Bacterial activity and cementation pattern in biostimulated MICPtreated sand-bentonite mixtures  

作　　者：Yu Zhang Xiangrui Xu Shiqi Liu Yijie Wang Juan Du Ningjun Jiang 

机构地区：[1]Institute of Geotechnical Engineering,School of Transportation,Southeast University,Nanjing,211189,China [2]Jiangsu Key Laboratory of Low Carbon and Sustainable Geotechnical Engineering,Nanjing,211189,China [3]Department of Civil and Environmental Engineering,The Hong Kong Polytechnic University,Hung Hom,Hong Kong,China [4]College of Civil Engineering and Architecture,Hainan University,Haikou,570228,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2024年第12期5121-5134,共14页岩石力学与岩土工程学报（英文）

基　　金：supported by the Key R&D Program Social Development Project of Jiangsu Province(Grant No.BE2023800);the Natural Science Foundation of China(Grant No.42377166);the National Key R&D Program of China(Grant No.2023YFC3709600)。

摘　　要：The application of microbially induced carbonate precipitation(MICP)in clayey soils has attracted much attention,and many studies used clay as an additive to enhance microbial mineralization efficiency in sandy soils.Within the sand-clay-bacteria-calcite system,the property and content of clay play crucial roles in affecting bacterial growth and calcite formation.More important,bentonite is particularly sensitive to changes in the geochemical environment.In this study,the sand-bentonite mixtures were treated by biostimulated MICP,aiming to provide insights into the behavior of this system.The bacterial activity and cementation pattern at different bentonite contents were evaluated through a series of tests such as enrichment tests,unconfined compressive strength(UCS)tests,cementation content measurements,mercury intrusion porosimetry(MIP)tests,scanning electron microscopy(SEM)observations,and energy dispersive X-ray spectroscopy(EDS)analyses.The findings showed that the bentonite presence promoted the enrichment of indigenous ureolytic bacteria,with lower bentonite levels enhancing ureolytic activity.Macroscopic and microscopic characterization indicated that the bentonite-coating sand structure was more conducive to the formation of large-sized calcite crystals capable of cementing soil particles compared to sand-supported and bentonite-supported structures.Additionally,excessive calcium ions(Ca^(2+))concentrations in the cementitious solution would lead to predominant calcite deposition on soil particle surfaces,contributing minimally to strength improvement.

关 键 词：Microbially induced carbonate precipitation (MICP) BIOSTIMULATION Sand-clay mixtures Bacterial activity Cementation pattern 

分 类 号：TU441.33[建筑科学—岩土工程]