Mechanical and Microstructural Behavior of Sand Treated by Filamentous Fungus Mycelium Mediated Calcite Precipitation

Abstract

Fungus Mycelium mediated Calcite Precipitation (FMCP) is a novel bio-inspired method for enhancing the mechanical and microstructural properties of sand. This study investigates the potential of Aspergillus Niger fungus mycelium to induce calcite precipitation in sand, thereby improving its unconfined compressive strength (UCS) and permeability. The experimental approach involves mixing sand with Aspergillus Niger and subsequently injecting a cementation solution containing urea and (Formula presented.) in an equimolar 1:1 ratio at 24-hour intervals. The effect of different treatment durations (7, 14, 21, and 28 days) on the UCS of the samples is examined. Our findings demonstrate that the highest average UCS of 3.93 MPa was achieved after 28 days using FMCP, corresponding to an average calcium carbonate content of 15.19%. Additionally, permeability of FMCP treated sand decreased to 99.54% compared to untreated sand. The Scanning electron microscopy identified the presence of fungus mycelia and calcium carbonate crystals that bind the sand grains together resembling fibrous structure. The Energy-Dispersive X-ray Spectroscopy analysis confirmed the presence of calcium carbonate crystals associated with the sand grains and fungal mycelium. These findings contribute valuable insights into the feasibility of FMCP as a sustainable approach to soil improvement, with implications for geotechnical and construction applications.