Recycled Asphalt Shingles Mixed with Granular Byproducts as Structural Fills

In this study, recycled asphalt shingles (RAS) were evaluated for potential use as structural fill in highway embankments or backfills behind retaining walls. Bottom ash (BA) and foundry slag (FS) were also investigated as additives to RAS to enhance its mechanical properties. The engineering properties of RAS:BA/FS mixtures including compaction characteristics, hydraulic conductivity, compressibility, shear strength, and the coefficient of lateral earth pressure at rest were evaluated in a systematic manner. The results show that the addition of bottom ash and foundry slag significantly reduces the compressibility of RAS while increasing the drainage capacity and shear strength. The RAS:BA/FS mixtures are a favorable light weight material for use as embankment fills or backfill behind retaining walls.