Volume 31, No. 04, Month OCTOBER, Year 2020, Pages 33 - 46

Strength, porosity,and resistivity of coarse recycled concrete aggregateself-compacting concrete containing fly ash

Pongpol Ud-ai, Veera Horsakulthai

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This article wasa study of the possibility of using recyclable waste concrete in high strength self-compacting concrete.The waste concrete wascylindrical specimens with 150 mm diameter and 300 mm height, and 150 mm cubes which wereaged 1-2 years. The waste concretewascrushedinto a 20 mm maximum nominal size touse as a coarse aggregate. Self-compacting concrete with water to binder ratio of 0.35 was used as controlledconcrete (PC), in which the target compressive strength of 100 mm cubeswas 70 MPa at the age of 28 days. The PCconcretemixture was replaced crushed limestone with crushed recycled concrete aggregate, and the cement was partially replaced by class C fly ash at the dosage of 0%, 20%, 40%, and 60% by weight of the binder to produce concrete (CA, 20FA, 40FA, and 60FAconcrete, respectively).The slump flow was controlledin the range of 650-750 mm.The compressive strength, porosity, electrical resistivity, and non-steady state chloride migration wereinvestigated.From the experimental results, it was found that thecompressive strength ofCAconcretewaslower than that ofPCcontrolledconcrete but higher than the target compressive strength. The CA concrete had highertheporosity andthechloride diffusion coefficient and lower the electrical resistivity than that of PC controlledconcrete at the age of 28 days.The compressive strength of concrete containing fly ash was higher than the target compressive strength at the age of 90 days, except the 20FA concrete was higher at the age of 28 days. The chloride penetration resistance of concrete containing fly ash was higherthan that of PC control concrete. The tendencyof the chloride penetration resistanceincreasedwith containing the fly ash increased at the age of 90 days.


recycled concrete,self-compacting concrete, fly ash, compressive strength, porosity, resistivity, chloride diffusion.


Published by : The Engineering Institute of Thailand Under H.M. The King's Patronage
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