A new gap-graded particle size distribution and resulting consequences on properties of blended cement

To improve the properties of blended cement and utilize cement clinker and supplementary cementitious materials (SCM) more efficiently, a new gap-graded particle size distribution (PSD) based on close packing theory was proposed, then blended cements with the gap-graded PSD were prepared by mixing cement clinker and SCM fractions homogeneously. The experimental results show gap-graded blended cement pastes present a lower water requirement, a higher packing density, and a more homogeneous, denser microstructure than reference cement (prepared by co-grinding). As a result, both early and late properties of the gap-graded blended cements with only 25% clinker content can be comparable with those of Portland cement. This investigation supports that a high performance blended cement with low clinker content can be prepared using the gap-graded PSD and arranging a high activity SCM, clinker, and a low activity SCM (or inert filler) in the fine, middle and coarse fractions, respectively.