Effect of waste-based geopolymers on mechanical and geotechnical properties of expansive soil

Abstract. Geopolymers are cementitious materials that are known for their eco-friendly properties. They have the unique ability to harden quickly, exhibit impressive strength, and show minimal shrinkage. Additionally, they have excellent resistance to both acidic and alkaline corrosion. The impressive qualities of this product offer long-lasting benefits in enhancing the strength, stability, and durability of the subgrade soils. The current study aims to investigate the use of Olive Waste Ash - Geopolymer (OWA-GP) as a sustainable and environmentally friendly substitute for cement in soil stabilization using unconfined compressive strength (UCS). To evaluate the geopolymer's UCS, various combinations of these materials were tested, along with alkalis (NaOH and Na2SiO3) in ratios (SS/SH; 1:2, 1:1, 3:2, 2:1), concentrations (5M, 10M, and 15M), and source material content (10%, 20%, and 30%) by weight of soil, with curing periods of 1, 7, and 28 days. OWA-GP (10M 3:2, 20%) achieved a maximum strength of 2.99 MPa after 28 days of curing. Geopolymers have been shown to outperform cement-stabilized soil and soil stabilized with cement. This demonstrates geopolymers' superiority over cement and the possibility of expanding their use as a sustainable method of soil and ground improvement.