Enzyme Induced Calcite Precipitation (EICP) to strengthen the ability of anti-wind erosion of earthen archaeological sites

The issue of soil erosion remains open so far although it has been researched for almost a century. Soil erosion also is the main damage type of earthen archaeological sites along the Silk Road in China. In recent years, Microbially Induced Calcite Precipitation (MICP), as an emerging and innovative technique has drawn more and more attention and been studied extensively in the field of soil improvement. It involves the process of calcite precipitation via ureolysis. In this paper, a new and simplified soil improvement technique, named Enzyme Induced Calcite Precipitation (EICP) is proposed. Urease, an enzyme that catalyzes the hydrolysis of urea, which is also the product of microorganism (i.e. Bacillus pasteurii) and Jack Bean was used directly in the calcite precipitation process in order to improve the anti-wind erosion ability of soil. Soil samples were collected from Xiaguanying ancient city, a rammed earth building, which has a history of more than one thousand years. A series of tunnel tests were conducted to evaluate the performance of Enzyme Induced Calcite Precipitation (EICP). The tests results showed that Enzyme Induced Calcite Precipitation (EICP) could improve the anti-wind erosion ability and strength of soil significantly. Our findings further suggest there is a good potential use of the Enzyme Induced Calcite Precipitation (EICP) process in the conservation of earthen archaeological sites.