Surficial Soil Stabilization against Water-Induced Erosion Using Polymer-Modified Microbially Induced Carbonate Precipitation

Abstract

Microbially induced carbonate precipitation (MICP)–based biomediated soil improvement methods have been extensively studied recently due to their versatility, potential environmental sustainability, and potential low cost. However, an efficient MICP-based treatment method specifically designed for surficial soil stabilization against water-induced erosion is still urgently needed. This paper presents a preliminary experimental study on the application of a new polymer-modified MICP treatment for surficial soil stabilization to mitigate water-induced erosion. In the proposed method, the cementation solution for MICP is prepared in a water solution of polyvinyl alcohol (PVA) instead of water alone. Comparative tests are conducted to verify that the PVA-modified cementation solution provides a suitable environment for MICP, as well as to optimize the concentrations of cementation media used in the new method. The proposed method is then applied for bench-scale surficial stabilization of Ottawa sand. The performance of the surficial treatment is demonstrated by flume erosion tests, and the erodibility of the treated sand is evaluated more precisely using an erosion function apparatus (EFA). The experimental results show that the viscous polymer solution anchors the bacteria and cementation media in surficial regions and promotes the precipitation of calcium carbonate. Such a treatment results in a uniform soil crust in the surficial region and reduces the erodibility of sands. The critical shear stress of the treated sand is over 5 times higher than that of untreated sand as demonstrated by the EFA tests.