Value-Added Use of Milled Mixed-Color Waste Glass As a Supplementary Cementitious Material in Environmentally Friendly and Energy-Efficient Concrete Building Construction

Production of cement (the binder in concrete) is a highly polluting and energy-intensive process, accounting for about 6% of global, anthropogenic C02 emissions and close to 2% of worldwide primary energy use. This project focuses on partial (~20%) replacement of cement in concrete with milled (mixed-color) waste glass to improve the moisture barrier qualities, durability, dimensional stability and other engineering properties of concrete. These beneficial effects would be realized as far as waste glass is milled to micro-scale particle size for accelerating its chemical reactions with cement hydrates. The landfill-bound quantities of glass are adequate to significantly impact the concrete construction practice. Waste glass is generated largely in urban areas, where the bulk of concrete production also takes place. Broad use of milled waste glass in concrete would yield significant environmental, energy, and cost benefits, and also would enable more extensive use of recycled aggregate concrete. The Phase I effort identified desired particle size and dosage of milled (mixed-color) waste glass for beneficial use as partial replacement for cement in concrete. The favorable effects of milled waste glass on the chemical composition, microstructure, and key engineering properties (including stability under potential alkali-silica reactions) of normal and recycled aggregate concrete were identified through laboratory investigations. Theoretical and numerical studies were conducted to rationalize the experimental observations and to assess practical implications of using recycled glass concrete. A successful field study also was implemented in collaboration with concrete and recycling industries. The environmental, energy and (initial and life-cycle cost) benefits associated with partial replacement of cement with milled waste glass were quantified using the outcomes of Phase I effort. The proposed Phase II project will: (i) expand the experimental database on recycled glass concrete to cover broader ranges of concrete materials and engineering properties; (ii) corroborate the statistical significance of the benefits rendered by milled waste glass and verify the statistical control over production of recycled glass concrete; (iii) identify the mechanisms through which milled waste glass benefits the engineering properties of normal and recycled aggregate concrete; (iv) thoroughly assess the gains in service life and life-cycle economy of major concrete-based infrastructure associated with the use of milled waste glass; (v) implement and monitor large-scale field projects to demonstrate the scalability, compatibility with prevalent construction practices, and practical value of recycled glass concrete; and (vi) evaluate the environmental, energy, and cost benefits of recycled glass concrete in different applications and service environments.