CHARACTERIZATION OF MICROCRACKING IN VERY EARLY AGE CONCRETE SUBJECTED TO ELEVATED TEMPERATURE BY AE

AE technique was used to characterize microcracking in concrete from the age of 1.5hrs, under temperature from 20 to 60 o C. Microcracks occurred considerably in the cooling period. Driving force induced by incompatibility of deformation between mortar and coarse aggregate. The tendency of tensile strength loss agreed with AE results. Damage in GGBFS concrete was severer than that in OPC concrete due to larger number of small microcracks. Concrete was deteriorated considerably under cyclic temperature. Mitigating measures by using LWA and coarse aggregate of suitable type and size were proposed.