Metakaolin-based alkali-activated binders incorporating limestone and lime mud

This study investigates the effects of partially replacing metakaolin with limestone and calcium carbonate mud (lime mud) in alkali-activated binders. A comprehensive set of analyses was conducted, including rotational rheometry, isothermal calorimetry, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and environmental impact assessments. The incorporation of limestone or lime mud resulted in a progressive decrease in yield stress and viscosity compared to the reference paste. FTIR spectra confirmed the occurrence of geopolymerization at both 7 and 28 days. Mechanically, the binders containing lime mud exhibited performance comparable to or exceeding those with limestone. A reduction of up to 25% in CO 2 emissions was achieved with the highest lime mud replacement level. However, due to the high environmental burden of the alkaline activators, no significant reduction in embodied energy was observed. Despite this limitation, the study demonstrates the potential for incorporating industrial waste into alkali-activated systems, contributing to waste valorization and a reduction in the environmental footprint associated with their disposal.