Abstract: In order to investigate the damage characteristics of the splitting and tensile process of orthoconcrete, a three-dimensional five-phase mesoscopic model was established, which included mortar, aggregates, the interfacial transition zone of the outer surface of reference aggregates, the interfacial transition zone of the outer surface of post-filling aggregate and pores. The effect of mesh size on the final failure mode and stress-strain relationship of concrete were studied, and the effects of coarse aggregate filling rate and aggregate particle size on the splitting tensile properties of concrete were analyzed. The results show that when the mesh size is 1.0 mm, the model can effectively simulate the crack morphology and stress-strain relationship of splitting tensile damage of orthoconcrete. The splitting tensile strength of orthoconcrete increases first and then decreases with the increase of filling rate, and reaches the maximum when the post-filling rate is 20% (volume fraction). When the filling rate is constant, the splitting tensile strength of orthoconcrete with 16~31.5 mm filling aggregate is higher. The comparison between simulation and experimental results reveal low the error value, which indicates that the proposed mesoscopic model can successfully simulate the damage behavior of orthoconcrete under splitting tensile stress.

Key words: orthoconcrete, splitting tensile, mesoscopic model, post-filling rate, crack propagation