Factors Influencing The Microbial Calcium Carbonate Precipitation Performance In Sands

Abstract

Microbial induced calcium carbonate precipitation is relatively a new ground improvement technique for geotechnical engineers. This technique uses non-pathogenic organisms that are found naturally in soil environment to cement sand particles together at their contacts. This thesis describes the influence of various factors on cementation of MICP-treated soil catalyzed by bacteria and urease from an experimental study. Some of these factors include number of nutrient cycles, concentration of calcium chloride solutions, number of injections and particle size. Finally the objective of my research is to have a better understanding about the effects of various parameters on the biological cementation. Ottawa sand has been used for all the experiments that herein presented as it was used by many other researchers studying similar phenomena. Sporosarcina pasteurii (ATCC-6453), a urea producing microorganism was used for the bio-treatment of sand. The microorganisms were introduced to soil by suspending them in the urea solution and over time they were supplied with necessary nutrients via nutrient cycles through peristaltic pump and syringe. Scanning electron microscope examination was performed to study the microstructure of the soil samples over a range of curing periods for any cementitious bonds that may have formed.