Recycled Sands from Demolition Wastes as a Natural Sand Substitute Material in Pavement Construction

The accumulation of construction and demolition (C&D) waste in landfills is deemed a worldwide concern which is exacerbated by the impact of rapid urbanization and increased construction activities. The massive amount of waste disposal and increased demand for non-renewable virgin quarry materials such as natural sand triggers the urgent need to adopt various kinds of recycled materials in geotechnical fields, such as washed recycled sand (RS). Washed RS reviewed in this study is derived from C&D waste at a local washing plant in Melbourne, Victoria. Two types of washed RS were used as the target materials in this research based on their ranges of particle size: coarse recycled sand (CRS) and fine recycled sand (FRS). CRS and FRS have precisely the same source materials, while FRS experiences an extra round of the washing process. Extensive geotechnical laboratory tests were performed on an unbound stage, and the results indicated that both CRS and FRS exhibited similar geotechnical behavior with natural sand when used as pavement subgrade materials. Further, the geoenvironmental test suggested that the application of washed RS would not adversely impact the surrounding environment or human health. In addition, RS stabilized with 4% Portland Cement was found to effectively fulfill the relative requirement regulated by the local road authority through the unconfined compressive strength (UCS) test. This study highlighted that CRS and FRS could successfully substitute the role of natural sand required for pavement construction.