Durability and cost analysis of a soil stabilized with alkali-activated wastes: fly ash and eggshell powder

Geopolymers with the inclusion of waste materials, viz., fly ash and slag, have been considered for various applications as a substitute for non-eco-friendly conventional binder, i.e., cement. Nevertheless, none of the studies have focused on soil stabilization using novel alkali-activated precursors—fly ash and calcium-rich eggshell powder with different curing temperatures. The objective of the present study is to analyze the effect of alkali-activated fly ash and eggshell powder on the durability of reference soft soil mix. The sodium silicate and sodium hydroxide solution were used to activate the precursors. The specimens, with varying percentages of precursors (10%, 20%, 30%, 40%, and 50%), were heated for 7 days at 25 °C, 50 °C, and 80 °C before subjecting to 12 wetting–drying cycles. The outcomes of the investigation show that the residual strength increases with the increase in geopolymer concentration following a similar pattern of 7-day compressive strength. A decrease in the weight loss of geopolymer-treated clay was detected for the specimens earlier cured at 50 °C. Further, the cost analysis suggested that the eggshell powder–fly ash geopolymer is a much cheaper binder than conventional cement concrete.