Comparative effects of olivine and sand on KOH-treated clayey soil

Abstract Improving the strength of clayey soils remains a key concern in geotechnical practice. This study presents a comparative investigation of the effects of olivine waste and sand grains on a clayey soil, both in the absence and presence of potassium hydroxide (KOH). The samples were tested under undrained conditions with varying curing periods and different confining pressures. Samples treated with sand or olivine showed increased strength, with sand outperforming olivine due to its higher volume. In the presence of KOH, the strength increased in both cases, with sand-treated samples showing higher values than those treated with olivine. Under a confining pressure of 100 kPa and a curing period of 90 days, strength increased by 399% with olivine and by 613% with sand. At 400 kPa confining pressure, these values reached 604% for olivine and 856% for sand. The highest cohesion (390 kPa) and internal friction angle (22.03°) were obtained in the sand added sample activated with KOH in 90 days, followed by the olivine added samples activated by KOH in 90 days with a cohesion value of 270 kPa and a friction angle of 20.56°. Mineralogical analyses were carried out to examine crystal formation resulting from the chemical reaction. The study presents extensive experimental data, highlighting the potential of olivine as an environmentally friendly material and a sustainable alternative for soil stabilization, with lower carbon emissions compared to conventional methods.