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Theory of Microbial Carbonate Precipitation and Its Application in Restoration of Cement‐based Materials Defects
Author(s) -
Qian Chunxiang,
Wang Ruixing,
Cheng Liang,
Wang Jianyun
Publication year - 2010
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.201090156
Subject(s) - cement , chemistry , carbonate , compressive strength , chemical engineering , calcium carbonate , precipitation , mineralization (soil science) , extracellular polymeric substance , matrix (chemical analysis) , biofilm , mineralogy , composite material , chromatography , bacteria , materials science , organic chemistry , geology , paleontology , physics , meteorology , nitrogen , engineering
Abstract Bacterial induced carbonate mineralization has been demonstrated as a new potential method for restoration of limestones in historic buildings and monuments. We claim here the formation of calcium carbonate was controlled by extracellular polymeric substances (EPS) isolated from Bacillus pasteurii . The process of crystallization nucleation was accelerated in the presence of cells and inhibited in the presence of EPS. The CaCO 3 film deposited on cement paste surface was about 100 µm after 7 d treatment. The results of various restoring methods showed that higher decrease of water absorption of cement paste was gained in brushing application in the presence of agar, which could maintain urease with high activity in long term compared to spraying method. The coefficient of capillary suction of cement paste treated with brushing method was reduced by 90%. Mixed media consisted of sands, urea, Ca 2+ and concentrated biomass, was injected into artificial cracks of cement paste followed by continual nutrient supplement, and CaCO 3 particles were precipitated gradually between sands particles which were combined with cement matrix. The results showed that the compressive strength of recovered specimens was restored to 84%, which demonstrated that this kind of bio‐restoration method is effective in repairing surface defects of cement‐based materials.