Stabilisation of organic soils with alkali-activated binders

Peat and organic soils are soft soils with high compressibility and low mechanical strength. Therefore, construction over organic subgrades leads to the road foundation suffering unacceptable settlements. Besides, traditional binders such as Portland cement and lime could not effectively enhance the mechanical properties of the organic soils. Consequently, in most cases, these soils are replaced by high-quality materials. This study investigates the effectiveness of using alkali-activated binders to stabilise organic soils. Industrial by-products such as ground granulated blast furnace slag (GGBFS) and fly ash (FA) were used and activated by 10 M sodium hydroxide and sodium silicate solutions to prepare geopolymer binders. The cured specimens were characterised using compression strength tests, one-dimensional consolidation tests, scanning electron microscopy, and energy-dispersive X-ray spectroscopy tests. The experimental results indicated that utilising alkali-activated binders to stabilise the organic soils successfully improved mechanical strength and decreased settlement. The optimum alkali-activated binders resulting from this study can modify the peat soil consisting of 75.32% organic matter to be employed as the road subgrade material.