An Exploration of Mechanochemical Activation on Various Potential Supplementary Cementitious Materials

Abstract

The use of supplementary cementitious materials (SCMs) is a major way to reduce the carbon footprint of concrete. Mechanochemical activation (MCA) can be used to activate inert materials that can then be used as SCMs. In this study, the effect of MCA using a planetary ball mill was investigated for 16 materials, ranging from natural occurring materials to by-products from various industries. In general, MCA caused the formation of nanoparticles, which were aggregated (rigidly bound) and agglomerated (loosely bound). Increased particle sphericity was also observed from scanning electron microscopy data. Additionally, the amorphous content, Brunauer–Emmett–Teller (BET) specific surface area, and total pore volume increased for after MCA respectively by 29%, 172%, and 427% on average. We demonstrated that initially reactive materials show modest increases (92% average increase) in reactivity after MCA. In contrast, inert materials experience a much greater increase (1126% average increase) depending on their chemical composition, amorphous content, BET specific surface area, and phase hardness. From the tested materials, all initially inert ones were transformed into reactive SCMs after MCA. Under the same MCA grinding conditions, pre-MCA reactivity can be used to predict post-MCA reactivity.