Biologically Inspired Silicification Process for Improving Mechanical Properties of Sand

Abstract

A new type of ground treatment method is developed to improve the engineering properties of coarse-grained soils. By using biochemical concepts derived from recent discoveries into how organisms produce silicified skeletons, a silicification process is reported that offers environmental and physical advantages over some traditional methods by using nontoxic, commercially available components with a low potential for adverse environmental effects. Silicification begins by first pretreating the soil with a commercially available cationic polyelectrolyte, which is then followed by injecting a mixture of commercial sodium silicate and buffer. The silicification solutions have a pH of 5.0–5.5, weakly acidic values that are within the range of surface soil environments in temperate weathering regions. Gel time is regulated by the sodium silicate or polyelectrolyte concentration. The compressive strengths are measured as a function of polyelectrolyte type and concentration by using samples of Ottawa