Surface roughness

Physics

Geology

Meteorology

Organic chemistry

Mathematics

Solid mechanics

Cementation (geology)

Statistics

Precipitation

Homogeneity (statistics)

Composite material

Mineralogy

Chemistry

Materials science

Phase (matter)

Cement

Dilatant

Acta Geotechnica

Microbially induced carbonate precipitation (MICP) has been actively investigated as a promising method to improve soil properties. A burning issue impeding its wide application is the severe spatial inhomogeneity of the CaCO3 distribution. Inspiring by the temperature sensitivity of the bacteria activity, a temperature-controlled one-phase MICP method is proposed consisting of two major steps: (1) grouting the specimen with the mixture of cementation and bacteria solutions in a low temperature; (2) inducing CaCO3 precipitation by exposing the specimen to room temperature. A series of experiments are conducted to demonstrate the advantages of the proposed method over the normal two-phase MICP method. Specimens treated with the proposed temperature-controlled method present higher CaCO3 contents with a roughly uniform distribution along the height of the specimen; the strength of those specimens are substantially improved with apparent dilatancy due to the effective bond network formed by the homogeneously distributed CaCO3 precipitation. SEM images indicate that the temperature-controlled method tends to form small crystals distributing uniformly on the grain surface, which may increase the roughness of the grain and the residual stress more effectively.

Homogeneity and mechanical behaviors of sands improved by a temperature-controlled one-phase MICP method