Effect of Waste Glass Powder Particle Size on Flow and Compressive Strength of Slag-Based Alkali-Activated Materials

https://doi.org/10.5281/zenodo.20340560

Abstract

This study investigates the effect of waste glass powder particle size on the flow and compressive strength of slag-based alkali-activated mortar. Ground granulated blast-furnace slag was partially replaced with waste glass powder at 10%, 20%, and 30% by mass. Three waste glass powder particle-size ranges were considered: <75 µm, 75–150 µm, and 150–300 µm. A control mixture containing 100% slag was also prepared. All mixes were activated using 12 M sodium hydroxide and sodium silicate solution, with a sodium silicate-to-sodium hydroxide ratio of 0.6 and a binder-to-alkaline activator ratio of 2.5. The fresh properties were evaluated using a flow table test, while compressive strength was experimental at 7 and 28 days using three specimens per mix. The experimental results indicate that finer waste glass powder reduced flow because of its higher surface area, while coarser waste glass powder improved flow but reduced compressive strength. The highest experimental 28-day compressive strength was obtained by the mix containing 80% slag and 20% waste glass powder below 75 µm, reaching 72.0 MPa, which was 10.8% higher than the 100% slag control. Overall, the results suggest that moderate replacement of slag with fine waste glass powder can improve strength, but excessive replacement or coarser particle size may reduce mechanical performance.