Fly Ash and GGBS Mixtures for Geotechnical and Geo-Environmental Applications

In this study, the joint activation of fly ash/ground granulated blast furnace slag (GGBS) mixtures has been evaluated in order to find its suitability in geotechnical and geo-environmental applications. Unconfined compressive strength (UCS) tests have been conducted on fly ash/GGBS mixtures prepared at their respective optimum moisture content (OMC) and maximum dry density (MDD) and cured for different periods. The mixture consisting of 70% fly ash and 30% GGBS developed better strength than either of the individual materials. Thereafter, 70:30 mix of fly ash and GGBS was selected for use as binder material for the stabilization of contaminated and expansive soils. With a view to stabilize contaminated soil, the adsorption characteristic of lead ions onto the mixture was determined through batch tests conducted at different pH and time intervals. It was found that the removal efficiency of the lead ions by the binder was comparatively high when compared to fly ash alone. The kinetic studies suggested that the reaction involving the adsorption of lead ions followed second-order kinetics. In the stabilization of expansive soil, the results demonstrated improvement in the plasticity characteristics of the expansive soil as well as reduction in the swell potential. Based on the results obtained in this present study, it can be concluded that combined use fly ash and GGBS can be advantageous when compared to using them individually.