EFFECT OF COARSE AGGREGATE GRADATION ON THE COMPRESSIVE STRENGTH OF A CONCRETE

Abstract

Thisprojectwasusedtoinvestigatetheeffectofcoarseaggregategradationonthecompressivestrengthofconcretefrom thethreesamplesofgranitesgotten from Agu-Awka round Aboutof20mm,10mm and 25mm coarse12aggregate,whichwaslefttodryandwastestedwithsieveanalysisasthepreliminarytestin orderto determinetheparticlesizedistribution.Theworkability(slump)oftheconcretewascarriedoutthroughaslumptestofwhichtheapparatususedareAnameltray,handtrowel,shovel,slumpcone,headpan,metallictape,tampingrodof25blowsoneachlayersofthreefillsandaweightbalance.Theweightofthesampleofthefineaggregateusedwas300kg,theweightofthesamplefor10mm coarseaggregateusedwas2000kg,theweightofthesampleforthe20mm coarseaggregateusedwas2000kg,theweightofsampleforthe25mm coarseaggregateusedwas2000g.Withthemixingratioofwatertocementratioof1:2:4.Theslumpsobtainedareintherangeof15mm to88mm.ThehighestslumpwasobtainedatconcreteA6whichis25mmand10mmcoarseaggregate.TheCompressivestrengthofsixcubesofconcretemadebyusingthreedifferent coarseaggregate(20mm and10mm),(10mm and25mm)inamixedproportion,thenthethirdsizewhichis25mm.TheCompressivestrengthofonefrom eachofthecubegroupsweremonitoredandcrushedattherangeof7daysand28daysbyaCompressivetestingmachine.TheCompressivestrengthoftheconcretewasdeterminedbytheautomaticCompressivetestingmachinewhenatthe7thdayofcuringatestloadof305.28KNwasconfirmedtocrushacubeof(10mmand20mm)concretewithastrengthof13.50N/MM^2,Atestloadof345.41KNwasconfirmedtocrushacubeof25mm atastrengthof15.35N/MM^2,Aloadof416.25KNwasconfirmedtocrushacubeof(10mmand25mm)ataCompressivestrengthof(18.50N/MM^2).Onthe28thdayofcuringatestloadof426.06KNwasconfirmedtocrushsecondcubeof10mmand20mm ataCompressivestrengthof18.93N/MM^2.Aloadof460.06(KN)wasconfirmedtocrushacubeof(25mm)ataCompressivestrengthof20.40N/MM^2.Andatestloadof573.75KNwasconfirmedtocrushedacubeof(10mm and25)ataCompressivestrengthof25.50N/MM^2.Inconclusion,itisnowmadetobeknownthroughtheresearchmadethattheCompressivestrengthofaconcretecanbedeterminedfrom theGradation(proportions)used and the smallerthe size ofan aggregate,the increase in thewater/cementratio which causes reduction effecton the Compressivestrengthoftheconcreteandthelargerinsizeofacoarseaggregatepresentinaconcretemix,theCompressivestrengthwhichisalsoinagreementwiththefindingsofVilane,B.RandSabelo(2016).Thatistosay,increaseinwaterratiobeyondtheproperproportion,AmateurcuringofconcreteandsmallerinsizeofacourseaggregateduringGradation,affecttheCompressivestrengthofaconcrete.