Biochar Sequestration in Lime-Slag Treated Synthetic Soils: A Green Approach to Ground Improvement

Unconfined compressive strength (UCS) of synthetic biochar mixed clays (BMC) treated with lime-GGBS has been investigated. Biochar utilized in this study was produced from the slow pyrolysis of green waste residue. Treated biochar mixed clays have also been tested for microstructural and mineralogical developments. Results of this study showed that a lime content of 2wt%, which is much lower than the conventionally used 10wt% lime for synthetic clay, can be effectively incorporated to improve BMCs. X-ray Diffraction analysis carried out on treated BMCs showed the development of cementitious minerals (CSH, ettringite). Scanning Electron Microscopy with Energy Dispersive Spectrum (EDS) enabled identification of three separate types of microstructural interactions between biochar and soil particles, namely interface cementation, surface deposition and pore space filling by cementitious minerals, all of which are responsible for the enhancement of UCS with curing.