钙源对微生物矿化胶结砂土材料均匀性的影响OA北大核心CSTPCD

Microbially induced carbonate precipitation(MICP)technique is one of the promising methods that can improve the mechanical behaviors of the sand materials via the precipitated calcium carbonate crystals.However,the uniformity of bio-cemented sand materials is a vital problem and hinders the engineering applications of MICP technique.This study explores the effects of calcium chloride and calcium acetate on the MICP process and the uniformity of bio-cemented sand columns(3 cm in diameter and 11 cm in height,5 cm in diameter and 100 cm in height)treated one batch of MICP injection.The calcium carbonate content and unconfined compressive strength results of bio-cemented sand samples demonstrate that the calcium acetate can enhance the length of the cementation path,improve the calcium carbonate distribution along the grouting direction,and reduce the strength differences among the bio-cemented sand materials.Combining with the results of ammonium and calcium ion concentration in the solution environment,when the calcium acetate acts as the calcium source,the rate of MICP reaction is slower than that by calcium chloride,benefitting the transmission path of the undecomposed urea and the free calcium ions,thereby improving the uniformity of bio-cemented sand materials.