Influence of Curing Stress on Bio cemented Sand: Shear Modulus Degradation and Design of Treatment Molds

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4. Influence of Curing Stress on Bio cemented Sand: Shear Modulus Degradation and Design of Treatment Molds

Climate change is intensifying geohazards globally, with rising sea levels and extreme weather events increasing the frequency and severity of ground failures such as soil liquefaction, landslides, and excessive settlement. These phenomena pose significant threats to infrastructure stability, particularly in coastal and mountainous regions. As traditional ground improvement techniques often rely on environmentally harmful materials and processes, there is an urgent need for sustainable alternatives that can enhance soil properties while minimizing ecological impact. Biocementation, specifically Enzyme-Induced Carbonate Precipitation (EICP), has emerged as a promising, readily applicable eco-friendly solution. However, the influence of in-situ stress conditions on the effectiveness of this technique remains poorly understood, potentially limiting its practical application. This study hypothesizes that the curing stress, defined as the constant confining pressure applied during calcium carbonate precipitation, significantly affects the dynamic properties of EICP-treated sands. To test this hypothesis, we developed novel treatment molds compatible with resonant column devices, enabling in-situ EICP treatment and immediate dynamic testing without sample disturbance. This innovative approach allows for a more accurate representation of field conditions compared to traditional laboratory methods. Using these custom-designed molds, we conducted a series of resonant column tests on sand specimens treated under varying curing stresses (0 and 50 kPa). We evaluated the shear modulus degradation curves to quantify the impact of curing stress on the dynamic behavior of biocemented sands. Our results demonstrate that specimens treated under 50 kPa curing stress exhibited markedly higher maximum shear modulus and distinct degradation patterns compared to those treated without confinement. These findings not only validate the importance of considering curing stress in biocementation processes but also highlight the potential for optimizing treatment protocols to enhance soil improvement outcomes. 

2025 International Conference on Bio-mediated and Bio-inspired Geotechnics (ICBBG2025)

General session: Fundamental research on biogeotechnics