A discussion of the paper “Influence of natural pozzolan, colemanite ore waste, bottom ash, and fly ash on the properties of Portland cement” by Ş. Targan, A. Olgun, Y. Erdogan, and V. Sevinc

This discussion paper comments on a study of the effects of natural pozzolan, colemanite ore waste, bottom ash, and fly ash on the properties of Portland cement (PC). This commentator states that the original article should have clarified the chemical effects of pozzolanic materials on crystal formation and development during the hydration process. The commentator notes that the addition of pozzolanic blending agents, each different in composition, introduces a great diversity into cement systems. In addition, mechanical interlocking plays a significant role in chemical forces during crystal formation and development.