Biomediated control of colloidal silica grouting using microbial fermentation

Area of Science:

• Geotechnical Engineering
• Microbial Engineering
• Materials Science

Background:

• Colloidal silica grouting stabilizes soils and reduces hydraulic conductivity but faces challenges in controlling gelation rates and monitoring.
• Conventional methods rely on chemical accelerants, which can be unreliable under varying subsurface conditions.

Purpose of the Study:

• To propose and investigate a biomediated soil improvement process using fermentative microorganisms to control colloidal silica gelation.
• To assess the effectiveness of microbial enrichment and geochemical changes in mediating silica gel formation.
• To explore new monitoring approaches for microbial activity and gelation.

Main Methods:

• Enrichment of glucose-fermenting microorganisms in natural sands.
• Batch experiments to assess pH reduction and microbial mediation of gelation.
• Soil column experiments to evaluate monitoring techniques (chemical, hydraulic, geophysical) and engineering improvements.

Main Results:

• Fermentative microorganisms were successfully enriched to mediate silica gel formation without chemical accelerants.
• Microbial activity induced necessary geochemical changes (pH reduction, ionic strength increase) for gelation.
• Comparable engineering enhancements to conventional grouting were achieved, with new monitoring possibilities.

Conclusions:

• Biomediated colloidal silica grouting offers a more reliable and controllable alternative to conventional methods.
• This approach enables effective ground improvement and opens avenues for advanced in-situ monitoring.
• The findings advance sustainable and efficient geotechnical engineering solutions.