Relationship Between Pore Structure and Mechanical Properties of Ordinary Concrete Under Bending Fatigue

Abstract

Progressive macro damage of concrete under fatigue loading is caused by the change of its internal micro-meso properties such as pore structure. In this study, porosity, pore size distribution, and specific surface area of ordinary concrete at different fatigue stages were investigated using mercury intrusion, helium flow, and nitrogen adsorption (BET) methods. These properties changed with increasing loading cycles and could be taken as micro-meso damage parameters to evaluate macro fatigue damage of concrete. Test results showed that both porosity in mortar (mainly macro pores) and interface between mortar and coarse aggregates (interfacial cracks) developed at a similar rate. The corresponding residual bending fatigue strength and dynamic bending Young’s modulus were also obtained and their relationships with these micro-meso properties were established. The “intrinsic bending strength” and “intrinsic bending Young’s modulus” were predicted from these relationships.