ICAR Plus Rheometer

The ICAR Plus is designed to characterize the static yield stress, the dynamic yield stress and plastic viscosity of the concrete. A high static yield stress is desirable because it reduces formwork pressure and increases the resistance to segregation. But for ease of pumping, placement and self-consolidation, a low dynamic yield stress is necessary. The dynamic viscosity provides cohesiveness and reduces segregation when concrete is flowing. Thus by determining the dynamic flow curves of concretes mixtures and optimum balance between ease of flow and resistance to segregation can be realized. These types of determinations cannot be done using conventional slump-based tests.

The ICAR Plus is composed of a container to hold the fresh concrete, a driver head supported on a frame with an electric motor and torque meter, a four-blade vane and a laptop computer to operate, record the torque  and calculate the flow curve parameters. The size of the container and vane are selected based on the nominal maximum size of the aggregate.

Two types of tests are performed: stress growth test at a constant slow speed where the maximum torque measured is used to calculate the static yield stress; and the flow curve test to determine the dynamic yield stress and the plastic viscosity (Bingham parameters).