Effect of waste glass powder particle size, content, and compaction pressure on the properties of autoclaved silicate brick

The present study evaluates the influence of waste glass powder particle size distribution, dosage, and compaction pressure on the performance of autoclaved silicate brick. Glass powder produced from container glass waste was incorporated into a quartz–lime mixture at 5, 10, and 15 wt.% in four fractions: ≤63, 63-140, 140-315, and 315-630 μm. The specimens were formed by semi-dry pressing and subjected to autoclave curing. Their average density, compressive strength, water absorption, thermal conductivity, and frost resistance were then determined. The results demonstrated that the modifying effect of glass powder strongly depends on its dispersity. The most favorable performance was obtained with the finest fraction (≤63 μm) at 10 wt.% and 10 MPa compaction pressure, where the average density reached 1860 kg/m3, compressive strength 14.5 MPa, water absorption 11.3%, and thermal conductivity 0.77 W/(m·°C). Coarser fractions showed a progressively weaker effect, and the 315–630 μm fraction was unfavorable relative to the reference composition. Frost resistance remained at F50 for all specimens. Increasing compaction pressure from 5 to 15 MPa enhanced densification and strength development while only slightly changing thermal conductivity. The results confirm the potential of finely ground waste glass as an effective modifying additive for silicate brick production.