Evaluation of One-Part Slag–Fly-Ash Alkali-Activated Mortars Incorporating Waste Glass Powder

Abstract

This paper describes an experimental investigation into the properties of ambient cured one-part alkali-activated materials (AAMs). Mixes incorporating waste glass (WG), ground granulated blast-furnace slag (GGBS), fly ash (FA), and sodium metasilicate pentahydrate were assessed in terms of workability, water absorption, physical and mechanical properties, and environmental impact. Microstructure investigations on selected mixes were also carried out. The GGBS-only mixes had low workability and high early strength that declined over time, whereas FA-only mixes had virtually no strength. Equal proportions of WG and GGBS provided similar fresh properties to those of GGBS mixes yet comparatively higher strengths and a positive strength time gradient. Mixes incorporating 50% GGBS, 25% FA, and 25% WG had the best balance between mechanical properties and workability, with compressive strengths above 40 MPa suitable for structural applications. An increase in activator content from 14% to 21% enhanced the strengths by 39.1%–54.6%. The flexural strengths were largely proportional to the compressive strengths, the water absorption properties were like those of cement mortars, and dry densities depended on the proportions of the constituent binders. Finally, the AAM mixes had between 53% and 72% less embodied carbon compared with a corresponding cement mortar.