduced by incorporatingand increasing the percentages of POFA content in the SCC aspresented in Fig. 4. The highest reduction in bulk density was 5.75%due to inclusion of 20% POFA in SCC. The bulk density for SCC10 andSCC15 were reduced by 3.68% and 4.96%, respectively, in compar-ison with the specimens without POFA. The reduction of bulkdensity could be explained in several ways. The key reason could bethat POFA has a lesser specific gravity than does cement (Ranjbaret al., 2014b). Moreover, it is expected that crushed shape of thePOFA particles has potential to trap air bubbles which manifestedthemselves in the form of porosity in the final product (Ranjbaret al., 2014a). The FESEM images in Fig. 5 illustrate self-compacting concrete without POFA content and with 20% POFAreplacement. From Fig. 5 it can be inferred that the specimenwithout POFA content was denser compared to the specimens with20% POFA content. This can be attributed to the micro-pores which
Passing ability Segregation resistanceSegregation index (%)
time (s) J-ring flow (mm) L-box
690 97 6.67670 93 8.7650 89 10.8630 84 13.9
Fig. 4. Bulk density of POFA based self-compacting concrete.
Fig. 6. Drying shrinkage and reduction rate of drying shrinkage (RRDS) of self-compacting concretes.
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were filled by very fine crystalline structure over time which ishighlighted in Fig. 5.
Fig. 7. Compressive and flexural strength development of POFA based self-compactingconcrete.
3.3. Drying shrinkage strain
Drying shrinkage and reduction rate of drying shrinkage (RRDS)of self-compacting concretes were presented in Fig. 6. Dryingshrinkage takes place when concrete is hardened and dried out atthe early age resulting in the formation of microcracks in matrix.These cracks provide easy access to harmful agents leading toadverse effect on durability of the final product. The dryingshrinkage of all self-compacting concrete specimens was increasedduring the first 90 days. Fig. 6 showed that the incorporation ofpalm oil fuel ash reduced the drying shrinkage strain at any per-centage of replacement (up to 20%). After 360 days of drying, thedrying shrinkage strain of control sample was 395 microstrainwhile those of concrete with 10%, and 20% POFA were 291 and 328microstrain, respectively. RRDS for self-compacting concrete spec-imens with POFA was also presented in Fig. 6. Two clear trendswere observable: first the highest reduction in drying shrinkageoccurred with incorporation of 10% POFA, whereas the lowest ratebelonged to the specimenwith 20% POFA.While there was a similartrend of RRDS for all samples, the highest effect of POFA inclusion indrying shrinkage reduction occurred within the first 28 days. Thelowest impact on drying shrinkage reduction due to inclusion ofPOFA was in 56 days, thereafter with a slight increase in RRDS, aconstant trend was registered. It is noteworthy that althoughincorporating POFA into self-compacting concrete resulted inhigher volume of pores, POFA exhibited a proper pozzolanic reac-tion suggesting a high pack effect. High packing effect was a properarrangement of small particles which fill the voids and contributeto the increment of compressive strength (Goldman and Bentur,1993; Johari et al., 2012b). It should be noted that although the
Fig. 5. FESEM images of a) self-compacting concrete w
number of pores were increased due to addition of POFA content,pozzolanic reaction of POFA caused the transformation of largepores into fine pores. Refining pore size in POFA self-compactingconcrete reduced the loss of water and therefore diminishedshrinkage strain (Tangchirapat and Jaturapitakkul, 2010; Zhang andLi, 2011).
3.4. Compressive and flexural strength
The compressive and flexural strength development of SCCconcretes containing ground POFA over 180 and 28 days wereshown in Fig. 7, respectively. The specimens containing high vol-ume of POFA, 15 and 20% gained lower compressive strength in theearly days of curing in comparison with the conventional SCCwithout POFA content. The reduction in the early age of compres-sive strength might be attributed to the dilution effect as part of the
ithout POFA content, b) with 20% POFA content.
Fig. 8. Initial surface water absorption of POFA containing self-compacting concrete a)after 28 days, b) after 56 days.
Fig. 9. Reduction in compressive strength of POFA contained self-compacting concretedue to sulfate attack.
