Effects of cementation solution parameters on reinforcing silt by bio-cementation

Cementation solution has a great effect on soil reinforcement with microorganism. Taking marine silt as treatment soil, Sporosarcina pasteurii as microorganism, urea and calcium chloride as cementation solution, the effects of cementation solution parameters on the reinforcement were studied. The sample was effectively reinforced by premixing bacteria with soil followed by cementation solution percolation repeatedly. The effects of several parameters of cementation solution such as concentration, number of treatments, ratio and volume were studied through experiments. The results indicate that soil samples are stable in water when the concentration of the cementation solution is no less than 0.50 mol/L. The amount of precipitated CaCO3 and unconfined compression strength increase with the amount of the cementation solution. When the concentration reaches 1.50 mol/L, CaCO3 homogeneity and the peak strength decrease remarkably. Increasing the urea ratio in the cementation solution will bring no significant improvement to reinforcement. The reduction of the cementation solution volume of each treatment will worsen reinforcement, and then the volume should be not less than the volume of void. Results of experiments and SEM images indicate that the concentration of the cementation solution has a direct effect on the CaCO3 distribution and crystal size, thus affecting reinforcement strength. © 2021, Editorial Department of Journal of Southeast University. All right reserved.