Bio-cementation of sandy soil at different relative density

Abstract

Enzyme-induced carbonate precipitation (EICP) is a bio-inspired technique used to improve the geotechnical properties of a variety of soils. The process of EICP is triggered by plant-derived urease enzyme in the presence of calcium ion to produce calcium carbonate within the soil matrix. This study aims to evaluate the influence of relative density on the strength of bio-cemented sandy soil. The mix and compact method was adopted to treat the sandy soil. Soil samples were prepared at three different relative density (loose, medium, and dense states) and three concentrations of cementation reagent (0.25, 0.5 and 1.0 M). The unconfined compressive strength tests, calcium carbonate content and FESEM analysis were carried out on the treated soil sample. The findings showed that the unconfined compressive strength (UCS) increased with higher relative density and concentration of cementation reagent (CCR). For instance, at 0.25 M UCS value of 98, 141 and 160 kPa were obtained at loose, medium and dense state, respectively. The shows that the increase in strength of bio-cemented sandy soil was not only attributed to the calcite content formed within the soil but also the extent of the denseness of the soil. The microstructural morphology further confirms the formation of CaCO3, which is partly responsible for the general improvement of strength of the sandy soil.