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cement was replaced by the POFA. Generally, the reaction processof POFA/Cement concrete can be divided into two major stages.First stage is mostly attributed to the reaction of cement and water;second stage is attributed to pozzolanic activity of ground POFAwith liberated portlandite from cement hydration. Reaction of alite(tricalcium silicate) andwater results in CeSeH gel and portlandite.Since hardening of CeSeH gel is the main strength gain factor ofconcrete, decreasing of the Portland cement content resulted inreduction in strength in concrete at early ages. Silica content inPOFA, meanwhile, is capable of reacting with portlandite andgenerates secondary CeSeH gel. The extra CeSeH gel was pro-duced as a pozzolanic reaction of POFA depending on the genera-tion of portlandite in reaction of alite and water. Therefore, thestrength gain of this stage will be delayed. On the other hand, thepozzolanic reaction mainly contributes to increasing thecompressive strength of concrete at later ages by improving theinterfacial bond between paste and aggregate. Also, the fineness ofground POFA improves the strength of concrete by filling the gapsbetween cement particles (Ismail et al., 2010; Tay and Show, 1995).From Fig. 7 it is learned that the influence of ground POFA oncompressive strength of specimens older than 28 days was com-parable or higher than the corresponding plain concrete dependingon the replacement percentages. The flexural strength of self-compacting specimens was also shown in Fig. 7 at 7 and 28 daysof age. The 7 day flexural strengths ranged from 5.12 to 6.19 MPa,whereas the 28 day flexural strengths ranged from 5.46 to6.90 MPa. The ratio of the flexural strength to the correspondingcompressive strength at 28 days was ~9.2% and was comparable tothe conventional concrete. Nevertheless, incorporation of POFA inany volume lowered flexural strength compared to the concretespecimens without POFA. This might be correlated to the porousstructure of self-compacting concretewith POFAwhich led to stressconcentration and weakening of the bond between aggregate andpaste.
3.5. Initial surface water absorption test
The initial surface absorption test was conducted to obtain theflow within the concrete surface at intervals of 10, 30 and 60 minfor specimens at 28 and 56 days of age. Test results presented inFig. 8a and b showed that by incorporating POFA in SCC the ISATvalues were decreased. The lowest flow rate was at 20% cementreplacement level at all ages. The initial surface absorption of SCC10and SCC20 for 10 min interval was 16% and 32%, respectively, whichwere lower than control mix (SCC0) at 28 days. Although SCC20 hadslightly lower compressive strength than that of SCC0 and SCC10mixes, SCC20 had lower concrete surface absorption. The observedreduction in initial surface absorption could be attributed to fineclose porosity of POFA contained matrix which resulted in omittingpore networks in concrete matrix. Moreover, the POFAwith smallerparticle size were placed between cement particles enhancing themicrostructure of the matrix and filling the pores in POFA basedself-compacting concrete.
3.6. Sulfate attack
The reduction in compressive strength for concrete immersed in5% magnesium sulfate (5% MgSO4 by the weight of water) for 12months was shown in Fig. 9. The compressive strength losses ofSCC0, SCC10, SCC15, and SCC20 immersed in 5% MgSO4 solutionwere approximately 9.6% and 8.3%, 7.8%, and 7.2%, respectively,compared to the samemixtures cured inwater for the same period.
It can be seen that the highest reduction in compressivestrength was in the plain concrete SCC0, while the lowest loss incompressive strength was observed in 20% cement replacement.
The higher resistance to sulfate attack for concrete including POFAwas attributed to the pozzolanic reaction of POFA. The pozzolanicreaction reduced the amount of free calcium Ca(OH)2 producedfrom the cement hydration through forming secondary CeSeHwhich resulted in pore refinement and denser concrete. In addition,the high fineness of POFA reduced the permeability of concreteresulting in sulfate attack resistance improvement. The results werein line with previous studies conducted on normally vibrated andhigh strength concrete. Previous literature (Tangchirapat et al.,2009, 2012) reported that the use of POFA in concrete increasedthe resistance to sulfate attack and the recommended percentagewas also up to 20% replacement.
Fig. 11. Reduction in compressive strength of POFA containing self-compacting con-crete due to HCL attack.
