The role of bacterial urease activity on the uniformity of carbonate precipitation profiles of bio-treated coarse sand specimens

Abstract Protocols for microbially induced carbonate precipitation (MICP) have been extensively studied in the literature to optimise process with regard amount of injected chemicals, ratio urea calcium chloride, method injection and intervals, population bacteria, usually using fine- medium-grained poorly graded sands. This study assesses effect varying urease activities, which not systematically, densities bacteria on uniformity cementation very coarse sands (considered poor candidates treatment). A procedure producing desired activities was developed qPCR tests were conducted measure counts RNA Ure-C genes. Sand biocementaton experiments followed, showing that slower rates MICP reactions promote more effective uniform cementation. Lowering activity, particular, results progressively uniformly cemented samples it is proven be enough when its value less than 10 mmol/L/h. The work presented highlights importance activity controlling quality quantity cements.