Fresh State Performance of Concrete with Recycled Glass Powder as Cement Replacement and Nanosilica

This study evaluated the combined effect of recycled glass powder (RGP) and nanosilica on the fresh-state properties of concrete. Mixtures were prepared with partial cement replacements of 10%, 15%, and 20%, incorporating nanosilica at 1.5 % by cement weight. The control mixture (RGP-0) does not include nanosilica, allowing comparison with the additive-containing mixtures. Results showed that RGP-10 improved workability, achieving a slump of 22.6 cm compared to 7.0 cm for RGP-0, while RGP-15 and RGP-20 exhibited only slight reductions in fluidity. Air content decreased in RGP-10, RGP-15, and RGP-20, with values of 1.6 %, 1.9 %, and 1.7 %, respectively, compared to 2.3 % in RGP-0, indicating that the mixtures with RGP and nanosilica develop a denser matrix with reduced void formation. Additionally, nanosilica accelerated early hydration, raising the initial temperature by up to 3.5 °C in RGP-20 without affecting workability. These findings demonstrate that moderate cement replacement with RGP and nanosilica can produce more stable, homogeneous, and sustainable concretes, providing useful insights for designing mixtures with improved fresh state performance.