title: Bio-grout based on microbially induced sand solidification by means of asparaginase activity.
abstract: Bio-grout, a new ground improvement method, has been recently developed to improve the mechanical properties, decrease the permeability of porous materials, reinforce or repair cementitious materials and modify the properties of soil or sand. Bio-grout production depends on microbially induced calcite precipitation (MICP), which is driven mainly by an enzyme, urease. However, urease-based MICP process produces excessive ammonia, in addition to secondary pollution generated by urea that is used as substrate in it. In the present study, we reported asparaginase-based MICP process for sand bio-grout development using Bacillus megaterium, and results were also compared with urease-based bio-grouts. The asparaginase activity led to significantly less ammonia production compared to urease without compromising with desired properties of a novel grout. The UCS of bio-grout was obtained at 980 kPa, while the permeability was decreased substantially. The mineralogical composition of precipitated substance was identified as calcite using XRD and the crystal morphology was observed under SEM. The mass percentage of calcite in bio-grout was calculated by thermogravimetric analysis and XCT verified calcite precipitation in it. The results confirmed that biocalcification by means of bacterial asparaginase is a potential solution for geotechnical problems. The asparaginase-based MICP process could be of wider acceptance in future.
authors.affiliation: School of Ecological and Environmental Sciences, East China Normal University Shanghai 200241, China.
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.
authors.forename: Qing-Long
authors.initials: QL
authors.lastname: Fu
authors.affiliation: School of Ecological and Environmental Sciences, East China Normal University Shanghai 200241, China.
authors.forename: Qiuzhuo
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: School of Ecological and Environmental Sciences, East China Normal University Shanghai 200241, China.
authors.forename: Varenyam
authors.initials: V
authors.lastname: Achal
authors.affiliation: Faculty of Engineering, Hokkaido University, Sapporo 0608628, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Kawasaki
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001215:Asparaginase / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology; D002119:Calcium Carbonate / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013818:Thermogravimetry; D014057:Tomography, X-Ray Computed; D014510:Urease / Q000378:metabolism
chemical_list: D012822:Silicon Dioxide; D000641:Ammonia; D001215:Asparaginase; D014510:Urease; D002119:Calcium Carbonate