Engineering and environmental properties of foamed recycled glass as a lightweight engineering material

Lightweight fill materials, including foamed aggregates are increasingly being used in civil engineering and infrastructure applications. This research assessed the engineering properties of foamed recycled glass through a laboratory evaluation to ascertain this novel recycled material as a lightweight fill material in civil engineering applications. The engineering assessment included particle size distribution, particle density, water absorption, minimum and maximum dry densities with a vibrating table, California Bearing Ratio (CBR) and Los Angeles (LA) abrasion tests. Shear strength properties of the recycled foamed glass were studied through large-scale direct shear tests. This recycled foamed glass is classified as a gap graded material. Due to high porosity, the coarse particles of this material have high water absorption of 60% and low particle density of 4.54 kN/m3, which is much lower than that of water. The minimum and maximum dry densities of this material are very low of 1.67 and 2.84 kN/m3, respectively. The LA abrasion of foamed recycled glass is lower than the requirement for pavement base/subbase material, being of 94%. The shear resistance at small shear displacement is thus low as shown by low CBR value of 9-12%. However, the shear resistance at large shear displacement is high as shown by high cohesion and friction angle of 23.36 kPa and 54.7°, respectively. The environmental assessment included pH value, organic content, total and leachate concentration of the material for a range of contaminant constituents. All the hazardous concentrations in the leachate are far lower than 100 times of those of the drinking water standards, indicating the foamed recycled glass as a non-hazardous material. The energy savings assessment demonstrates that the use of foamed recycled glass as engineering material has much lower energy consumption relative to a conventional aggregate-cement material in construction projects. The lightweight properties of the foamed recycled glass coupled with its satisfactory engineering and environmental results, particularly its high friction angle, indicates that the material is ideal for usage as a lightweight construction material in engineering applications such as non-structural fills in embankments, retaining wall backfill and pipe bedding.