LAUSR

Abstract Currently, construction and demolition waste (CDW) is the most generated waste worldwide. In Colombia, ~ 22 million tons of CDW are generated per year, of which 1.0 million tons are generated in Santiago de Cali; therefore, the mitigation and reuse of CDW are important for reducing the environmental impact of the construction sector. This article presents a study on the application of CDW alkaline activation technology for the manufacture of pastes and mortars using alkaline activators with lower environmental impact, such as sodium sulfate and sodium hydroxide. Geopolymeric pastes were produced using a mixture of 80%CDW-20%OPC and activator solutions with concentrations of Na2O between 0.44% and 1.31%. The pastes were manufactured with fine aggregate obtained from the same CDW. The materials developed were characterized microstructurally, physically and mechanically. The scanning electron microscopy (SEM-EDX) and XRD results, the reaction products were C-(A)-S-H, C-S-H gels and minority (N),C-(A)-S-H gel. Additionally, in the sodium-sulfate-activated pastes, ettringite was identified as an additional hydration product through SEM and X-ray diffraction (XRD). Binders activated with sodium sulfate 0.8% Na2O (solid-state activator) yielded compressive strengths up to 18 MPa for pastes. These results provide an opportunity for the potential reuse of CDW in new eco-friendly binders.