A Stoichiometric Model for Biogeotechnical Soil Improvement

A stoichiometric model was developed for predicting the amount of carbonate precipitation and gas production from two different biogeotechnical soil improvement techniques: enzyme-induced hydrolysis of urea and microbial denitrification. Carbonate precipitation via hydrolysis of urea, or ureolysis, and via dissimilatory nitrate reduction, or denitrification, has been shown in laboratory testing to improve the shear strength and cyclic resistance of granular soils. Desaturation via denitrification has also shown the ability to improve cyclic resistance. For effective implementation of these techniques in the field, it is important to understand the material requirements necessary to achieve the desired degree of improvement. Therefore, a model for predicting carbonate precipitation and gas production from these techniques was developed using stoichiometry, thermodynamics, and microbial growth patterns and calibrated with laboratory test data. The model will facilitate the implementation of cost-effective, non-intrusive, and sustainable ground improvement.