Influence of Aggregate Volume Fraction on Concrete Pumping Behaviour

The paper at hand quantifies the influence of aggregate volume fraction on pumping behaviour of concretes with distinct flow behaviours, i.e. plug or shear flow type. For this purpose, conventionally vibrated concretes (CVC), and self-compacting concretes (SCC) containing different volume fraction of aggregates are designed, and their rheological properties are investigated. The results indicate that the concrete pumpability, in terms of delivery rate for a given pressure, decreases by at least 30% for 10% increase in aggregates content by volume. The relative decrease in pumpability is more pronounced for CVC. Furthermore, it is shown that under certain experimental conditions the rheological properties of the lubricating layer (LL) can be approximated to those of the constitutive mortar in pumped concrete. Accordingly, the measurements on constitutive mortar can be used as a basis for the analytical prediction of pumping pressure. The obtained knowledge is a prerequisite for evaluating flow-induced particle migration (FIPM) during pumping and LL formation.