Critical review on Mix Proportioning stipulations for High Volume Fly ash concrete (HVFAC)

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056

Volume: 09 Issue: 08 | Aug 2022 www.irjet.net p-ISSN: 2395-0072

Critical review on Mix Proportioning stipulations for High Volume Fly ash concrete (HVFAC)

1 M.Tech Research Scholar, Department of Civil Engineering, Techno India University, Salt lake, Kolkata (West Bengal)

2Ph.D. Research Scholar, Department of Civil Engineering, Techno India University, Salt Lake, Kolkata (West Bengal)

3Professor, Department of Civil Engineering, Techno India University, Salt Lake, Kolkata (West Bengal) ***

Abstract - Today’s situation demands that concrete construction has to be eco-friendly as well as safe apart from being cost efficient so that society at large could be benefitted which makes large investments in the infrastructure projects. So, HVAFAC is widely used now a days as a replacement product to Portland cement which complies with the above statement. In this paper mix proportioning of high volume of fly ash concrete (HVFAC) is thoroughly studied from different research papers. Less water to binder ratio (w/b) plays an important role in mix proportioning. Fineness of fly ash is also an important aspect in this regard. The age factor also has a significant effect on high volume fly ash concrete, i.e. with the increase in number of days high volume fly ash concrete grabs more compressive strength.

Key Words: eco-friendly, cost efficient, Portland Cement, HVFAC, mix proportioning, age factor, w/b (water to binder ratio), fineness, compressive strength.

1. INTRODUCTION

General

Inrecentscenarioenvironmentalfriendlyproductsareused. Itisbeingtriedbytheresearcherstomaketheconcreteas environmental friendly as possible. So in this case HVFA (highvolumeflyash)isusedasanalternativeto Portland Cementinhighperformanceconcretemixtures.Theuseof ordinaryportlandcementishighlyminimizedwiththeuse ofhighvolumeflyashinconcretemixtures.Theselectionof mineral and chemical admixture should be done very judiciouslytoproducehighperformanceconcrete.

1.2 Mix proportioning

The process through which the correct combination of its ingredientsisdeterminedthatistheresultingmixgivesthe desired characteristics with minimum cost is called mix proportioning. The process of proportioning of the constituents of concrete like cement, water, FA, CA, other SCMsandchemicaladmixturesisdefinedasmix-design.The qualityoftheseconstituentmaterials,water/cementratio and the mixing procedure plays a very important role in

achieving the targeted strength and durability of the concretemix,whichfinallycontrolsthecostoftheproject. A To find the desired characteristics of concrete the mix proportionsofconcretehastobemoreorlessmodifiedto establishthecorrectmixdesign TheproportioningofHPC involvesproperprocedureassummarizedinthefollowing steps:

1. Selection of materials: This involves selecting good quality,locallyavailableconstituentmaterials.

2. Mix-proportioning: This involves decision for mixproportioning of selected materials from the available literatureorguidelines.

3.Optimizingthematerials:Thisinvolvesoptimizingthe proportioningbyusingempiricalortheoreticalconcepts.

4.Testingofsample:Thisinvolvesfinallyevaluatingthe rheologicalpropertiesandthemechanicalpropertiesofthe optimizedmix.

Inmakinghighperformanceorhighstrengthconcretethe constituentsofhighqualityareused.Theseareveryuseful inobtainingthehighstrengthofconcrete.Theconstituents may comprises of a mixture of strong aggregate, a higher Portland cement content, low water/binder ratio, and selectedadmixture.Flyashisamineraladmixturewhichis usedinconcrete,aby-productofcoal-firedpowerstations. Flyashasareplacementofcementhasprovenitsacceptance andhasgivenmanyadvantagesintheearlyandlaterstages ofconcreteaftermixing.Oneoftheseadvantagesisthatitis moredurablethannormalconcrete Inthe1980stheterm highvolumeflyashwasfirstused byMalhotraatCANMET, thatisthemaximumpercentagesofcementwasreplacedby fly ash which is above 50% came into the dictionary of concrete.Thoughhighpercentagesofcementinhighvolume fly ash concrete is replaced by fly ash, it still gives high performance concrete The particle size of fly ash is very influential in fly ash reactivity. One of the factors giving great influence in fly ash reactivity is the particle size Generallyflyashparticlesrangingfrom10μmto50μmact asvoidfillersinconcrete,whereassmallerparticleswhich aresmallerthan10micronsarepozzolanicreactive.

