Soft Clay Eco-Friendly Improvement by Ground Granulated Blast Furnace Slag and Quicklime

Due to increasing environmental problems, the reuse of waste materials has become essential, and ground-granulated blast furnace slag is one of these materials. This study investigated the effects of ground granulated blast furnace slag, lime, and sodium silicate as alternative additives on soft clay. Forty-five unconfined compressive strength tests were conducted using five different percentages of ground granulated blast furnace slag (2%, 4%, 6%, 8%, and 10% of the total dry weight), three different percentages of sodium silicate (1%, 1.5%, and 2.5% of the total dry weight), and a constant percentage of 6% lime (by total dry weight). The specimens were cured for 7, 28, and 90 days. Also, three consolidation tests were conducted on improved samples with optimal percentages of lime and ground granulated blast furnace slag and 1%, 1.5%, and 2.5% sodium silicate by total dry weight. The results showed that using a mixture of ground granulated blast furnace slag, lime, and sodium silicate improved the soil’s unconfined compressive strength, and this stabilizing effect increased over time. Furthermore, the settlement of the improved samples increased, and simultaneously, the void ratio decreased. Additionally, scanning electron microscopy and energy-dispersive X-ray analysis were performed on specimens. The results showed that the presence of additives increased the soil samples’ strength due to increased hydration reactions and porosity reduction.