EVALUATION OF SHEAR STRENGTH AND PARTICLE BREAKAGE OF CRUMB TIRE-CALCAREOUS SAND MIXTURE

One of the main problematic soils in nature with which we are dealing is carbonate or calcareous sand. Carbonate sediments are located in temperate and tropical areas and cover approximately 40% of the ocean surface. Theses soils are made up of the rest of the body of marine creatures, particularly tiny cowries or have physical or chemical origins.In Iran, Northern Shores of the Persian Gulf and islands of Qeshm and Hormoz contain Calcareous Sands. The most significant characteristic of this soil is particle breakage under shear stress that decreases the shear strength, which also affects its Stress-Strain behavior. On the other hand, due to the large increase of transportation in these regions, the accumulation of scrap tires leads to environmental problems. Therefore, in order to use these materials much better as they are, they can be reused in geotechnical engineering for providing geo-materials with better quality and helping to have a cleaner environment.In this study, the effect of adding Crumb Tire to the Calcareous Sands of Qeshm Island was evaluated. By doing several tests, effect of adding Crumb Tire on the shear strength of Calcareous Sand and its crushability was evaluated. In this regard, Consolidated-drained triaxial tests on the crumb tire-sand mixtures were conducted under the confining pressures of 100, 350, and 600 kPa using two different relative densities of 30% and 60%. By volume percentage of 0, 10, 15, 20 and 30%, Sand and sand-crumb tire mixtures were examined, and the optimum crumb tire content was found to be 10 percent for the considered type soil.Finally, the results showed that by adding 10% Crumb Tire to the Calcareous Sand, the internal-friction angle of loose specimens increased by approximately 8.9% compared to pure sand specimens. Furthermore, the particle breakage factor decreased by adding specific percentage of Crumb Tire to the soil. Hence, this issue could be considered as a noteworthy achievement because of Crumb Tire improving effects on the mechanical characteristics of a problematic soil in nature.