Select Engineering Characteristics of Crushed Glass

TLDR

Although crushed glass has favorable properties, many real and perceived barriers hinder its widespread use. This study selects engineering characteristics of crushed glass produced by crushing versus screening to meet AASHTO standards. Ten gradations of crushed glass were experimentally evaluated. The crushed glass was classified as well‑graded sand with gravel, exhibited excellent strength and workability, low specific gravity (2.49), compacted maximum dry densities of 16.6–16.8 and 17.5–18.3 kN/m³, shear friction angles of 47–62° (direct shear) and ~48° (drained triaxial), hydraulic conductivities of 1–6 × 10⁻⁴ cm/s, and overall performance equal to or better than most natural aggregates, making it a readily available, freely draining, environmentally clean, low‑cost material.

Abstract

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 17.5-18.3kN/m3 by the standard and modified Proctor compaction tests, respectively. Direct shear friction angles were measured between 47 and 62° at normal stresses ranging from 0to200kPa. 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 1-6×10-4cm/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.