Effects of size fraction on composition and fundamental properties of Portland cement

To characterize roles of size fraction of Portland cement to its properties, Portland cement was classified into several fractions by air classifier. Then composition and hydration related properties of each Portland cement fraction were investigated. The results show deviation of chemical and mineral compositions occurs during classification. Both fine and coarse Portland cement fractions have undesirable strength contribution. Portland cement fractions falling in the range of 8–24 μm have low water requirement, high hydration rate and highest 28 days compressive strength. Thus Portland cement is recommended to be arranged in middle fraction (8–24 μm), while high activity supplementary cementitious materials (SCMs) and low activity SCMs (or inert fillers) are suggested to be arranged in fine and coarse fractions, respectively, by which Portland cement can be replaced by SCMs (or inert fillers) in larger extent without or with little performance loss.