Engineering Properties of Recycled Materials for Use as Embankment Fill: Fid-Bau Portal

Engineering Properties of Recycled Materials for Use as Embankment Fill

Soleimanbeigi, A. / Edil, T. B. / Benson, C. H.

Use of recycled materials promotes sustainability in geotechnical construction. Compaction characteristics, hydraulic conductivity, shear strength, and compressibility of bottom ash (BA), foundry slag (FS), recycled asphalt pavement (RAP), and recycled asphalt shingles (RAS) that are produced in large quantities were characterized. Results showed that BA, FS, and RAS have lower maximum dry unit weight than compacted sand and the dry unit weights are not sensitive to compaction moisture content. Shear strength of the tested recycled materials are adequate to provide stability for typical highway embankments. The measured hydraulic conductivities provide sufficient drainage capacity for embankment fills. Results of one-dimensional compression tests showed that BA and FS have comparable compressibility to that of compacted sand up to vertical effective stress (σ'_v) of 200 kPa after which BA and FS exhibited higher compressibility than sand due to crushing of individual particles. Compressibility of RAS is significantly higher than that of sand, which makes the material unsuitable as embankment fill. RAP consistently has higher compressibility than sand; however, settlement of typical highway embankments constructed with RAP is still below the typical allowable limit. BA, FS, and RAP have appropriate engineering properties for use as structural fill in typical highway embankments. RAS should be mixed with at least 50% of granular additive to reduce compressibility to an acceptable limit. Construction of embankments with RAS mixture or RAP is recommended during warm seasons to induce thermal preloading and reduce compressibility.