Concrete rheometer

This paper describes a concrete rheometer based on the BTRHEOM design and presents equations to compute shear stress and strain rate from the measured values of torque and angular velocity. The influence of the boundary layer at the outer wall of the rheometer on the measured concrete flow behaviour is assessed. Different materials at the wall are shown to have significant effects on the values of yield stress and plastic viscosity, and results show it is reasonable to presume that the boundary layer is paste. It was found experimentally that the height of the gap between the top and bottom plates affects the measured torque and measured strain rate but has little effect on apparent viscosity.