Difference in dynamic direct tensile failure mechanism between homogeneous mortar and three-dimensional mesoscopic concrete based on the split Hopkinson tension bar

At the mesoscale, concrete is considered a three-phase composite material comprising stone, mortar, and the interfacial transition zone. Even though mortar is an important component of concrete, its material parameters have not been determined systematically, and they are often modeled by assuming that they are weaker versions of the concrete parameters. Therefore, accurately describing the role of mortar in concrete and the failure mechanism of concrete is difficult. The quasi-static and dynamic direct tensile tests were performed to obtain the stress–strain curves and failure modes of mortar specimens and to establish a formula describing the mortar strain-rate effect. Numerical simulations were then performed using the improved Karagozian and Case concrete models, and the obtained experimental data to clarify the differences in the failure mechanisms of mortar and concrete under dynamic tensile loads. Results showed that concrete had a higher tensile strength but a lower strain-rate effect than mortar. This paper provides an important contribution to study the failure analysis of concrete structures under dynamic loads.