Experimental investigation on the mechanical and hydraulic properties of urease stabilized fine sand for fully permeable pavement

Abstract

A growing body of evidence suggests that the increase of permeability results in reduced strength and bearing capacity of subgrade. A new microbiological stabilizing method, known as microbial induced calcite precipitation (MICP), was induced into stabilization of the subgrade for fully permeable pavement in this study. This study explored the mechanical and hydraulic properties of unsaturated and saturated fine sand soil stabilized by MICP technology. Instead of bacteria, urease was directly induced into fine sand with pre-mixing method. The results indicated that saturated specimens obtained better moisture stability. Compared with cement stabilized soil, the compressive strength and resilient modulus of unsaturated urease stabilized soil were lower under the same CaCO3 or cement content. What stands out in this study is that the saturated urease stabilized soil was not sensitive to water and had relatively higher strength. In addition, the hydraulic conductivity of urease stabilized soil was significantly higher than that of cement stabilized soil. This study developed a potential subgrade improvement technology for possible application in fully permeable pavement. Urease stabilizing method could be used to help increase the strength and maintain a high hydraulic conductivity.