N. Ranjbar et al. / Journal of Cleaner Production 112 (2016) 723e730 729
3.7. Acid attack
The resistance against acid attack of concrete cube specimenswas evaluated by measuring the reduction in compressive strengthand mass loss of the specimens immersed in a 3% hydrochloric acidsolution (HCl) for 1800 h. The mass loss of the specimens is shownin Fig. 10. The higher mass loss of the control specimens was mainlydue to the higher deterioration at the corners and edges. Theimprovement in acid deterioration resistance in higher POFA con-tent is attributed to the pozzolanic reaction of the POFA conversionof calcium hydroxide (Ca(OH)2) to the additional CeSeH gel.Therefore, the Ca(OH)2, which reflects the weakest product fromcement hydration was reduced proportionally as POFA content wasincreased.
The relationship between the POFA content and the reduction incompressive strength of concretes was shown in Fig. 11. The testresults showed that SCC concretes with POFA showed betterresistance against the acid after 1800 h of immersion. By inclusionof POFA in the SCC mixture the mass loss of concrete significantlyreduced. The better resistance of the self-compacting concretecontaining POFA against acid attack was attributed to the pozzo-lanic reaction of POFA conversion of calcium hydroxide Ca(OH)2 tothe secondary CeSeH gel leading to denser concrete. Therefore, theCa(OH)2, considered the weakest product from cement hydrationand highly susceptible to chemical attacks, was reduced. In addi-tion, the better finishing surface and the minimum empty voids onthe concrete surface of the specimens containing POFA led to alower penetration of acid solution into the interior of concrete, andimproved its resistance against acid attack (Budiea et al., 2010).
3.8. XRD analysis
XRD spectra of the SCC with and without 20% of POFA undernormal condition, sulfate and acid attack were presented in Fig. 12.The main crystalline phases which were identified for the SCCconcretewith andwithout POFA content are quartz, calcium silicatehydroxide and portlandite. The detected pure quartz did notrepresent one of the hydration products which might be due to thepresence of high SiO2 content in the sand particles. XRD patterns ofPOFA content specimens showed small trace of portlandite sincethe pozzolanic reaction used the portlandite to produce CeSeH gel.When SCC was exposed to sulfate attack, sulfate ions and calciumhydroxide Ca(OH)2 produced from cement hydration reacted andyielded gypsum. The formation of gypsum caused softening and
Fig. 10. Mass loss of POFA incorporated self-compacting concrete because of acidattack.
loss of concrete strength (ACI Committee, 1990). However, thespecimens subjected to acid attack showed the patterns of calciumchlorate and calcium chlorite. Since incorporation of the POFA ledto reduction in the long term portlandite of the system, POFAcontaining SCC showed higher stability against sulfate and acidattack. Moreover, the expected close porosity and low surfacewaterabsorption blocked the acid and sulfate penetration; thereforesmaller volume of the specimens were exposed to chemical attackwhich led to increase in overall durability of the products.
Fig. 12. XRD patterns of SCC0 and SCC20 under normal condition, sulfate and HCLattack.
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4. Conclusions
In this investigation, the effect of POFA incorporation in self-compacting concrete under sulfate and chloride attack from theaspects of mechanical and microstructures were studied. Based onthe tests conducted, the following conclusions were drawn:
� Generally, POFA as awastematerial showed great potential to beused as a replacement of Portland cement in self-compactingconcrete preserving fresh, mechanical and durability proper-ties in an acceptable range.
� Incorporation of POFA led to reduction inworkability of the SCC;however, by additional superplasticizer the fresh properties ofthe SCCs POFA were kept almost the same.
� Increasing the POFA content resulted in reduction in early me-chanical properties while the final strength of the POFA con-taining SCC was comparable to the normal specimens. This wasattributed to the pozzolanic mechanism of POFA.
� The specimens which contained higher amount of POFA showedless surface water absorption and higher durability under acidand sulfate attack in comparison to the normal SCC excludingPOFA. Incorporation of POFA reduced the amount of portlanditein the system to produce CeSeH gel leading to densification ofthe matrix and blocking of open porosity networks.
Acknowledgment
This research work was funded by the University of Malayaunder High Impact Research Grant (HIRG) No. UM.C/HIR/MOHE/ENG/36/D0000036-16001 (Strengthening structural elements forload and fatigue).Wewould also like to acknowledge the assistanceof Mr. Sreedharan from the concrete laboratory of Department ofCivil Engineering of University of Malaya.
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