Method for calculating dynamic yield stress of fresh cement pastes using a coaxial cylinder system

Peng, Y., Ma, K., Unluer, C. , Li, W., Li, S., Shi, J. and Long, G. (2021) Method for calculating dynamic yield stress of fresh cement pastes using a coaxial cylinder system. Journal of the American Ceramic Society, 104(11), pp. 5557-5570. (doi: 10.1111/jace.17979)

Abstract

The calculation of the rheological parameters of fresh cement pastes plays a key role in understanding the rheology of cement-based mixes. Because cement paste is not a simple Bingham fluid, a suitable nonlinear model must be found for characterizing its flow. A test system in which the rotational speed or shear rate can be changed in multiple steps is regarded as a suitable rheological test protocol because the paste reaches a steady state. Furthermore, theoretical derivations show that the solution of the Couette inverse problem corresponding to the modified Bingham model and the Herschel–Bulkley (H-B) model is complex. However, a comparative analysis revealed that the yield stress of fresh paste could easily be obtained through a calculation process based on a Parabolic model. This study presents the complete calculation procedure for this model. The influence of the plug flow is considered, and test points with low minimum shear stress (τmin) are excluded. Finally, the accuracy of the proposed method is verified through comparisons with the results obtained using mini-cone slump tests. These results show that the dynamic yield stress calculated using the expression of the Couette inverse problem based on the Parabolic model in consideration of the plug flow is very close to the yield stress obtained using the mini-cone slump flow test. This proves that the proposed method could precisely characterize the dynamic yield stress of cement pastes.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Unluer, Dr Cise
• Authors: Peng, Y., Ma, K., Unluer, C., Li, W., Li, S., Shi, J., and Long, G.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Journal of the American Ceramic Society
• Publisher: Wiley
• ISSN: 0002-7820
• ISSN (Online): 1551-2916
• Published Online: 19 June 2021
• Copyright Holders: Copyright © 2021 The American Ceramic Society
• First Published: First published in Journal of the American Ceramic Society 104(11): 5557-5570
• Publisher Policy: Reproduced in accordance with the publisher copyright policy