A microscopic approach to rate effect on compressive strength of concrete

The enhancement of concrete strength under uniaxial dynamic compression is investigated in this paper. The influence of the microcrack density to the concrete compressive strength is also discussed. Based on the sliding crack model, the compressive strength is obtained by considering the interaction between microcracks using the Kachanov method. Both free water viscosity and inertia effect are included by considering their influences on the dynamic stress intensity factor of crack tip under linearly increasing load. The relationship between the dynamic strength increase factor and the strain rate is obtained. The comparison between the results by the model proposed in this paper and those by available experiments indicates a favorable agreement.