Strength and Microstructural Developments in Magnesia-GGBS Stabilised Biochar-Sequestered Acid Sulphate Soil

This study assessed the effectiveness of magnesia (MgO) and ground granulated blast-furnace slag (GGBS) in improving the strength of acid sulphate soil (ASS) and the feasibility of sequestering biochar carbon in stabilised ASS. To fulfil the objective of this study, ASS was treated with reactive MgO at 5 to 15%, GGBS at 10 to 20% and biochar at 10%. A range of testings, including pH, uniaxial compressive strength (UCS) test, scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis, was carried out to investigate strength and microstructural development of the treated ASS over a 180-day curing period. The results of this study showed that MgO-activated GGBS could effectively improve the strength of ASS with an optimum MgO to GGBS ratio of 1:4. Inclusion of biochar can lead to a slight reduction of approximately 10% in strength development of the MgO-GGBS treated ASS. The reduction is due to the porous structure of biochar.