The Application of Rheological Concepts on the Evaluation of High-Performance Concrete Workability

Traditionally, concrete workability is associated with its consistency, expressed in terms of the value measured by the slump test that, in spite of being a commonly used test, does not quantify it totally. It happens because, from a rheological point of view, the fresh concrete flows as a liquid and its behavior is similar to a Bingham fluid, being described by two rheological parameters: yield stress and plastic viscosity. Thus, this paper presents the evaluation of high-performance concrete workability by the traditional slump test and by the rheometer. The process of workability loss is associated with the increase of rheological parameter values and to a corresponding reduction of the slump value over time. The correlation among the parameters obtained by the rheometer and the value measured by the slump test showed that the slump value is much more sensitive to the yield torque than the torque viscosity.