Fatigue performance of composite concrete structure specimen (CCS) in flexure

Abstract

The paper presents a study on the fatigue behavior of composite concrete specimen (CCS). An experimental program was conducted to obtain the fatigue-behavior of CCS at various stress ratios. Fifty-six CCS specimens of size were tested under four-point flexural fatigue loading. To evaluate the mechanical properties of the interface between CA mortar and concrete materials, a surface analysis technique of scanning electron microscopy (SEM) observation was used in this study. Parallel with the SEM observations, the pore size distribution of CA mortar was studied by using BJH method. It is found that there exist obvious differences of flexural fatigue behavior between CCS and plain concrete specimens. According to the theory of material mechanics, the formula of dynamic elastic modulus in flexure is deduced. Based on the experimental results, the formula of dynamic elastic modulus and analysis of fatigue strain, the fatigue cumulative damage evolution equation is proposed.