The Efficiency of the Benefits of Tire-Derived Aggregate Backfill for Buried Concrete Pipes Beneath Paved and Unpaved Roads

Tire-derived aggregate (TDA) has been proposed in recent studies to be considered as part of backfill soil to reduce stress and strain developed in buried pipes. However, little attention is paid to checking the influence of TDA on the behavior of concrete pipes buried under trafficked roads. This research studies this topic using a verified numerical model that considers the three-dimensional nature of traffic load effects. Different road sections were considered in the analyses to cover the effect of the presence of the pavement layer and the effect of the thickness of the base and subbase materials. The results revealed that the presence of TDA decreases the bending moment induced in the pipe wall. However, the TDA performance was found to be remarkably influenced by burial depth, and it increases as the burial depth decreases. Furthermore, the TDA influence for pipes with outer diameters of 1.49 m and 2.89 m is much lower than that of 0.41 m and 0.79 m. Importantly, it was found that the highest reduction in the bending moment was achieved for the 1.0 m burial depth. The results of this research provide insight into the performance of TDA and, thus, will help practitioners make a decision regarding the use of TDA in the routine design of buried concrete pipes.