Strength characteristics and microstructure of hooked-end steel fiber reinforced concrete containing fly ash, bottom ash and their combination

Abstract

The paper presents the effect of fly ash (FA), bottom ash (BA), and their combination on the age-dependent strength characteristics and microstructure of hooked-end steel fiber reinforced concrete (SFRC). High volumes of FA and BA (25% and 50%) were used as partial replacement of cement and fine aggregate, respectively. The fiber volume fractions of 0.5% and 1.5% were used. The compressive and splitting tensile strength of concrete was determined up to 90 days. It is found that the utilization of BA and FA slows down the strength gain but attains strength comparable with plain concrete at later ages, either with or without steel fibers. The increase in strength of fiber reinforced concrete due to the increase in the percentage of steel fibers is affected by the shape of the test specimen with the cylinders giving more enhancement than the cubes. The experimental results are validated with the microstructure analysis by using scanning electron microscopy. Semi-empirical mathematical models are developed for predicting the age-dependent compressive and splitting tensile strength of SFRC.