Studying the role of fine materials characteristics on the packing density and rheological properties of blended cement pastes

Abstract This study explores the use of ten different fine materials to partially substitute cement, aiming to reduce greenhouse gas emissions from cement production. The materials include two types of fly ash (coarse and fine), blast furnace slag, silica fume (SF), three grades of limestone powder (coarse, medium, fine), and three grades of quartz powder. The physical, chemical, and mineralogical properties of these materials were analyzed, and 51 cement pastes were produced to study the effects of particle characteristics on packing density (PD) and fresh paste properties. Parameters such as particle size distribution, specific surface area, and particle shape were examined in relation to PD, flowability, and rheological behavior (yield stress and plastic viscosity). Both the De Larrard and centrifugal consolidation methods were used to measure PD. The experimental results revealed that the incorporation of coarse limestone powder increases the PD to 61.5%, while the addition of fine quartz powder decreases it to 55.1%. SF increases the PD up to 10% replacement; however, with excess content, it decreases due to the high fineness of the particles. Additionally, SF pastes exhibited the lowest flow spread, 112 mm (62% of the reference paste). Plastic viscosity increases with the use of fine fly ash and SF due to the high surface area and fine particles. Fly ash and limestone powder can be used to replace cement by up to 50% without deteriorating the rheological properties and flowability of cement pastes.