Sustainable implementation of recycled tire-derived aggregate as a lightweight backfill for retaining walls

The study examined the use of recycled tire-derived aggregate (TDA) mixed with kaolin for retaining wall applications. The effects of the TDA content on the geotechnical properties of TDA-kaolin specimens such as the internal friction angle, maximum dry density (MDD), optimum moisture content (OMC) and saturated density (SD) were investigated. A total of 13 physical model tests were performed on a polymer concrete retaining wall using kaolin and TDA-kaolin mixtures as backfill material. Powdery, shredded, small-sized granular (1–4 mm) and large-sized granular (5–8 mm) TDA were mixed with kaolin at contents of 0%, 20%, 40%, and 60% by weight. The lateral wall displacement was measured on a fabricated steel strip footing close to the wall during loading. Lateral wall displacement also was simulated using finite element (FE) software (Optum G2). The results indicated that the addition of 60% TDA decreased the internal friction angle of the samples up to 8% compared to pure kaolin. In addition, the TDA particles caused the MDD of the TDA-kaolin samples to decrease up to 45%. The physical modeling results indicated that the kaolin samples mixed with 60% shredded TDA showed the highest elasticity in all tests at the failure moment of the footing