Tire Derived Aggregates As a Sustainable Recycled Material for Retaining Wall Backfills

Tire derived aggregates (TDA) offer potential environmental, technical, and economical benefits for retaining wall applications. For example, when compared to natural soils, TDA materials offer the advantage of reduced lateral pressures and settlement due to smaller unit weight, and potentially higher drainage capacity. This paper presents a technical and economical assessment of TDA materials for retaining wall backfills. The technical assessment includes results on model retaining wall tests and also from centrifuge tests to assess the lateral pressures generated by TDA materials. The lateral pressures are compared to tests using conventional mineral soil backfills. The test results show TDA backfills generate lower lateral pressures for at-rest conditions and for active conditions. The lower lateral pressures, coupled with lower unit weights translate into substantially lower retaining wall costs due to savings from smaller wall and footing dimensions, and less steel reinforcement quantities associated with the lower loading demand.