Mechanochemical activation of basaltic fines

Basaltic fines (BF) are a promising source of supplementary cementitious materials (SCMs) due to their worldwide availability, low cost, and adequate chemistry. However, they need to be processed to be used as SCMs, as they are otherwise inert. We explore mechanochemical activation (MCA), where raw materials are exposed to high-energy grinding, which increases powder fineness and amorphous content, thus activating them for use as SCMs. BF were characterized before and after MCA using various techniques. Reactivity was measured using the modified R³ test. Reactivity increased with increasing grinding time and ball-to-powder ratio, and beyond certain thresholds of time, activation beyond an inert threshold occurred. Partial amorphization of the powders was evident from X-ray diffraction. Electron microscopy revealed the formation of rounded particles, and particle aggregation and agglomeration. Laser diffraction showed a b-modal or tri-modal particle size distribution. Reactivity was strongly correlated to the amorphization, but not to the increased specific surface area.