The Application of MICP for Strengthening of Mine Tailings and Peats
Abstract
Peat and mine tailings present significant challenges in geotechnical engineering due to their adverse mechanical properties. Peat, rich in organic materials, demonstrates considerable compressibility and permeability, leading to significant settlements during construction. Consequently, building on peat is fraught with risks because of its low bearing capacity, with non-uniform settlements posing a threat to structural integrity. Mine tailings, remnants of mining activities, frequently contain harmful elements. It is imperative to store them within tailings dams' saturated layers, isolating them from the environment and averting potential contamination. However, when stored, these tailings can undergo liquefaction in response to both monotonic and cyclic loads. Given these challenges and the increasing scrutiny on traditional treatments like Portland cement for environmental reasons, an alternative solution becomes imperative. This study advocates for Microbially-Induced Calcite Precipitation (MICP) as a viable technique to enhance peat and mine tailings' mechanical properties. In this research, these materials are subjected to treatments and subsequent Direct Simple Shear (DSS) testing under different loading conditions, drained and undrained under monotonic and cyclic loads. The results were used to evaluate parameters such as density, yield and residual strength, brittleness, state parameter, stiffness, compressibility, liquefaction resistance, and dynamic characteristics. The outcomes highlighted pronounced improvements in these parameters upon successful MICP application. Additionally, X-ray diffraction (XRD), scanning electron microscopy (SEM) images, and energy-dispersive X-ray spectroscopy (EDS) are employed to scrutinize the microstructural and compositional transformations in the materials post-MICP treatment.