An Innovative Investigation of Effects of Natural Zeolite on Microstructure and Physicomechanical Characteristics of Clayey Soil Under Different Curing Conditions

Geotechnical engineers are exploring the potential benefits of incorporating mineral additives like zeolite into soil stabilization, which is critical in construction activities. This laboratory experiment aims to assess the impact of zeolite on the microstructural and mechanical characteristics of clayey soil under both standard and temperature curing conditions. The study involves blending fine-grained clayey soil with different proportions of natural zeolite (0, 5, 10, 15, 20 percent by weight compared to the dry weight of the soil) to test the unconfined compressive strength (UCS), direct shear test (DST), and ultrasonic pulse velocity (UPV) under standard curing conditions (7, 28 and 90 days) at laboratory temperature and different curing temperatures (3 days at temperatures of 20°C, 40°C and 60°C). The microstructure of the specimens was also examined using a scanning electron microscope (SEM). Results from the study show that incorporating 5% zeolite into clayey soil enhances shear strength parameters and increases UCS significantly, 1.85 and 2.4 times higher than that of clayey soil, under both standard 90-day curing and accelerated curing at 60°C, respectively. Also, due to the improvement of shear strength parameters due to the addition of zeolite in two conditions of standard 90-day curing and accelerated curing at 60°C, the growth of 1.55, 1.86, 1.53, and 1.72 times has been observed for cohesion and internal friction angle of the soil, respectively. Analysis of the microstructure of the specimens revealed better compaction and improved particle connection due to the formation of aluminosilicate hydrate (ASH) gel with the addition of zeolite to the soil, illustrating the positive impact on mechanical characteristics.