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2. MATERIALS

2.1 Fly ash

Flyashisanenvironmentalfriendlyproductwhichisvery usefulinconcrete.Sinceresearchersareingreatsearchto replacecementwithanenvironmentalfriendlyproduct,so flyashisverymuchacceptableinthiscase.Flyashalmost hasmanysimilaritieswiththatofcement.Thesizeofflyash alsohasagreatimpactinreplacingcement.Thesizesflyash variesfrom1µmto150µmconsistingofglassyspheres.The typicalsizeofflyashinparticlesizedistributionisunder20 µm.Thesizeofflyashmainlydependsonthesourcefrom whereitisextractedandtheequipmentwithwhichdustis collected.Theuseofagoodflyashaffectstheworkability, durability,dryingshrinkage,etc.,thatis,itgreatlyimproves thesementionedconditions.Theflyashalsohelpsincostcutting. The use of fly ash reduces the use of cement in concrete and hence reducing the cost. The thermal power stationsalsofindsitdifficulttodisposethewastematerial, so,utilisingitcontributestotheadvantagesofusingflyash.

2.2 Portland cement

Portlandcementisthecementthatisregularlyusedinour daytodayconstruction.Itisthemostimportantconstituent amongalltheconstituentsinmixproportioningofconcrete. Itisthebindingmaterialoftheconcretemixture.Ithelpsto gain compressive strength of concrete. But production of cement emits carbon dioxide which is the main environmental cause to replace the cement with other environmentalfriendlyproduct.Butresearchersarefinding ithardtoreplaceitwithothersupplementarycementitious materials. So, now it is being tried to replace the cement partiallynotfully,butinhugeamountssothatotherwaste materials, recycled products or environmental friendly productscanbeaddedtothemixproportioningofconcrete

2.3 Fine aggregate and Coarse aggregate

The particle shape and grading of fine aggregates are the important factors for the production of high performance concrete (HPC). Fine aggregates with rounded particle shape and smooth texture requires less water demand. Volume of fine aggregates should be kept minimum to increaseworkabilityandcompaction.Thefinenessmodulus offineaggregateslessthan2.5shouldnotbeused,asitis difficulttocompact.

In HPC, course aggregate may alsoaffect the concrete strength. Smaller size of aggregates known to produce higher strength of concrete. However for optimizing modulusofelasticity,creepanddryingshrinkage,highersize of aggregates are preferred. Usually the maximum size of coarseaggregatesmaybekeptataminimumsizeof10mm or12mm.

2.4 Silica fume

Silicafumeistheby-productofindustryproducingsilicon andferrosiliconalloy.Silicafumehasveryhighsurfacearea of the order of 15,000 m2/kg to 30,000 m2/kg which is measured by the method of nitrogen adsorption method. Thesizeofsilicafumeisverylesscomparedtothesizeof cementparticles.Thesizeisalmost100timeslessthanthat ofcementparticle.Thepercentagecontentofsilicainsilica fumeisalsoveryhighcomparedtothatpresentinPortland cement.Itisabout85-97%insilicafumecomparedto21.9% in the Portland cement Due to the presence of high percentagesofsilicainsilicafumeandextremesurfacearea it is said to be very effective pozzolanic material as comparedtoanyotherSCM.Theuseofsilicafumeenables theproductionofveryhighstrengthconcreteanditisvery usefulinattaininghighearlyageconcretestrength.So,while producing high performance concrete silica fume must be added.

