Binary effect of silica fume and waste glass powder as a cement replacement for a sustainable concrete

One promising implementation entails the utilization of silica fume and waste glass powder. This study aims to examine the impact of incorporating twelve different combinations of Glass Powder (GP) and Silica Fume (SF) as partial cement replacements in concrete mixtures. The experimental proportions include individual replacements of GP (5%, 10%, 15%, 20%) and SF (5%, 10%, 15%, 20%), along with blended combinations (GP 20%-SF 20%, GP 10%-SF 10%, GP 20%-SF 10%, GP 10%-SF 20%, GP 15%-SF 15%, GP 15%-SF 5%, and GP 5%-SF 15%). A thorough experimental investigation was conducted to examine key concrete properties, encompassing fresh state (workability), hardened state performance (compressive and tensile strength), durability indicators (water absorption and density), microstructural features (SEM), and elevated temperature resistance. Among the tested mixes, mix 10 (20% GP & 20% SF) demonstrated the highest slump compared to the control mix. Meanwhile, mix 5 (15% SF) achieved the greatest compressive strength, showing a 9.5% improvement over the control mix. This enhancement is due to the pozzolanic reaction of silica fume and glass powder, which refined the microstructure, thereby increasing strength. In terms of splitting tensile strength, mix 5 (15% SF) again performed the best, with a 13.3% increase over the control mix. On the other hand, mix 4 (15% GP) had the highest density, exhibiting a 2.6% rise compared to the control. Additionally, mix 3 (10% SF) displayed the lowest water absorption, attributed to the filler effect and pozzolanic activity, which sealed voids and densified the matrix, reducing water penetration into the samples. At 400 °C, mix M10 exhibited the highest residual compressive strength of 46.32 MPa, relative to the 28-day strength of the unexposed control, whereas mix M5 showed the lowest value of 38.34 MPa. This study demonstrates that incorporating GP and SF enhances concrete performance, reduces environmental impact, and offers a sustainable and practical solution for modern construction applications.