This report presents the results of an experimental program dealing with the rheology of fresh concrete. The three main goals were: 1) Obtain rheological data on concretes produced with various mixture compositions; 2) Establish models to link mixture composition with rheological properties; 3) Develop a new simple field test that will determine rheological parameters. Approximately 80 mixtures (mortars and concretes, with and without superplasticizer) were formulated and tested using a BTHREOM rheometer, with parallel tests on the slump cone. It appears that the relationship stress and strain rate for concrete is non-linear. A description of the behavior of the material that is better than the usual linear Bingham approach is provided by the Herschel-Bulkley model. Using the data obtained, the rheological characteristics of the mixtures as a function of their composition were modeled. A physical interpretation of the results is proposed. Finally, the development of a simple job-site test for estimating yield stress and viscosity is described. The results of this test for all mixtures used in the program were analyzed. Semi-empirical models are proposed for the yield stress and for the plastic viscosity.
and DeLarrard, F.
Testing and Modeling of Fresh Concrete Rheology, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.IR.6094
(Accessed December 2, 2023)