Effect of Ground Glass Composition on the Compressive Strength, Replacement Level, Hardened Air-Void System, and Microstructure of Portland Cement Mortars

Abstract

Utilizing ground glass as a pozzolan in concrete could provide a high-value market for discarded glass, and help to reduce the amount of portland cement used, thereby reducing the CO2 emissions associated with the concrete mixture. 18 different waste glass sources from across the country were used to make mortars containing 20% and 30% portland cement replacement levels by mass. Compressive strength was measured through six months. The hardened air void structure was analyzed past six months. Most glasses met 75% Strength Activity Index at 7 and 28 days when a 20% replacement level was used. An increased replacement level of 30% resulted in lower compressive strength for all but E-glass. Glass composition was found to affect the compressive strength and hardened air void structure, though strength variation among glasses of the same type was found to be less than strength variation between different types of glass.