Alkali-activated binders based on the coarse fraction of municipal solid waste incineration bottom ash

The potential of the least polluted fraction (from 8 to 30 mm) of municipal solid waste incineration (MSWI) weathered bottom ash (WBA) as an alkali-activated cement precursor was evaluated. Alkali-activated WBA binders (AA-WBA) formulations were prepared through alkali-activation of WBA as sole precursor. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) mixtures with different pH's were used as alkali-activator solution. The effect of alkali-activator solution pH on the final properties was assessed. Results showed the hydrolytic stability of all formulations. The selective chemical extractions and physicochemical characterisation revealed the formation of the C-S-H, C-A-S-H, and (N,C)-A-S-H gels. The promising compressive strength results demonstrated the potential of AA-WBA binders. The increase of pH in the alkali-activated solution promotes the formation of gel reaction products and enhance mechanical properties. This investigation promotes the green cements manufacturing and the use of secondary resources to reduce the impact of natural resources extraction used for the ordinary Portland cement (OPC) production. (C) 2020 SECV. Published by Elsevier Espa na, S.L.U.

Automated summary

This study evaluated the potential of the least polluted fraction of municipal solid waste incineration weathered bottom ash as an alkali-activated cement precursor and found that increasing the pH of the alkali-activator solution can enhance the mechanical properties.