Degradation of alkali-activated Fe-rich slag in acetic acid

Abstract

Alkali-activated Fe-rich non-ferrous metallurgical slags (AA-NFMS) emerge as a novel, sustainable cementitious binder, but durability performance is one of the crucial parameters to assess their success. This paper investigates the degradation mechanisms of AA-NFMS in 4 wt% acetic acid (AcH) solutions, commonly found in agricultural industries. The results indicated that upon AcH exposure, the amorphous structure of AA-NFMS is changed. This process is accompanied by the release of crucial elements, including Ca, Fe, and a smaller amount of Al and Si, resulting in the formation of a more polymerized network. Fe could precipitate near the formed cracks. EPMA and micro-CT revealed the important role of crack formation and the initial permeability of AA-NFMS on the degradation process. Additionally, strength change does not correlate with mass change but is closely related to the permeability. Notably, AA-NFMS with 10 wt% CaO demonstrates the highest strength after AcH exposure.