FIELD INVESTIGATION OF CONCRETE INCORPORATING MILLED WASTE GLASS

About 12.5 million tons of waste glass is generated annually in the U.S., 77% of which is disposed of in landfills. Waste glass can be cost-effectively collected in mixed colors, but has limited markets. Mixed-color waste glass offers desired chemical composition and reactivity for use as a supplementary cementitious material for enhancing the chemical stability, moisture resistance and durability of concrete. To realize this potential, waste glass needs to be milled to micro-scale particle size for accelerating its beneficial chemical reactions in concrete. In this investigation, recycled glass concrete was produced by partial replacement of cement with milled waste glass. Recycled glass concretes with 15, 20 and 23 wt.% of cement replaced with milled glass were investigated in field (pavement) construction projects. The compatibility of recycled glass concrete with conventional construction techniques was evaluated, and the field performance of recycled glass concrete under weathering effects (in mid-Michigan) was monitored over a two-year period. Compressive strength, water sorption, chloride permeability, and abrasion resistance tests of recycled glass concretes were performed on cores drilled from the experimental pavements, and the results were compared with those obtained with normal concrete. Flexural strength tests were carried out on concrete specimens at various ages. Test results indicated that recycled glass concrete incorporating milled waste glass as partial replacement for cement offers excellent strength and durability attributes when compared with normal concrete. The pozzolanic reactions of milled waste glass with cement hydrates improve the microstructure and chemical composition of concrete. Use of milled waste glass in concrete as partial replacement of cement represents an important step towards development of sustainable (environmentally friendly, energy-efficient and economical) concrete-based infrastructure systems.