Field-scale bio-cementation tests to improve sands

TLDR

Microbially induced calcite precipitation (MICP) is a bio‑mediated cementation process that improves the geotechnical properties of soils through calcite precipitation at particle contacts. This study presents a field‑scale, surficial application of MICP to enhance erosion resistance of loose sand deposits and provide surface stabilisation for dust control and future re‑vegetation. Three test plots were treated with a bacterial culture and nutrient solutions at varying concentrations, a fourth plot served as control, and improvement was assessed to a depth of 40 cm using dynamic cone penetration testing and calcite measurements. The lowest‑concentration treatment produced a 2.5 cm stiff crust with enhanced erosion resistance, and DCP and calcite measurements showed improvement to about 28 cm depth, indicating that optimizing solutions could make MICP viable at larger scales.

Abstract

Microbially induced calcite precipitation (MICP) is a bio-mediated cementation process that improves the geotechnical properties of soils through the precipitation of calcite at soil particle contacts. This study presents a field-scale, surficial application of MICP to improve the erosion resistance of loose sand deposits and provide surface stabilisation for dust control and future re-vegetation. Three test plots were treated with a bacterial culture and nutrient solutions at varying concentrations, and a fourth test plot served as a control. Improvement was assessed to a depth of 40 cm using dynamic cone penetration (DCP) testing and calcite content measurements. The most improved test plot received the lowest concentrations of urea and calcium chloride and developed a stiff crust measuring 2·5 cm thick, which exhibited increased resistance to erosion. DCP testing and calcite content measurements indicated improvement to a depth of approximately 28 cm near the targeted depth of 30 cm. The results suggest that further optimisation of solutions and techniques could render MICP viable for larger-scale applications.