On the Effect of Coarse Aggregate Fraction and Shape on the Rheological Properties of Self-Compacting Concrete

Rheological measurements have been undertaken to illustrate the applicability on fresh self-compacting concrete of a model for the relative viscosity and yield stress of suspensions. The model is based on linear viscoelasticity and classical theory for composite materials and it takes into account the amount, shape (aspect ratio of ellipsoids), and maximum packing density of the particles (here aggregates), as well as the rheological properties of the matrix (here mortar). Self-compacting concretes made from different types of coarse aggregates: spheres (glass beads), sea dredged, crushed, and a mix of sea dredged and crushed aggregates, have been tested in a coaxial cylinder concrete rheometer (BML). The investigations indicate that the aspect ratio, angularity, and surface texture of aggregates affect the viscosity and yield stress. The magnitude of these effects depends on the property in question, viscosity and yield stress.