Influence of Different Particle Size and Rock Block Proportion on Microbial-Solidified Soil–Rock Mixture

This paper focuses on the influencing factors of MICP solidification of soil–rock mixture. After selecting the best soil–rock ratio through screening, the MICP process is tested from two aspects of rock content and particle size. The results show that the soil–rock mixture is not a uniform carrier of the medium, and the force on the surface of the sample is not uniform. With the increase in stress load, the stress–strain curve shows a sawtooth upward trend and peak value. The microbial cemented soil–rock mixture had a particle size of 0.2–0.4 cm and 0.4–0.6 cm under the rock block proportion of 50%. The unconfined compressive strength of the microbial cemented soil–rock mixture with a rock particle size of 0.6–0.9 cm reaches the highest at 60% rock block proportion. When the rock content is 20–50%, the unconfined compressive strength decreases with the increase in particle size. When the rock content is 60%, the value of unconfined compressive strength first decreases and then increases with the increase in particle size; both SEM and XRD test results proved that Sporosarcina pasteurii could effectively induce the formation of calcium carbonate and crystallizes at the pores of the particles to improve the mechanical properties of the soil.