In this presentation, I will give an overview of our project to improve the measurement science of fresh cement and concrete through computer simulation. Both the science we are studying and the computational algorithms we use will be described.

Concrete is a dense suspension of aggregates in a non-Newtonian fluid matrix with aggregates that span many decades in size. Additionally, there is also a large shape variation that cannot be accounted for by modeling the aggregates as idealized spheres. As you mix a batch of concrete, the torque required to mix the ingredients changes as the aggregates form and destroy structures within the material. The result is that it is nearly impossible to create a concrete rheometer that has a simple geometry such that analytical solutions relating torque and rotational velocity to actual rheological parameters are possible. Therefore, it is necessary to model the flow in these rheometer geometries in order to correctly interpret measurements in terms of fundamental units.

Our simulations model the flow of dense suspensions in candidate rheometers (e.g., vane) in order to link measurements (torque and angular velocity) from the concrete rheometer with fundamental rheological parameters (viscosity and yield stress). Further, analysis and visualization of the simulated flows will enable us to develop a fundamental framework to understand important physical mechanisms that control the flow of such complex fluids systems. Results from this study will advance the science of granular fluids and improve measurement science for rheometer design for granular fluid systems.