Experimental Study on the Influence of Different Factors on the Mechanical Properties of a Soil–Rock Mixture Solidified by Micro-Organisms

In this paper, we focus on the application of mechanical properties in a soil–rock mixture modified by microbial mineralization under the influence of different factors, including pH value, cementing solution concentration, and cementing time. Cementing fluids and samples with different pH values, calcium ion concentrations, and mineralization cementation were prepared. The process of urea hydrolysis MICP under different factors was studied. A solidified soil–rock mixture sample under triaxial compression was measured. Then, combined with scanning test methods, such as SEM and XRD, the influence of different factors on the mechanical strength and failure mode of the soil–rock mixture structure was analyzed from a microscopic point of view. The results show that a low concentration of cementing solution with a high concentration of bacteria liquid generated the highest calcium carbonate content and the strongest cementing ability. When the pH value of the cementation solution is six, the cementation effect between the pores is the best, and the deviatoric stress is stronger. When wet-curing samples, short or long curing time will adversely affect the strength of soil–rock mixture samples, the strongest curing and cementing ability is 5 days. The microscopic results show that the microbial mineralization technology fills the pores between the particles, and the interaction force between particles is enhanced to enhance the strength of the soil–rock mixture.