First step in modeling the flow table test to characterize the rheology of normally vibrated concrete

A precise measurement of the rheological properties of concrete is the first step to quantitatively evaluate the placing and casting process. Both yield stress and plastic viscosity of flowable concrete can be conveniently estimated through a model correlating them with the slump flow test results. However, there has been no report on estimating the plastic viscosity of normally vibrated concrete and that of mortar constituting the concrete. This paper provides a model using the flow table test, specified in ASTM C 1437, to estimate the Bingham parameters of mortar. The model is based on the volume-of-fluid simulations of a non-Newtonian non-thixotropic homogeneous fluid. The estimated Bingham parameters are compared with the measurements obtained using two commercial rheometers. The bias of rheological measurement and effect of mortar film thickness on rheology are also discussed. Finally, the Bingham parameters of wet-sieved mortar allows us to characterize the range of Bingham parameter of mortar constituting normally vibrated concrete.