Effects of wollastonite powder on the geotechnical properties of a dispersive clayey soil

One of the most critical issues for civil engineers is the presence of dispersive clay in geotechnical projects. Furthermore, treating problematic soils with mineral materials has recently been proven to be a practical option from economic and environmental points of view. In this research, the behavior of wollastonite powder composed of calcium silicate (CaOSiO3) as an environmentally friendly stabilizer, was investigated concerning the engineering properties of a dispersive clay soil. At the beginning, the physical and chemical properties of the soil sample were determined and subsequently, several physical and mechanical tests were performed on the samples of clay modified by the additives with different curing periods. The results demonstrate that as the additive content increased to 10%, the liquid limit, plasticity index, and swelling percentage decreased by 9.6%, 41.4%, and 43.72%, respectively. The UCS and CBR values of wollastonite-treated soils grew up by 314% and 241%, respectively. Research has uncovered that when the wollastonite content mixes up to 8%, the friction angle and cohesion are in their highest value, and the final void ratio is the lowest. SEM analysis of treated soils show that during this process, the dispersive structure of the soil changes to a more flocculated structure, which considerably improves the clay dispersive qualities. As the final result, it can be mentioned that wollastonite powder can be considered as an effective additive for treatment of dispersive soil because of boosting stability, reducing costs, and improving strength and properties of such materials. Increasing wollastonite content in dispersive soil improves stability, dry density and strength, making it an effective additive for construction.As an optimal dosage, utilization of 8% wollastonite leads in minimizing soil dispersion and swelling.Mixing wollastonite with clayey soil results in significant increase of friction angle, cohesion, and maximum shear strength.