In this experimental study, comprehensive laboratory tests were conducted to investigate the mechanical properties of tire-derived aggregate (TDA) Type A and TDA-soil mixtures applicable in the construction of drainage layer, embankment fill, and backfill materials for retaining walls, pipes, and bridge abutments. This study was an investigation of the mechanical properties of TDA, as a lightweight material, and TDA-fine-grained soil mixtures for different mix ratios of 15%, 20%, 35%, 40%, 50%, and 60% of TDA-A relative to the dry weight of the soil. Various composite samples were tested using triaxial and direct shear apparatus. Measured properties include specific gravity, Proctor maximum dry density and optimal water content, unconfined compressive strength, peak compressive strength, shear strength, and hydraulic conductivity. Test results revealed that the addition of TDA to the soil significantly improved the compressive strength under confinement and permeability of the composite specimens. Based on the test results and supporting data from intensive literature reviews, the TDA-soil mixture showed very encouraging results for use in civil engineering applications as a lightweight backfill material.

This study evaluates the vertical stress transmission through a sand-tire mixture layer under impact, focusing on this innovative blended material that can impact underground structures such as tunnels or pipelines. By conducting consolidated undrained triaxial tests, the friction angle (phi) of the sand-tire mixture was determined, ranging from 29 degrees for pure tire to 41 degrees for pure sand. The vertical stress factor (alpha), representing the ratio of response load to applied load, was found to decrease significantly with increased tire content, with a reduction of up to 50% for mixtures containing 20% tire. Additionally, the vertical stress response decreased from 35 kPa for pure sand to as low as 15 kPa for mixtures with a high tire content under a consistent applied load of 65 kPa. This study not only presents a methodological advancement in analyzing sand-tire mixtures under dynamic loads but also suggests a sustainable approach to utilizing waste tire material in civil engineering projects, thereby contributing to environmental conservation and improved material performance in geotechnical applications.