Effects of strain rate and confining pressure on compressive behavior of cement asphalt mortar

• We studied the effect of confining pressure on compressive behavior of CA mortar.
• The failure modes of CA mortar varied with different confining pressure.
• The mechanical properties of CA mortar increase linearly with confining pressure.
• The compressive behavior of CA mortar is sensitive to strain rate.
• A model to describe the stress–strain relationship of CA mortar is proposed.

A triaxial compressive test of Cement Asphalt Mortar (CA mortar) with a confining pressure ranging from 0 to 600 kPa was performed in this paper. The mechanical properties and experimental deviatoric stress–strain curve with respect to confining pressure were determined, and empirical equations of compressive strength and elastic modulus were obtained as a function of confining pressure. The effect of strain rate on the compressive behavior of CA mortar was also studied. Based on the experimental observation, a stress–strain model was developed to describe the softening and hardening characteristics of CA mortar subjected to confining pressure. The results showed that both compressive strength and elastic modulus increase monotonically with confining pressure, and are sensitive to strain rate. According to the reasonable agreement between predicted and experimental stress–strain curves, the proposed model is shown to be capable to CA mortar with and without confining pressure.