Implementation of geopolymer for stabilizing granular soil

River sand, despite being an available material, a low-cost, but loose sandy soil, cannot be used as a construction material in civil engineering works due to its poor grain size distribution and low bearing capacity. Geopolymer is recently considered a novel eco-friendly alternative to conventional soil enhancement and stabilization materials, such as ordinary Portland cement (OPC) and lime, which harm the environment in terms of high CO2 emissions and energy consumption. Hence, this study investigated the potential strengthening of loose sandy soil using geopolymer. Different alkaline activator (AA) solution ratios were used with varying curing temperatures for producing the river-sand geopolymer. The river sand-geopolymer specimens were matured in the oven at different temperatures for 48 hours. A series of unconfined compressive strength (UCS) tests were carried out on the 3, 7, 14, and 28 days of curing. The results show that the UCS of the river-sand geopolymer matrix significantly increased with increasing the main ingredient of its activator solution (sodium silicate) as well as the temperature. The UCS reached 13.42 MPa when the AA solution ratio was 0, whereas it decreased up to 1.15 MPa when the AA solution ratio became 1.5 at a temperature of 60 °C and 28 days of curing. Therefore, geopolymer is feasible and sustainable material to improve problematic soil for different applications.