Abstract
This study investigates the effect of incorporating 20 wt% ground granulated blast furnace slag (GGBFS), ground waste bottle glass (GWBG) and metakaolin (MK) on the hydration behavior, mechanical and environmental performance of blended cements cured at 23 °C ± 2 °C for 7, 28, and 90 days. Mechanical performance was evaluated using the strength activity index (SAI), while environmental performance was assessed through heavy metal leaching and a preliminary sustainability screening. The tested mortars achieved SAI values greater than 80% at all curing ages, consistent with the observed development of hydration products and microstructural evolution. Heavy metal leaching tests showed Pb and Zn below the limit of detection, while Cr release ranged from 0.70 to 1.15 mg/kg, which is substantially below the non-hazardous waste acceptance limit. The preliminary sustainability screening showed reductions of 10.9%–17.2% in calculated binder-production embodied energy and 12.9%–18.9% in calculated binder-production CO 2 emissions compared to a plain Portland cement benchmark. These findings demonstrate the potential of these SCMs for producing blended cements with satisfactory mechanical performance, limited trace-metal release, and lower calculated binder-production CO 2 indicators compared with the plain Portland cement benchmark.