Effect of silica powder on microbial-induced carbonate precipitation improvement of medium-coarse sand

Microbial-induced calcium carbonate precipitation (MICP) is a green and sustainable technique for changing or improving the physical and mechanical properties of soils. Silica powder has good pozzolanic activity and filling ability. In this paper, silica powder and MICP technology are combined to improve the efficiency of microbial-induced calcium carbonate precipitation by utilizing the good activity of silica powder, so as to study the influence of silica powder on the physical and mechanical properties of bio-treated medium-coarse soil. The bio-treated samples were tested and evaluated in terms of bacterial retention capacity, calcium carbonate precipitation, microstructure, unconfined compressive strength (UCS), permeability, and durability. It was found that with the increase of silica powder content, the bacterial activity retention rate increased, the calcium carbonate content increased and the UCS increased, the permeability decreased significantly, the durability improved, but the water resistance and water absorption ability did not change significantly. Overall, because the silica powder enhances the performance of MICP treated sand, the waste silica powder can be effectively reused in the MICP technology.