Investigation on the influence of granular packing on the flow properties of cementitious suspensions

Fresh concrete can be considered as a suspension of grains of various sizes in a continuous fluid phase. The rheological properties of fresh concrete greatly depend on the physical factors, chemical and mineralogical characteristics of the fine components. Interparticle interactions occur during flow and modify the apparent rheological behaviour. Therefore, a thorough understanding of the rheological behaviour of cementitious suspensions with respect to particle packing is required. The objective of this study is to characterise the interrelationship between the flow properties and the particle packing density of the cementitious suspensions. The experimental investigation included Puntke tests for determining the packing density, and rheological tests that were performed in a rheometer for the characterisation of cement and silica fume (C + SF) as well as cement and fly ash (C + FA) mixtures. The effect of the water to powder ratio (w/p ratio) and the packing density on the flow properties of the cementitious suspensions was studied. From the study, it was observed that a good correlation exists between the w/p ratio and the yield value (g) for both C + SF and C + FA mixtures. The packing density shows a marked influence on the value of g for both mixtures, but has less influence on the value of plastic viscosity (h) for C + FA mixture.