2.5 Superplasticizer

Superplasticizers are very useful in concrete to gain high strength and better durability properties. It allows the production of concrete with low water-cement ratio. It allowsthereductionofwatercontentmorethan30%.Ithas many advantages like it increases workability as well as durability. It also increases slump which allows easy placementofconcrete.Ithasalsolittlebitdisadvantageslike itleadstotheadditionofcost,increasestheairentrainment in concrete, etc. There are different types of superplasticizers. SomeoftheseareSulphonatedMelamine –Formaldehyde Condensates (SME), Sulphonated Naphthalene Formaldehyde Condensates (SNF), Modified Lingosulphates (MLS), Polycarboxylate superplasticizerCarboxylatedAcrylic-EsterCo-polymers(CAEC),etc.

3. LITERATURE REVIEW

S. S.Awanti et al [1] ,Inthispaper differentconcrete mixtureswerepreparedwithHighVolumeFlyAshConcrete withreplacementofcementvaryingfrom50%to65%.The water/binder ratios taken were 0.30 and 0.35. Then compressivestrengthvalueswereobtainedatdifferentages. Inthiscasenearabout180concretecubesweremadefor determiningthecompressivestrengthproperty.Thewater tobinderratioisobtainedtobeveryeffective.Morethew/b ratio,lesserwillbethestrength.Identicaltrendisobserved with the case of Fly ash to binder ratio i.e with higher contentofflyash/binder(FA/borFA/cm)ratio,lowerwill bethecompressivestrengthofconcretespecimens.Butwith the increase in time it was observed that compressive strengthgraduallyincreases.

MochamadSolikinet.al.[2] ,Inthispaperthreedifferent factors were analyzed by preparing the different mixes to produce high strength concrete. Analyzation of different factors were the type of effective fly ash, kind of mixing

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waterandwhetherbasaltfibreshouldbeusedornot,etc. Thereweretwotypesofflyashusedinthisresearchsuchas rawflyashandultrafineflyash.Thekindofwaterthatwere usedinthemixarealsotwotypes,these werelime water and tap water. The utilization of basalt fibre was also studied.Sometimesitwasaddedtothemixturesometimes not. The different mixes prepared were ultra fine fly ash withoutthebasaltfibrebutwithtapwater,ultrafineflyash withbasaltfibreandlimewater,rawflyashwithbasaltfibre andtapwater,rawflyashwithoutbasaltfibrebutwithlime water. Then the compressive strength of these mixes in concrete was tested in concrete cylinder with 100 mm diameterandheight200mmconsideringthecuringagesat 28 days and 56 days. After it was found that the mix proportionwiththecombinationofhighvolumeultrafinefly ashandtheuseoflimewaterwithouttheuseofbasaltfibre has highest compressive strength than the other combinationsthatweretaken. Alsoitwasobservedthatthe optimum mix proportion almost gains the compressive strengthofnormalcementconcretein28days.

A.A. Momin et al [3] , In this paper locally available fine aggregates and coarse aggregates with ordinary portland cementandsuperplasticizer wereusedtoproduceconcrete ofstrengths60MPa,80MPaand100MPa.Toproducehigh strengthorhighperformanceconcretechemicaladmixtures mustbeaddedtothemixture.Silicafumemustalsobeadded to the mixture so as to gain strength similar to that of 70 MPa.Silicafumeabove20%isavoided,so,Alccofine1203 withsilicafumewasaddedtothemixsoastogainstrength equals to 100 MPa. Due to lower water to binder ratio a special method of mix design was used to produce high performanceconcrete.

