Numerical modeling of biocemented soil behavior

Abstract

Soils are unconsolidated and heterogeneous materials that induce numerous geotechnical challenges due to poor bearing capacity, uniform and differential settlement of building, seepage, scouring, and erosion. Recently developed microbially induced calcite precipitation (MICP) technique is an environmentally friendly and sustainable technique that works on nature’s concept of forming rocks and minerals. The natural mineral formation is a quiet slow process that can be expedited by adding a sufficient amount of nutrients to the soil including urea and calcium sources to form calcite crystals between soil grains. However, the application of MICP requires a proper understanding of the kinetics of biogeochemical reactions in the urea hydrolysis and biocementation process. The study includes numerical modeling of precipitation kinetics of calcium carbonate with time and distance in granular soil media, including the factors affecting the rate of urea hydrolysis (i.e., pH and electrical conductivity). The laboratory investigations were also carried out on sand using Sporosarcina pasteurii strain with two different cementation media concentrations, i.e., 0.25 and 0.50 M. The experiments were conducted and analyzed after 10 and 20 days of biotreatment for calcite precipitation using calcimeter. The presence of calcite between sand grains was identified by SEM images. The predicted results were found in concurrence with experimental results, which proves the validation of the numerical model. © 2021 Elsevier Inc. All rights reserved.