Abstract: Microbial induced calcite precipitation (MICP) technology is applied to the formation of in-situ bio-mineralization crust on the surface of desert, which enables floating dune to be semi-fixed and fixed, hinders wind erosion, and fundamentally blocks the source of sandstorm. Two bio-mineralization test plots (TP1 and TP3) were built using two different microbial strains on the Aeolian sand surface in Ulan Buh desert, Inner Mongolia Autonomous Region of China. The field-scale experiment methods and processes were designed to evaluate and analyze the strength of bio-mineralization crust and its long-term stability in the desert environment. Staphylococcus, extracted from local Aeolian sand, and Sporoscarcina pasteurii, a traditional bio-mineralized bacterium, were used to induce the formation of calcium carbonate crystals. Through penetration tests in site, the penetration resistance developed along the depth of bio-mineralization crust was recorded on the 7th, 14th, 28th, 60th and 210th day. The strength of bio-mineralization crust was converted according to the value of average penetration resistance at 2.0 cm of the crust. The variation of strength of bio-mineralization crust with mineralization time was summarized. From visual observation in site, the bio-mineralization crust began to form on the 4th day. The average thickness ranges from 2.0 cm to 2.5 cm on the 7th day, and the strength of bio-mineralization crust induced from Staphylococcus was 1.05 times than that of Sporoscarcina pasteurii. For the bio-mineralization crust TP3 induced from Sporoscarcina pasteurii after freeze-thaw cycles on the 210th day, the average thickness decreased from 0.7cm to 1.0cm, the strength was reduced by 19% and the content of calcium carbonate was reduced by 15%-30% compared with that on the 7th day. However, the strength of bio-mineralization crust TP1 induced from Staphylococcus on the 210th day was reduced only by 2%, which is a little less than that on the 7th day. MICP technology can be applied to the formation of in situ bio-mineralization crust in desert. The bio-mineralization crust developed from Staphylococcus has better strength performance and long-term stability in desert environment than that from Sporoscarcina pasteurii.

Key words: microbial induced calcite precipitation (MICP) technology, Staphylococcus, long-term stability, bio-mineralization crust, field-scale test