Experimental study on the effect of grouting interval on microbial induced calcium carbonate precipitation

Abstract

Microbial induced calcium carbonate precipitation is a kind of environmentally friendly soil improvement technology. Microbial induced calcium carbonate precipitation reaction needs to enhance microorganism and nutrient solution containing urea and calcium salts. Different grouting intervals will get different curing effects.. In this paper, the effect of bio-cemented sand under different grouting time intervals was analyzed from the macroscopic physical and mechanical properties and micropore structures through the soil test and the electron microscope scanning test of the bio-cemented sand. The experimental results show that: with the increase of grouting time interval, the effect of bio-cemented sand was first increased and then decreased, and the 8h was the turning point of trend change. When the time interval was 8h, the permeability coefficient, water absorption, dry density, unconfined compression strength and calcium carbonate content reached 1.79E-04m/s, 18.88%, 1.67g/cm3, 0.90MPa and 3.49%, respectively. The scanning pictures show the calcium carbonate precipitation effectively bonded sand particles. The apparent pore content and the average pore diameter under the 8h of the time interval was 12.66% and 43.690 μm respectively, which was smaller than that of the others.