Role of biogeochemical interactions in biocementation of sandy soils

Biogenic calcite precipitation (BCP) is a sustainable method of stabilizing (i.e. cementing) loose sandy deposits and/or creating an impervious barrier within the soil mass. Among the multiple pathways known for biocementation, urea hydrolysis is considered to be the most efficient method of biochemically inducing calcite precipitation. While the impact of biogenic calcite on the engineering behaviour of sandy soils has been widely researched and extensively documented, the role of biochemical reactions and interactions between the microbes, biochemical products and geomaterials is seldom discussed. BCP is greatly influenced by the biosorption of bacterial cells on the soil grains and the reaction kinetics of urea hydrolysis. The mechanisms associated with the interaction of bacterial cells with the surface of soil grains and biogenic calcite act as a precursor to biocementation. The source of urease enzyme, their method of harvest and buffering capacity are significant parameters that aid in designing an efficient biocementation strategy to achieve the desired engineering behaviour. This chapter provides a critical commentary on existing literature on biocementation and insights into the methods and techniques from biochemistry and surface science, use of advanced instrumentation and molecular interaction theories that are central and necessary to analyze and design an effective biocementation implementation strategy.