Stabilization of Soil using Flyash and Granulated Blast Furnace Slag: A Review

In India about 160 million tons of flyash is produced mainly produced in coal-fired electric and steam generating plants, of which only 100million tons are used annually. The rest of which is used as fills in dumps, while grounded granulated blast furnace slag (GGBS) is a solid waste generated by iron and steel plants in about 40 million tons annually and in future, recycling will inevitably become an important measure for the environmental protection and therefore will be of great social and economic significance. Flyash is rich in silica and alumina while has less than 20% lime (CaO) which is well complemented by GGBS with 40-50% lime. Lime needs to be added in very small quantity as a chemical activator (cementing agent) to create a basic environment and produce cementitious compound. The expansive nature of Black Cotton soil is very poor and undependable as a subgrade material. The joint use of these two materials to form a binder provides new opportunities to enhance pozzolanic activities that may reduce the swell potential and increase the unconfined compressive strength of expansive clays. Hence the main objective is to treat and stabilize the soil such that undesirable characteristics are modified by a suitable stabilization material and technique.