RILEM TC 266-MRP: round-robin rheological tests on high performance mortar and concrete with adapted rheology—rheometers, mixtures and procedures

Recent developments in understanding the rheology of mortar and concrete as well as applying this understanding in the practice of construction necessitate an accurate assessment of materials’ rheological properties. It is well known that different rheometers for mortar and concrete deliver different results, as this was shown over 15 years ago in two measuring campaigns comparing concrete rheometers. Considering newly developed rheometers, including those to evaluate interface rheology and structural build-up at rest, as well as additional measurement procedures and data interpretation techniques, a new comparison campaign was carried out in 2018 at the Université d’Artois, in Bethune, France. This new campaign focused on measuring workability characteristics, flow curves, static yield stress values, interface properties and tribological data. A total of 14 different devices capable of measuring one or more of the above-mentioned characteristics were employed. These devices included four ICAR rheometers, the Viskomat XL, the eBT-V, the RheoCAD (two geometries), the 4SCC rheometer (two geometries), the plate test, the sliding pipe rheometer, a tribometer and an interface tool for the ICAR rheometer. This paper describes the mixture design and rationale of the five investigated concrete and three investigated mortar mixtures, design and analysis of the experiments, and comparison of test results. The findings confirmed some of the conclusions from two previous testing campaigns and expanded the findings to more modern concrete mixtures and more diversified sets of rheological devices. The investigated rheometers yielded different absolute values for material parameters, but they all were able to similarly distinguish between mixtures qualitatively. For static yield stress and interface rheology measurements, similar conclusions were obtained as for flow curves.