Effect of high-energy mixing on hydration of amorphous and crystalline Portland cement phases: an X-ray diffraction study

Abstract High-energy mixing offers a novel approach to enhancing the efficiency of Portland cements that incorporate supplementary cementitious materials regarding the hydration time and compressive strength formation. This research focused on monitoring the formation and degradation of mineral phases, as well as the compressive strength development and heat flow of mortars, within the first 48 hours, using clinker-efficient Portland composite cements. This study involved mixing Portland cement containing 20 wt% amorphous blast furnace slag and 10 wt% limestone with water using three different high-energy mixing techniques. The results demonstrated that the compressive strength of the Portland composite cements was comparable to that of ordinary Portland cement within a 48-hour period. Rietveld refinement was employed to track the formation of portlandite and the sum of the amorphous phases quartz and tobermorite, as well as the degradation of tricalcium silicate. The decline in tricalcium silicate and the formation of Portlandite showed a significant increase in reaction speed due to high-energy mixing. Additionally, a reduction in calcite content was observed, suggesting that calcium carbonate contributes to the enhanced compressive strength observed within the first 48 hours.