Select Engineering Characteristics of Crushed Glass

Select engineering characteristics of crushed glass produced using two processing techniques (crushing versus screening) to an American Society of State Highway and Transportation Officials No. 10 gradation were experimentally evaluated. The crushed glass samples were classified as well graded sands with gravel (SW) and exhibited excellent strength and workability characteristics. The low specific gravity (2.49) contributed to crushed glass having compacted maximum dry densities on the order of 16.6–16.8 and 17.5–18.3 kN/m^3 by the standard and modified Proctor compaction tests, respectively. Direct shear friction angles were measured between 47 and 62° at normal stresses ranging from 0 to 200 kPa. Friction angles obtained by drained triaxial shear were on the order of 48° for similar stress ranges. Measured hydraulic conductivities were on the order of 1–6×10^–4 cm/s. The results indicate that crushed glass is a readily available, freely draining, environmentally clean, relatively low cost material whose engineering performance properties generally equal or exceed those of most natural aggregates. Despite these favorable characteristics, there are many real and perceived barriers to increasing the beneficial use of crushed glass, and key examples are provided in an effort to illustrate these unnecessary barriers.