Recycling pulverized concrete as cementitious precursor in alkaline one-part cements, with a waste glass-based sodium silicate

This study investigates the recycling of pulverized hardened concrete (PHC) as a cementitious precursor in one-part alkali-activated cements. Two sodium silicate activators were compared: a commercially available option and an alternative derived from waste glass. Pastes with varying PHC:activator ratios (70:30 to 90:10) were cured for 24h at 20, 60 and 80 °C, then completed 28-days at 20 °C in air and underwater. Higher initial curing temperatures promoted early strength, but all pastes exhibited continued hydration and strength gains at 20 °C. All pastes displayed hydraulic characteristics. The PHC with the waste glass-based activator achieved 28-day compressive strengths up to 20 MPa for 70–80% PHC. These cements showed significantly lower CO 2 emissions, embodied energy, and cost compared to those prepared with the commercial activator and a Portland cement. This research lays the groundwork for further investigations on sustainable precursors and activators in alkali-activated cements, aiming to optimize binder properties for broader applications.