Rheological, mechanical and fire resistance performance of waste glass activated geopolymers for concrete 3D printing

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. .