Synthesis of Geopolymer Materials Based on Non-Ferrous Metallurgy Slag and Fly Ash Using Mechanical Activation

In this chapter, the effect of mechanical activation (MA) of non-ferrous metallurgy slag (Cu–Ni slag and Zn slag) and Class F fly ash in a planetary mill on their geopolymerization has been considered. MA of the Cu–Ni slag and Zn slag in CO₂ atmosphere considerably enhanced their reactivity with respect to the alkaline agent in comparison to the slag milled in air as was observed using isothermal conduction calorimetry. Accordingly, the geopolymers based on slag milled in CO₂ showed a higher compressive strength compared to those based on slag milled in air. MA of the Cu–Ni slag blended with alkaline earth metal carbonates exhibited a similar effect. Moreover, the mechanically activated mixtures of Cu–Ni slag with MCO₃ (M – Mg, Ca, Sr, Ba) displayed binding properties even without using an alkaline agent. It was shown that the performance of fly-ash-based geopolymers can be significantly improved by MA of the fly ash with the addition of natural carbonate minerals such as calcite and dolomite. In terms of geopolymer strength, the mixture of fly ash with calcite was preferable to that with dolomite, which can be explained by the higher content of calcium in the former mineral.