Development of standard reference materials for rheological measurements of cement-based materials

Rotational rheometers are routinely used for homogeneous materials, but their usage for characterization of a granular fluid like concrete is a relatively new phenomenon. As measurements with rheometers can involve flow in a complex geometry, it is important that they are calibrated with a reference material or an SRM. NIST has produced an SRM for cement paste (SRM 2492) as the first step for the development of a reference material for concrete rheometers. The second step is the development of a reference material for mortar, composed of the SRM 2492 with added spherical beads. Here, material properties, such as viscosity, cannot be measured in fundamental units with certainty, thus modeling was used to determine the plastic viscosity of the SRM mortar which in turn could be compared with experiments. This paper will present the process used to develop the mortar reference material. Measurements and modeling will be presented.