Urea supply control in microbial carbonate precipitation to effectively fill pores of concrete. (6th December 2021)

• Record Type: Journal Article
• Authors: Qin, Jinyi; Qin, Qingyang; Li, Xiaoguang; Xue, Jiaxin; Wang, Ruiqi; Zhang, Qian; Wang, Panqi; Guo, Zhizhong; Gong, Yifan
• Is Part Of: Construction & building materials. Volume 310(2021)
• Publication Date: 2021-12-06
• Subjects: MICP microbially induced calcite precipitation -- CFU colony-forming unit -- R2A Reasoner's 2A -- RNA ribonucleic acid -- BLAST Basic Local Alignment Search Tool -- OD optical density -- LB lysogeny broth -- SI Supporting Information -- HPLC high-performance liquid chromatography -- 16S rRNA 16S ribosomal ribonucleic acid -- ATP adenosine triphosphate; Bacillus sp. -- Growth rate -- Electron-transfer rate -- CaCO3 -- Urease -- Microbial; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2021.125123
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphical abstract: Highlights: MICP reduced porosity to 1.4%, and the mortar became denser. When Bacillus sp. was fed with 0.15 mol/L urea, the growth rate and urease activity reached 0.22 h −1 and 0.12 mg g -1 h −1 . For a urea supply > 0.15 mol/L, the conversion efficiency of MICP followed an exponential law. The electron transfer rate of MICP was 6.6 × 10 -6 cm s −1 . Abstract: In cement-based cementitious materials, high-porosity areas tend to expand microcracks. To counter this problem, microbially induced calcite precipitation (MICP) was suggested to fill the pores. However, it is unclear how to control the supply of urea to increase the MICP efficiency of Bacillus sp. Therefore, in this study, the microbial growth rate, urease activity, and urea-to-carbonate conversion efficiency were determined under different urea concentrations. When the urea concentration was 0.15 mol/L, the growth rate was 0.22 h −1, the cell number reached 4 × 10 9 colony-forming units (CFUs) mL −1, and the urease activity was approximately 0.12 mg g -1 h −1 . Additionally, the conversion efficiency reached 40%, following the rule of 0.51 + 0.08 e 0.5x . The electron-transfer rate of MICP measured via cyclic voltammetry was 6.6 × 10 -6 cm s −1 . It is based on nutrients, Bacillus sp., and urea and aims to develop a self-healing coating by reducing the porosity and improving its apparent impermeability.