Experimental investigation conducted by P. Saravanakumar et. al. [4] studied the use of natural aggregatesatdifferentpercentages. Flyashwasalsousedin place of cement at different percentages. Fly ash was replacedinthepercentagessuchas40%,50%,60%whereas recycledaggregateswerereplacedinthepercentagessuch as25%,50%and100% Duetothereplacementofnatural aggregates with coarse aggregates the compressive strengths at first got reduced but with the increase in number of days it showed less reduction in strengths. Similarlywiththeuseofflyashinplaceofcementstrengths atfirstgotreducedbutaftersometimesthestrengthswas almostsameasthatofnaturalconcrete.Duetotheuseofall these waste product huge money can be saved that is the costcanbesavedupto40%.Heredifferentcombinationscan beadoptedfordifferentconcreteconstructionwork.Thatis forpavementworkalargerecycledaggregatescanbeused.

According to the article by Saraswati et. al. [5] the query regarding suitability of the existing IS codes on fly ash concrete was assessed. Above 35% of fly ash is not consideredintheIScodesbutthequantityofflyashisnot limited according to IS codes in concrete. Moreover

regardingthemixingmethodofhighvolumeflyashconcrete IS codes does not give any guideline. However mixing method has influence on the performance of HVFAC and other types of concrete mixes. From the point of view of economy, HVFAC should be characterized for 56-day strength. But, the mix should have required strength for constructionpurposeaftertheminimumperiodrequiredfor curing,thatis,14days.HVFACshouldbecuredintwostages. Initial curing is dry curing for which no specification is availableinanyIScode.However,specificationofIS456on wetcuringisadequate.

4. RESULTS AND DISCUSSION OF PREVIOUS WORK

Underthistopicsometablesandgraphswillbe discussed whichwillgivesomeidearegardingpreviousresearchesof mixproportioningofhighvolumeflyashconcrete(HVFAC). Particularlywewilldiscussthepaper“MixDesignCurvesfor High Volume Fly Ash Concrete” by S.S. Awanti and AravindakumarB.Harwalkar.

Table -1: Mixproportionsofconcretemixeswithw/cm= 0.35

Mix designation/Ingredie nts

P.35 50F.3 5 55F.3 5 60F.3 5 65F.3 5

Waterinkg/m3 154 154 154 154 154 Cementinkg/m3 440 220 198 176 155

Flyashinkg/m3 0 220 242 264 285 Fineaggregatein kg/m3 871 807 800 794 787

Coarseaggregatein kg/m3 105 9 1059 1059 1059 1059

Superplasticizerin liter/m3 9.9 1.76 1.76 1.76 1.76

Table -2: Mixproportionsofconcretemixeswithw/cm= 0.30

Mix designation/Ingredie nts

P.30 50F.3 0 55F.3 0 60F.3 0 65F.3 0

Waterinkg/m3 132 132 132 132 132 Cementinkg/m3 440 220 198 176 155 Flyashinkg/m3 0 220 242 264 285 Fineaggregatein kg/m3 937. 6 871.0 864.8 0 858.2 851.8

Coarseaggregatein kg/m3 105 9 1059 1059 1059 1059

Superplasticizerin liter/m3 15.4 3.52 3.52 3.52 3.52

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InTable-1and Table-2twomixproportions ofconcrete mixesaretakenwithw/cmratio0.30and0.35respectively withreplacementofcementfrom30%to65%.

Table -3: Compressivestrengthsofdifferentconcrete mixes:

Mix designatio n

Cubecompressive strengthofconcrete inMPaattheageof

7 days 28 days 90 days

Ratioof7 day compressiv estrength to28day strength

Agefactor (Ratioof90 day compressiv estrength to28day compressiv estrength)

