Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Study on the influence of magnesium/calcium ratios on bio-cemented sandy soils
https://orcid.org/http://orcid.org/0000-0001-6234-3023
Microbially induced carbonate precipitation (MICP) has been extensively studied as a promising technique for soil stabilization. However, the heterogeneity in bio-cementation always hampers the application of MICP. Seawater contains more magnesium ions (Mg2+) than calcium ions (Ca2+) and using magnesium for bio-cementation might be more cost-effective in coastal cities. In this study, the microbially induced magnesium and calcium precipitation (MIMCP) treatment was proposed to solve the problem of heterogeneity, where the urea-magnesium-calcium solution was used as the cementation solution with various Mg2+/Ca2+ ratios. The influences of Mg2+/Ca2+ ratios on pH, bio-flocculation, and chemical conversion efficiency were studied. The sand bio-cementation tests were subsequently conducted to compare the treatment effects with different Mg2+/Ca2+ ratios. Results showed that the increase in Mg2+/Ca2+ ratios resulted in lower pH levels and smaller percentages of bio-flocculation. The higher Mg2+/Ca2+ ratio also provided a longer lag period, regardless of biomass concentrations; however, the chemical conversion efficiency decreased. Furthermore, the increased Mg2+/Ca2+ ratios resulted in a small difference in UCS and contents of precipitation at different parts of bio-cemented soils, achieving better homogeneity in bio-cementation. However, the strength significantly decreased at an Mg2+ concentration over 0.8 M due to much smaller contents of precipitation. In addition, with increased Mg2+/Ca2+ ratios, more aragonite in calcium precipitation was produced. The proposed MIMCP method in this study was significant to improve the homogeneity of bio-cemented soil in practical engineering applications.
Study on the influence of magnesium/calcium ratios on bio-cemented sandy soils
https://orcid.org/http://orcid.org/0000-0001-6234-3023
Microbially induced carbonate precipitation (MICP) has been extensively studied as a promising technique for soil stabilization. However, the heterogeneity in bio-cementation always hampers the application of MICP. Seawater contains more magnesium ions (Mg2+) than calcium ions (Ca2+) and using magnesium for bio-cementation might be more cost-effective in coastal cities. In this study, the microbially induced magnesium and calcium precipitation (MIMCP) treatment was proposed to solve the problem of heterogeneity, where the urea-magnesium-calcium solution was used as the cementation solution with various Mg2+/Ca2+ ratios. The influences of Mg2+/Ca2+ ratios on pH, bio-flocculation, and chemical conversion efficiency were studied. The sand bio-cementation tests were subsequently conducted to compare the treatment effects with different Mg2+/Ca2+ ratios. Results showed that the increase in Mg2+/Ca2+ ratios resulted in lower pH levels and smaller percentages of bio-flocculation. The higher Mg2+/Ca2+ ratio also provided a longer lag period, regardless of biomass concentrations; however, the chemical conversion efficiency decreased. Furthermore, the increased Mg2+/Ca2+ ratios resulted in a small difference in UCS and contents of precipitation at different parts of bio-cemented soils, achieving better homogeneity in bio-cementation. However, the strength significantly decreased at an Mg2+ concentration over 0.8 M due to much smaller contents of precipitation. In addition, with increased Mg2+/Ca2+ ratios, more aragonite in calcium precipitation was produced. The proposed MIMCP method in this study was significant to improve the homogeneity of bio-cemented soil in practical engineering applications.
Study on the influence of magnesium/calcium ratios on bio-cemented sandy soils
https://orcid.org/http://orcid.org/0000-0001-6234-3023
Microbially induced carbonate precipitation (MICP) has been extensively studied as a promising technique for soil stabilization. However, the heterogeneity in bio-cementation always hampers the application of MICP. Seawater contains more magnesium ions (Mg2+) than calcium ions (Ca2+) and using magnesium for bio-cementation might be more cost-effective in coastal cities. In this study, the microbially induced magnesium and calcium precipitation (MIMCP) treatment was proposed to solve the problem of heterogeneity, where the urea-magnesium-calcium solution was used as the cementation solution with various Mg2+/Ca2+ ratios. The influences of Mg2+/Ca2+ ratios on pH, bio-flocculation, and chemical conversion efficiency were studied. The sand bio-cementation tests were subsequently conducted to compare the treatment effects with different Mg2+/Ca2+ ratios. Results showed that the increase in Mg2+/Ca2+ ratios resulted in lower pH levels and smaller percentages of bio-flocculation. The higher Mg2+/Ca2+ ratio also provided a longer lag period, regardless of biomass concentrations; however, the chemical conversion efficiency decreased. Furthermore, the increased Mg2+/Ca2+ ratios resulted in a small difference in UCS and contents of precipitation at different parts of bio-cemented soils, achieving better homogeneity in bio-cementation. However, the strength significantly decreased at an Mg2+ concentration over 0.8 M due to much smaller contents of precipitation. In addition, with increased Mg2+/Ca2+ ratios, more aragonite in calcium precipitation was produced. The proposed MIMCP method in this study was significant to improve the homogeneity of bio-cemented soil in practical engineering applications.
Study on the influence of magnesium/calcium ratios on bio-cemented sandy soils
Acta Geotech.
Sun, Xiaohao (Autor:in) / Miao, Linchang (Autor:in) / Wang, Hengxing (Autor:in) / Cao, Ziming (Autor:in) / Wu, Linyu (Autor:in) / Chu, Jian (Autor:in)
Acta Geotechnica ; 19 ; 5449-5464
01.08.2024
16 pages
Aufsatz (Zeitschrift)
Elektronische Ressource
Englisch
Bio-cementation , Ca<sup>2+</sup> ratios , Homogeneity , Mg<sup>2+</sup> , Sand stabilization , UCS Engineering , Geoengineering, Foundations, Hydraulics , Solid Mechanics , Geotechnical Engineering & Applied Earth Sciences , Soil Science & Conservation , Soft and Granular Matter, Complex Fluids and Microfluidics
Study on the influence of magnesium/calcium ratios on bio-cemented sandy soils
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