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

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.

Automated summary

The potential of ceramic-stone-porcelain (CSP) and PAVAL as alkali-activated precursors was evaluated. Alkali-activated CSP and PAVAL binders were prepared using NaOH as the alkaline activator. The effect of Na2O/Al2O3 ratio and alkaline activator concentration on the chemical, physical, mechanical, and environmental properties was investigated. The results showed the formation of secondary reaction products and the influence of binder composition on porosity and mechanical performance. Furthermore, PAVAL was found to act as a precursor and pore-generator. The environmental characterization revealed significant leaching concentration of heavy metal(loid)s, which decreased over time.