Autogenous shrinkage of high-performance concrete containing fly ash

Abstract

This paper focuses on the effect of fly ash on autogenous shrinkage of high-performance concrete (HPC). The stresses induced by autogenous shrinkage were calculated using finite element method and a model for predicting autogenous shrinkage including the effect of fly ash was proposed. Test results show that autogenous shrinkage of HPC with water-to-cementitious materials ratio (w/cm) of equal to or less than 0·35 developed more rapidly than that of normal-strength concrete (NSC) with a w/cm of 0·50. For HPC with the same w/cm but containing fly ash, autogenous shrinkage decreased – the higher the fly ash replacement percentage, the lower the level of autogenous shrinkage. Numerical analysis results show that the tensile stress induced by autogenous shrinkage may cause early-age cracking in HPC. In conclusion, although partial replacement of cement by fly ash could effectively reduce autogenous shrinkage of HPC, incorporating fly ash only might not prevent early-age cracking.