P.35 42.4 4 56.1 60.3 9 0.76 1.08

50F.35 27.2 5 42.4 4 51.8 1 0.64 1.22 55F.35 25.6 5 40.6 2 48.0 3 0.63 1.18

60F.35 21.6 5 35.1 7 42.3 6 0.62 1.20 65F.35 15.1 1 24.4 2 28.5 6 0.62 1.17

P.30 47.3 1 62.2 8 66.2 0 0.76 1.06

50F.30 30.5 9 52.1 62.9 3 0.59 1.21 55F.30 29.0 7 47.3 1 56.0 3 0.61 1.18 60F.30 25.0 7 40.8 4 46.4 3 0.61 1.14

65F.30 19.7 7 27.6 9 32.3 4 0.71 1.17

In this table the results of mix proportions that are taken from Table -1 and Table -2 can be observed clearly. From this table it can be said that with the increase in time the compressive strength gradually increases but with the increase in fly ash to binder ratio (fly ash/ cement) the compressive strength gradually decreases. The water to binder ratio also plays an important role in compressive strength.Fromthistabletheresultsarethatwithwaterto binderratio0.30thecompressivestrengthsarehigherthan withwatertobinderratio0.35.

5. CONCLUSIONS

[1] Aconcretemixthatispreparedwithlowerwaterto binderratiohashighercontributionofflyashthan the mixes that are prepared with higher water to binderratio.Thewatertobinderratioshouldnotbe morethan0.4incaseofHVFAC.

[2] While producing HVFAC in plants mechanised mixersshouldbepreferredhavingweightbatcher insteadofhandmixing.

[3] IncaseofHVFACmixwithloww/bratiothereisa potentialriskofplasticshrinkagecracksifnotcured early.So,afterplacingofconcretecuringshouldbe processedasearlyaspossible.

[4] Fly ash content and water to binder ratio greatly affectstheflyashreaction thatisthepastewhich hashighvolumeflyash,theflyashreactionislower whereastheconcretemixwhichhaslowvolumefly ash, the reaction will be higher. High Volume Fly Ash Concrete has lower early strength and the strengthgraduallyincreaseswithtime.

ACKNOWLEDGEMENT

IwouldliketoacknowledgemygratitudetowardsDr. Anup Kumar Mondal, Professor, Department of Civil Engineering,TechnoIndiaUniversity(WB)andProf.Saurav Kar, Assistant Professor, Department of Civil Engineering, HeritageInstituteofTechnology(WB)fortheirvaluableand resourceful guidance. Their supervision helped me to complete the review paper. It is due to their regular encouragements and valuable discussions for which this Reviewpapercouldbebroughttothecurrentshape.

REFERENCES

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[2] M. A. Caldarone, High strength concrete: A practical guide.NewYork,USA:Taylor&Francis,2009.

[3] CementandConcreteBasics.(2008,08October2008). High-strengthConcrete

[4] M. Taylor, et al., "Toughness measurements on steel fibre-reinforced high strength concrete," Cement and ConcreteComposites,vol.19,pp.329-340,1997.

[5] J. Sim, et al., "Characteristics of basalt fiber as a strengthening material for concrete structures," Composites: Part B Engineering vol. Vol. 36, pp. 504512,2005.

[6] E. G. Nawy, Fundamentals of High Strength High Performance Concrete. London, UK: Longman Group Limited,1996.

[7] A. Oner, et al., "An experimental study on strength development of concrete containing fly ash and optimum usage of fly ash in concrete," Cement and ConcreteResearchvol.Vol.35,pp.1165–1171,2005.

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[8] V.M.MalhotraandP.K.Mehta,HighPerformance,HighVolume Fly Ash Concrete: materials, mixture proportioning, properties, construction practice, and casehistories.,2nded.Ottawa,Canada:Supplementary CementingMaterialsforSustainableDevelopmentInc., OttawaCanada,2005.

[9] A.BilodeauandV.M.Malhotra,"High-VolumeFlyAsh System: Concrete Solution for Sustainable Development," ACI Materials Journal, vol. JanuaryFebruary2000,pp.41-50,2000.

[10] K. H. Obla, et al., "Properties of Concrete Containing Ultra-Fine Fly Ash," ACI MATERIALS JOURNAL, vol. Sept.-Oct.2003,pp.426-433,2003.

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