Re-Certification of SRM 2492: Bingham Paste Mixture for Rheological Measurements
Chiara F. Ferraris, Alex Olivas, William F. Guthrie, Blaza Toman
Rheological measurements are often performed using a rotational rheometer. In this type of rheometer, the tested fluid is sheared between two surfaces, one of which is rotating . Usually, an angular velocity is imposed on the fluid (through the rotating surface) and this angular velocity determines the shear rate the fluid is subjected to. The response of the material is monitored by the measurement of the resultant torque on the shaft of the rheometer; this torque can then be converted to shear stress. In order to calibrate a rheometer, a standard oil of known viscosity should be tested in the rheometer to verify that the instrument is operating correctly. However, these standard oils are expensive; which makes it impractical for use in calibrating with the rheometer with a large capacity as needed for concrete. The report SP 260-174 Rev.2012  describes how this SRM 2492, a Bingham Paste Mixture for Rheological Measurements was developed and provides all the details on the various ingredients. After an inter-laboratory study under the sponsorship of the American Concrete Institute (ACI) committee 238, Workability of Fresh Concrete, it was found that the instructions provided to prepare the SRM were inadequate to obtain reproducible data in all laboratories. Thus after establishing a better preparation method, new instructions were drafted and it was found that the certified values were no longer valid. Thus, it was necessary to redo a series of testing to obtain a new certified value. This report provides all measurements obtained, the calculation of the new rheological characteristics and the statistical analyses.
, Olivas, A.
, Guthrie, W.
and Toman, B.
Re-Certification of SRM 2492: Bingham Paste Mixture for Rheological Measurements, Special Publication (NIST SP), National Institute of Standards and Technology, Gaithersburg, MD, [online], https://doi.org/10.6028/NIST.SP.260-182
(Accessed June 18, 2021)