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Title: Lessons Learned from RILEM TC MRP Round-Robin Testing of Concrete and Mortar Rheology in Bethune France, May 2018

Author(s): Vanhove

Publication: Web Session

Volume: ws_S22_Vanhove.pdf

Issue:

Appears on pages(s):

Keywords:

DOI:

Date: 3/28/2022

Abstract:
There are several concrete rheometers used around the world that have significant design differences, but no standard method with which to compare their results. As demonstrated from two interlaboratory testing campaigns held in 2000 and 2003, different concrete rheometers can deliver different results. A new campaign was therefore executed in 2018, focusing on more flowable concrete mixtures and different procedures. This new Round Robin tests help to bring to light systematic sources of error and can give rise to the necessary corrective action. In fact, not all rheometers measure the same values, which can be due to the equipment (sensors, registration, calibration) and the imperfect flow profiles induced in each rheometer. Measuring the rheological properties of flowable concrete mixtures is not a straightforward task. Procedures need to be adjusted to match the conditions we impose (e.g.: we matched shear rates by theoretical calculations). A difference in procedure induces a difference in results what has been observed by comparing a different procedure with the standard one. Unfortunately, there is no single procedure that works for all rheometer and there is no rheometer setting that works for all materials. We need to make sure all procedures are able to capture the data we need. In fact, we observed that the peak for static yield stress can be sometimes missing with one of the devices. Another important observation noted is the deviation in the measurement which is more dependent on the material than on the rheometer types. Especially aggregate content, yield stress and viscosity affected variations around the expected values. Round robin tests have come to be regarded as an important method both to improving jointly defined test procedure but also to give information about variability in equipment, the reproducibility and repeatability of the test method.