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microbial-inspired self-healing of concrete cracks by sodium silicate-coated recycled concrete aggregates served as bacterial carrier

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Frontiers of Structural and Civil Engineering 2024年第1期18卷 14-29页

作者： Jing XU Xianzhi WANG Wu YAO Anna A.KULMINSKAYA Surendra P.SHAH Key Laboratory of Advanced Civil Engineering Materials(Ministry of Education) School of Materials Science and EngineeringTongji UniversityShanghai 201804China Petersburg Nuclear Physics Institute Named by B.P.Konstantinov of National Research Centre Kurchatov InstituteGatchina 188300Russia Center for Advanced Construction Materials University of Texas at ArlingtonArlingtonTX 76019USA

microbially induced carbonate precipitation(MICP)is a promising technique for the autonomous healing of concrete *** this study,the effect of pH on MICP was *** results indicate that the MICP process was inhibited when the pH was higher than *** vaterite and calcite were produced when the pH was*** concrete aggregates(RCA)coated with sodium silicate have been proposed as protective carriers for microbial healing *** the presence of the coated RCA resulted in a loss of the splitting tension strength of the concrete,the loaded healing agents were highly efficient in self-healing *** incorporated with 20%RCA loaded with healing agents exhibited the best self-healing *** the initial crack widths were between 0.3 and 0.4 mm,the 7-d mean healing rate was approximately 90%.At 28 d,the crack area filling ratio was 86.4%,while its water tightness recovery ratio was 74.4%and 29.8%,respectively,for rapid and slow *** study suggests that RCA coated with sodium silicate is an effective method for packaging microbial healing agents and has great potential for developing cost-effective self-healing concrete.

关键词： self-healing microbial-induced carbonate precipitation water uptake recycled concrete aggregate protective carrier

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Unconfined compressive strength of MICP and EICP treated sands subjected to cycles of wetting-drying,freezing-thawing and elevated temperature:Experimental and EPR modelling

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第5期15卷 1226-1247页

作者： Isaac Ahenkorah Mizanur Rahman Rajibul Karim Simon Beecham WSP Golder WA6003Australia UniSA STEM University of South AustraliaMawson LakesSA5095Australia

microbial-induced carbonate precipitation(MICP)and enzyme-induced carbonate precipitation(EICP)are two bio-cementation techniques,which are relatively new methods of ground *** both techniques share some similarities,they can exhibit different overall behaviours due to the differences in urease enzyme sources and treatment *** paper presented 40 unconfined compressive strength(UCS)tests of MICP and EICP treated sand specimens with similar average calcium carbonate(CaCO3)content subjected to cycles of wetting-drying(WD),freezing-thawing(FT)and elevated temperature(fire resistance test e FR and thermogravimetric analysis e TG).The average CaCO3 content after a certain number of WD or FT cycles(ACn)and their corresponding UCS(qn)reduced while the mass loss *** EICP treated sand specimens appeared to exhibit a lower resistance to WD and FT cycles than MICP treated specimens possibly due to the presence of unbonded or loosely bonded CaCO3 within the soil matrix,which was subsequently removed during the wetting(during WD)or thawing(during FT)*** test and TG analysis showed a significant loss of mass and reduction in CaCO3 content with increased temperatures,possibly due to the thermal decomposition of CaCO3.A complete deterioration of the MICP and EICP treated sand specimens was observed for temperatures above 600*** observed behaviours are complex and theoretical understanding is far behind to develop a constitutive model to predict ***,a multi-objective evolutionary genetic algorithm(GA)that deals with pseudo-polynomial structures,known as evolutionary polynomial regression(EPR),was used to seek three choices from millions of polynomial *** best EPR model produced an excellent prediction of qn with a minimum sum of squares error(SSE)of 2.392,mean squared error(MSE)of 0.075,root mean square error(RMSE)of 0.273 and a maximum coefficient of determination of 0.939.

关键词： Bio-cementation Enzyme-induced carbonate precipitation (EICP) microbial-induced carbonate precipitation (MICP) Calcium carbonate Urease enzyme

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Effects of nitrogen sources on MICP-related metabolic mechanism of Sporosarcina pasteurii and soil reinforcement

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第12期16卷 5147-5161页

作者： Shiyu Liu Xiaozhu Ding Peijian Song Lifeng Hu Zhou Hu Jin Yu Fangqiang Chang Fujian Research Center for Tunneling and Urban Underground Space Engineering Huaqiao UniversityXiamen361021ChinaNanchang Railway Tianhe Construction Co.Ltd.Nanchang330026China

Sporosarcina pasteurii(***)is widely used in microbial-induced carbonate precipitation(MICP)due to its high urease *** this paper,the effects of nutrients on the metabolic mechanism and mineralization ability of *** were studied by comparing the bacteria's growth,gene expression,and mineralized sand column under different nitrogen *** results showed that urea and soy peptone replacing the inorganic and organic nitrogen sources in ammonium sulfate-yeast extract(NH4-YE)medium can increase the urease activity of *** by 11.43%and 17.10%,*** the composite nitrogen source medium composed of urea and soy peptone,the urease activity of *** increased by 25.30%.The transcriptome sequencing results showed that the modified medium of urea and soy peptone could promote the basic life activity and metabolism of *** and is beneficial to urease *** them,the gene difference between the modified urea medium and the primary medium was more obvious,and the urea medium could promote the ATP synthase related to urease expression and urea *** unconfined compressive strength(UCS)of sand columns reinforced with *** cultured in Urea-YE,NH4-Soy peptone and Urea-Soy peptone increased by 27.6%,36%and 58.1%*** permeability decreased by 14.8%,20.1%and 81.3%respectively compared with that of sand columns reinforced with *** cultured in *** higher the urease activity of cultured bacteria,the more calcium carbonate produced after mineralization *** addition,the urease activity of bacteria has an influence on the morphology of calcite *** study can facilitate our understanding of optimizing the culture medium of *** and the artificial regulation of urease activity in the process of MICP.

关键词： Soil reinforcement microbial-induced carbonate precipitation Sporosarcina pasteurii Nitrogen sources Urease activity Transcriptome analysis

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