A Study on Curing Sensitivity of Concrete with Different Cement Types and Mineral Admixtures

Abstract

This research is emphasized on the effect of curing sensitivity on compressive strength ofconcrete with different types of cement and mineral admixtures. Concretes with binary and ternary bindersof Portland cement, fly ash and limestone powder were produced to investigate their curing sensitivity byconsidering compressive strength as the indicator. For cement concrete, ordinary Portland cement types 1,3 and 5 conformed to ASTM C150 were used to study the effect of fineness and chemical composition ofcement. Two types of fly ash which conform to EIT 1014 type 2a (CaO < 10%) and type 2b (CaO > 10%)were used to investigate the effect of fly ash types. Two series of concrete with water to binder ratios byweight (w/b) of 0.35 and 0.55 were produced for compressive strength. The specimens were subjectedto two curing conditions which are continuously water-cured and continuously air-cured. The curingsensitivity of concrete on compressive strength was evaluated by using the curing sensitivity index(CSI) which is the percentage difference between compressive strength of concrete that is continuouslywater-cured and that of continuously air-cured concrete. The higher curing sensitivity index means concreteis more sensitive to curing. It was found from the test results that in case of cement concrete, the curingsensitivity of concrete with Portland cement type 3 was lowest compared to the other types of cement whileconcrete with Portland cement type 5 was the most sensitive to curing. Cement-fly ash concrete is moresensitive to curing than the cement concrete. The curing sensitivity of concrete with fly ash type 2a washigher than concrete with fly ash type 2b. The use of limestone powder reduced the curing sensitivity ofcement only and cement-fly ash concrete.

Keywords : Multiple Binders / Sensitive to Curing / Compressive Strength / Fly Ash / LimestonePowder