Strength characteristics of biomimetic carbonate precipitation (BCP) treated mortar under cyclic loading

Abstract

L-Aspartic acid (L-Asp) has the potential to mediate the crystal form of calcium carbonate, and biomimetic carbonate precipitation (BCP) with L-Asp as the crystal modifier has been proposed for green mortar. However, the cyclic properties of BCP-treated mortar are rarely studied. In this study, the direct shear test was first performed to prove the ability of BCP treatment in improving the shear strength, friction angle, and cohesion of sand. It shows that higher normal stress can promote the pre-peak shear shrinkage of the specimen, while inhibiting the development of post-peak shear dilation. Then, the pre-peak cyclic shear test was conducted under different normal stresses, and the cyclic response of BCP-treated mortar with different number of loading cycles was investigated. The phenomenon of shear softening was observed, and the stress-strain behavior of the specimen was further studied. Finally, the specimens after cyclic loading were prepared for the direct shear test again to examine their post-cyclic properties. Results show that the specimen with more loading cycles has lower post-cyclic shear strength, while high normal stress can alleviate the decrease in shear strength after cyclic loading. With the increase in cyclic numbers, the cohesion of the specimen decreases, but the friction angle varies slightly. This study is expected to provide a deeper understanding on the shear response of BCP-treated mortar with cyclic loading.