The role of supplementary cementitious materials in hydration, durability and shrinkage of cement-based materials, their environmental and economic benefits: A review

Due to strict environmental regulations, the construction sector has observed extensive use of supplementary cementitious materials (SCMs) in recent years. As a result, new alternative SCMs have emerged and research in this particular area has considerably developed. Although a large number of research devoted to cement-based materials blended with SCMs has been conducted, there continue to be debates about their characteristics, effects on the hydration, and the durability of cement pastes, mortars and concrete. Therefore, this review summarized the most widespread methods for SCMs characterization, major characteristics, and the role of each of the five widely used SCMs including coal fly ash, silica fume, ground granulated blast furnace slag, limestone powder, and metakaolin in the hydration and durability of cement-based materials. Ultimately, their environmental and economic advantages were also reviewed. A huge variation in the SCMs physical and chemical characteristics has been highlighted as the major concern when it comes to the establishment of standards and characterization methods. The literature has also shown that the hydration, compressive strength and durability of cement-based materials blended with SCMs typically depend on the replacement ratios, fineness and synergic effect of the SCMs' reactivity mechanisms. Owing to their high specific surface area and pozzolanic activity, partial cement replacement with a suitable amount of silica fume and metakaolin considerably accelerates the hydration and increases the heat of hydration of cement-based materials. Besides, limestone powder and ground granulated blast slag reportedly present better environmental and economic benefits compared to metakaolin and silica fume.