Effect of cyclic loading on the compressive strength of soil stabilized with bassanite–tire mixture

This study investigates the effect of static and cyclic loading on the performance of soil stabilized with recycled bassanite, produced from gypsum wastes, mixed with waste tire shreds. Recycled bassanite was mixed with furnace cement in different proportions to prevent the solubility of bassanite. Different percentages by weight of this admixture were mixed with the test soil. In addition, different percentages and sizes of waste tire shreds along with a fixed content of bassanite admixture were mixed with the tested soil. The static and cyclic strength and stiffness parameters of soil specimens treated using the different schemes were measured from cyclic triaxial tests. The results obtained showed that recycled bassanite improved the strength of the treated soil, but the increase in compressive strength was much higher compared to the tensile strength. The strength of the treated soil increased as the admixture content and proportion of cement in the admixture increased. Shredded waste tire improved the tensile strength of the treated soil, but slightly reduced its compressive strength. Cyclic loading resulted in significant degradation of strength for samples treated with bassanite admixture; however, incorporation of shredded tire reduced this degradation. It was also noted that the size of shredded tire had negligible effect on cyclic strength of the treated soil. The results also showed that the fatigue life of stabilized soil increased with the increase of shredded tire content and bassanite admixture. As expected, the number of load cycles had a negative effect on the strength of treated soil: as the number of load cycles increased the strength degradation increased for both treated and untreated soil samples. The effect of number of cycles was more pronounced in the case of unreinforced soil sample while it reduced when tire shreds were incorporated in soil mixture.