Properties of chipped rubber roofing membrane and sand mixtures for civil engineering applications

• Density of shredded roof membrane-sand mixture from sieve analysis and compaction test.
• Permeability coefficient of new composite material from constant head permeability test.
• Shear strength parameters of new composite material from direct shear and triaxial tests.
• Volume change and compressibility of new composite material from laboratory test.
• Suggestions for potential application of the new material in civil engineering projects.

Waste rubber materials have been a popularly recycled material in Civil Engineering applications in recent years. The use of chipped rubber, particularly waste tires, has proven to have economical and performance benefits while making use of common waste materials. Within the construction and demolition sector, EPDM rubber roofing membranes are now being disposed of by chipping the waste sheets into uniform, angular chips roughly 1–2 mm in nominal diameter. The shredded roofing membrane is fire resistant and has potential to be used as a replacement for conventional materials in Civil Engineering projects. In this study, the geotechnical properties of chipped rubber roofing membrane are investigated both alone and mixed with a sand at various ratios by weight. To determine potential suitability as a lightweight material, Proctor Compaction Tests, Direct Shear Tests, Triaxial Tests, and Permeability tests were performed on EPDM rubber chip-sand mixtures in ratios by weight of 100%, 75%, 50%, and 25%. The results show that the new composite material is light weight but has high permeability and friction angle that are comparable to a granular soil. Based on these properties it is believed that the new material can be used as light weight retaining wall backfill, drainage layer in landfills, insulator in roadway subgrades and embankment fill.