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Geomechanics and Engineering
  Volume 29, Number 1, April10 2022 , pages 79-90

Biocementation via soybean-urease induced carbonate precipitation using carbide slag powder derived soluble calcium
Yongshuai Qi, Yufeng Gao, Hao Meng, Jia He and Yang Liu

    Soybean-urease induced carbonate precipitation (EICP), as an alternative to microbially induced carbonate precipitation (MICP), was employed for soil improvement. Meanwhile, soluble calcium produced from industrial waste carbide slag powder (CSP) via the acid dissolution method was used for the EICP process. The ratio of CSP to the acetic acid solution was optimized to obtain a desirable calcium concentration with an appropriate pH. The calcium solution was then used for the sand columns test, and the engineering properties of the EICP-treated sand, including unconfined compressive strength, permeability, and calcium carbonate content, were evaluated. Results showed that the properties of the biocemented sand using the CSP derived calcium solution were comparable to those using the reagent grade CaCl2. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that spherical vaterite crystals were mainly formed when the CSP-derived calcium solution was used. In contrast, spherical calcite crystals were primarily formed as the reagent grade CaCl2 was used. This study highlighted that it was effective and sustainable to use soluble calcium produced from CSP for the EICP process.
Key Words
    biocementation; carbide slag powder (CSP); soil improvement; soybean crude urease extract; soybeanurease induced carbonate precipitation (EICP)
Yongshuai Qi, Yufeng Gao, Hao Meng, Jia He and Yang Liu: Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering, Hohai University,
Nanjing 210098, China

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