Evolution in Mechanical and Hydraulic Properties of Calcite-Cemented Sand Mediated by Biocatalyst

A grouting technique that utilizes precipitated calcite as cohesive material is presented. An enzyme of urease is used to enhance the rate and magnitude of the calcite precipitation. Evolutions in the mechanical and hydraulic properties of sand samples treated are examined through the unconfined compression and permeability tests, respectively. The grout is composed mainly of urease that bio-catalyzes the hydrolysis of urea into carbon dioxide and ammonia, urea, and calcium chloride solution. This method employs chemical reactions catalyzed by the enzyme, and ultimately acquires calcite precipitated within soils. The experimental results show that even a small percentage of calcite precipitation against soils of interest improves the strength drastically compared with that of untreated soil. The evolution in hydraulic conductivity measured is replicated by a flow simulator accounting for the chemical reactions. The predictions show good agreement with the actual measurements.