Glass powder as partial replacement of sand in the production of concrete blocks

Glass waste is generated in large quantities worldwide, yet only a small portion is recycled or reused. To support the circular economy, it is essential to explore alternatives that incorporate this waste into new production chains, such as in civil construction. This study investigates the technical feasibility of replacing sand with glass powder in the production of dry concrete blocks. Four mixtures were tested, with sand replaced by 0%, 25%, 50%, and 75% glass powder (particle size < 600 μm). The obtained blocks were characterized by water absorption and compressive strength. All mixtures met the standard requirement for water absorption (< 10%), with values ranging from 6.0 to 7.5%. In terms of compressive strength, the replacement of sand with glass powder led to a statistically significant improvement (p ≤ 0.05) in all substitution levels. The average compressive strength increased by 32 to 35% compared to the control mix (3.11 MPa at 28 days), with the highest value reaching 4.35 MPa at 56 days for the 50% replacement. Furthermore, only the 50% mix achieved the minimum characteristic compressive strength required by Brazilian standards (fbk ≥ 3 MPa), with 3.62 MPa. The results support the industrial use of glass powder as a sustainable alternative to natural sand, promoting the reuse of long-neck glass bottles and reducing environmental impact.