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<p>Bio-cementation of sand with microbial-induced calcite precipitation (MICP) technique is one of the promising sustainable ground improvement solutions. In this study, stress–strain behaviour of MICP-treated standard Ennore sand of India was investigated for monotonically increased loading under unconsolidated undrained (UU) triaxial testing. The study was carried out with two ureolytic bacteria viz. <i>Sporosarcina pasteurii</i> and <i>Bacillus subtilis</i> considering 14&#xa0;days of treatment with 1.0 PV cementation solution for 12&#xa0;h interval. Tests were carried out for 40% relative density of sand with confining pressure values of 50, 75 and 100&#xa0;kPa. For the weathering effect, samples with three different wetting–drying (W-D) cycles (5, 10 and 15) were considered. It was observed that the mass loss for samples treated with <i>S. pasteurii</i> is lesser than <i>B. subtilis</i> considering W-D cycles. Further, calcite precipitate was determined to be significantly higher for samples with <i>S. pasteurii</i> treatment. For 15 W-D cycles, the reduction of calcite is from 30% (without W-D cycles) to 9.95% for <i>S. pasteurii</i> whereas it is from 25% to 4.7% for <i>B. subtilis</i>. The monotonic strength of treated samples without W-D cycles is found to be more than 3.0 times the strength of the untreated sand for both the bacterial strains for most of the cases. However, the degradation of strength for W-D cycles is more prominent for treatment with <i>B. subtilis</i>. The study indicates that the improvement for treatment with <i>B. subtilis</i> may be ignored for W-D cycles more than 15 for confining pressure less than 75&#xa0;kPa.</p>

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Experimental Study on Monotonic Behaviour of MICP-Treated Sand Using Different Ureolytic Bacteria Considering Wetting–Drying Cycles

  • 期刊论文

  • 发表日期：

    2025年6月11日

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  • Nilanjana Banik,
  • Rajib Sarkar

摘要

Bio-cementation of sand with microbial-induced calcite precipitation (MICP) technique is one of the promising sustainable ground improvement solutions. In this study, stress–strain behaviour of MICP-treated standard Ennore sand of India was investigated for monotonically increased loading under unconsolidated undrained (UU) triaxial testing. The study was carried out with two ureolytic bacteria viz. Sporosarcina pasteurii and Bacillus subtilis considering 14 days of treatment with 1.0 PV cementation solution for 12 h interval. Tests were carried out for 40% relative density of sand with confining pressure values of 50, 75 and 100 kPa. For the weathering effect, samples with three different wetting–drying (W-D) cycles (5, 10 and 15) were considered. It was observed that the mass loss for samples treated with S. pasteurii is lesser than B. subtilis considering W-D cycles. Further, calcite precipitate was determined to be significantly higher for samples with S. pasteurii treatment. For 15 W-D cycles, the reduction of calcite is from 30% (without W-D cycles) to 9.95% for S. pasteurii whereas it is from 25% to 4.7% for B. subtilis. The monotonic strength of treated samples without W-D cycles is found to be more than 3.0 times the strength of the untreated sand for both the bacterial strains for most of the cases. However, the degradation of strength for W-D cycles is more prominent for treatment with B. subtilis. The study indicates that the improvement for treatment with B. subtilis may be ignored for W-D cycles more than 15 for confining pressure less than 75 kPa.