Rheological Characterization of Cement Filler with the Building Material Cell
Building materials, such as gypsum, plasters, self-leveling screeds or cement need specific flow properties, as well as good standing or leveling behavior. Rheological investigations are therefore of great interest. The building material cell (BMC) is specially designed to measure building materials with rather large particles and to avoid measurement artefacts such as wall slip.
Introduction
To ensure product quality or to research new formulations, viscosity and visco-elastic properties can be monitored using a Modular Compact Rheometer (MCR) from Anton Paar equipped with a Building Material Cell (BMC).
The BMC consists of a metal cup with an inserted and removable cage. This cage prevents the sample from sliding alongside the inner wall, which is referred to as wall slipping.
The cup is surrounded by an insulating material to maintain temperature better and is mounted on an inset peltier plate, which can heat the sample up to 90 °C.
The standard measuring geometry is a two blade stirrer with open blades.
Samples should not contain particles larger than 4 mm in diameter, as this is the size of the gap between the stirrer blade and the cage. A volume of approximately 400 mL is required to fill the cup properly.
Typical samples which are measured in the BMC could be:
- Cement plasters
- Gypsum plasters
- Floor screeds
- Mortars
- Slurries
With the BMC and an MCR, different tests are possible. The most common ones used are:
- Shear-rate dependent viscosity measurements
- Shear stress ramps to determine yield points in rotation
- Amplitude sweeps
- Time- or temperature-dependent tests to follow curing/setting reactions and determine the pot life or to measure thixotropic behavior.
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