Comparative study of mechanical performance and durability of concrete incorporating supplementary cementitious materials

This study investigates different supplementary cementitious materials (SCMs) as partial substitution for Portland limestone cement in concrete. Five natural pozzolans (two grades of metakaolin, diatomaceous earth, wollastonite, and pumice) and three industrial by-products/wastes (recycled glass powder, Class F fly ash, and reclaimed fly ash) were tested for their chemical reactivity. Those that were classified as reactive were incorporated into concrete at 10, 20, or 40 wt.% of cement. According to results, concretes containing natural pozzolans required significantly higher contents of both superplasticizer and air-entraining admixture, while those with other SCMs required increases only in the air-entraining admixture. The natural pozzolans provided superior compressive strength and durability. The recycled glass powder did not perform as well as the natural pozzolans, however, provided better strength and durability than the fly ashes. The results highlight advantages of performance-based design when using alternative SCMs, especially with the scarcity and increasing price of conventional ones.