High-porosity alkali-activated binders based on glass and aluminium recycling industry waste.

Abstract

The potential as alkali-activated precursors of ceramic-stone-porcelain (CSP) and PAVAL, two residues derived from the optical separation of glass cullet and salt slag from secondary aluminium recycling, has been assessed. Alkali-activated CSP and PAVAL binders' formulations were prepared using NaOH 4 M and 6 M as alkaline activator solutions. The effect of the Na2O/Al2O3 ratio and alkaline activator concentration was evaluated from a chemical, physical, mechanical, and environmental perspective. The results revealed the formation of secondary reaction products attributed to the formation of (C,N)-A-S-H gels. It also showed the influence of decreasing Na2O/Al2O3 ratio in the obtained binders, increasing porosity and affecting the mechanical performance. Besides, it was demonstrated that PAVAL acts as a precursor and pore-generator. Finally, the environmental characterisation showed a significant leaching concentration of heavy metal(loid)s such as As, Cr, Mo, Sb, and Se, which decreases with longer curing periods.