Bio-cementation for the mitigation of surface erosion in loess slopes based on simulation experiment

Purpose Microbially induced calcite precipitation (MICP) has been shown to mitigate sand erosion; however, only few studies have used it on loess soils. Materials and methods This study used MICP to investigate the effects of this technology on the improvement of the surface erosion resistance of loess slopes. Polyvinyl acetate (PVAc) was added to the cementation solution to further increase slope stability. Results and discussion The obtained results showed that MICP treatment resulted in an improvement of erosion resistance and treatment with 3 L/m 2 bacterial suspension of Sporosarcina pasteuriiand 3 L/m 2 cementation solution (0.75 M of Ca(Ac) 2 and 0.75 M of urea) achieved the best erosion control and the highest surface strength. However, in rainfall simulation experiment, the eroded loss weight of loess soil in MICP-treated slopes still remained large. After adding PVAc to the cementation solution, the stability of the loess slope increased significantly and resulted in less soil loss after rainfall erosion and an increase in surface strength. With 60 g/L PVAc, the surface strength of the slope decreased by about 130 kPa compared with 40 g/L PVAc because of the thinner depth of cementation. The high erosion resistance of the slope with added PVAc could be attributed to (1) the network structure of PVAc to affix the calcium carbonate precipitation and (2) the stronger resistance to tension or shear force from PVAc. These results demonstrated that MICP-PVAc treatment significantly mitigated surface erosion of loess slopes, which presents promising potential for application in the field.