Strength and Kaolin Nucleation in Biotreated Coarse Sand

Abstract

Microbially induced carbonate precipitation (MICP) is an effective method for stabilizing sandy soil. However, this method is not effective for coarse sands. A kaolin-nucleating method was proposed in this study to improve the biotreatment of coarse sands. We comprehensively studied the effect of the kaolin concentration, the volume ratio of the bacterial solution to the cementation solution, the grouting interval between two slurry injections, and the bacterial density on the compressive strength of biotreated coarse sands. We found that the kaolin concentration and the bacterial density are positive factors for enhancing the compressive strength and there are also suitable values for the volume ratio of the bacterial solution to the cementation solution and the grouting interval to improve the biotreatment when other factors are specified. Interestingly, the biotreated condition for the specimen with the maximum strength was identical to that with the maximum ratio of the precipitate volume to the specimen void but different from that with the maximum calcium carbonate content.