Freeze-thaw durability and environmental risk assessment of silty soil improved using EICP combined with magnesite tailings powder
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View abstract on PubMed
Summary
This summary is machine-generated.Enzyme-induced carbonate precipitation with magnesite mine tailings improves silt stability against freeze-thaw cycles. This novel treatment enhances soil strength and reduces environmental risks for foundations in cold regions.
Area Of Science
- Geotechnical Engineering
- Environmental Science
- Material Science
Background
- Enzyme-induced carbonate precipitation (EICP) is promising for soil improvement, but long-term stability, especially under freeze-thaw (FT) cycles, remains understudied.
- Foundation soils in seasonally frozen regions face deterioration due to repeated FT cycles, impacting infrastructure.
- Existing research on EICP-treated soils largely overlooks durability and performance in challenging environments.
Purpose Of The Study
- To investigate the efficacy of combining EICP with magnesite mine tailings (MMT) for enhancing silt stability in seasonally frozen regions.
- To evaluate the impact of repeated freeze-thaw cycles on the mechanical properties, physical characteristics, and microstructure of EICP-MMT treated silt.
- To assess the environmental risks associated with heavy metal leaching from the treated soil.
Main Methods
- Silt samples were treated using enzyme-induced carbonate precipitation (EICP) combined with magnesite mine tailings (MMT).
- Treated and untreated silt samples were subjected to multiple freeze-thaw (FT) cycles with varying temperature ranges.
- Mechanical properties (unconfined compressive strength, secant modulus), physical characteristics (apparent porosity, permeability), microstructure, and heavy metal leaching were evaluated.
Main Results
- Prior to FT exposure, EICP-MMT treatment significantly increased unconfined compressive strength (1.67x) and secant modulus (3x), while decreasing apparent porosity (20%) and permeability (93%) compared to untreated silt.
- Following FT cycles, EICP-MMT treated silt exhibited superior strength, toughness, and stiffness with lower apparent porosity than untreated silt, though improvements decreased with more cycles.
- The treatment substantially reduced heavy metal leaching and bioavailability, indicating lower environmental pollution risks.
Conclusions
- EICP-MMT treatment offers a viable strategy for improving the durability and mechanical performance of silt subjected to freeze-thaw cycles.
- The combined treatment enhances soil stability and reduces environmental risks, making it suitable for foundational applications in seasonal permafrost regions.
- Further research could optimize treatment parameters to further mitigate the diminishing improvements observed with an increasing number of freeze-thaw cycles.
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