Rheological, Mechanical and Fire Resistance Performance of Waste Glass Activated Geopolymers for Concrete 3D Printing (2025-07)¶

This study investigates the alkali activation of waste glass powder (WGP) for developing 3D printable geopolymer concrete. The rheological, mechanical, and fire-resistance of 3D printed concrete were evaluated to determine the effect of WGP as a partial substitution for fly ash in geopolymers. Rheological results show that incorporation of WGP reduces the rheological properties of printable mixes. For instance, the apparent viscosity of mixes containing 50% WGP was reduced by 48% at low shear rate (0.1 s−1), and 46% at high shear rate (100 s−1). The corresponding reductions in the dynamic yield stress and plastic viscosity were 35% and 55%, respectively, indicating improved flowability and pumpability. However, compressive strength declined with increased WGP. The 28-day mold-cast strength decreased from 51.4 MPa to 35.6 MPa at 50% WGP. In contrast, the elevated temperature properties are enhanced with reduced strength loss for the WGP incorporated specimens, attributed to the sintering effect of WGP.