Rheological behavior of cement pastes from MRI velocimetry

• Published in: Cement and concrete research Vol. 35; no. 10; pp. 1873 - 1881
• Main Authors: Jarny, S., Roussel, N., Rodts, S., Bertrand, F., Le Roy, R., Coussot, P.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Ltd 01.10.2005; Elsevier Science; Elsevier
• Subjects: Applied sciences; Buildings. Public works; Cement concrete constituents; Cement paste; Cements; Engineering Sciences; Exact sciences and technology; Magnetic Resonance Imaging; Materials; Measurements. Technique of testing; Physical properties; Properties and test methods; Properties of anhydrous and hydrated cement, test methods; Reactive fluid environment; Rheology; Magnetic Resonance Imaging; Rheology; Physical properties; Cement paste; Measuring instrument; Experimental result; Magnetic resonance; Water content; Shear stress; NMR spectrometry; Experimental study; Steady state
• ISSN: 0008-8846; 1873-3948
• DOI: 10.1016/j.cemconres.2005.03.009

From MRI measurements, it is shown that in a flowing cement paste the thixotropic effects dominate over short time scales, while aging effects become significant over larger timescales. The steady state behavior, defined as flow properties in the intermediate period, exhibits a yielding behavior which differs from the prediction of usual yield stress models. The transition from the “solid” to the “liquid” regime is abrupt: the shear rate changes suddenly from zero to a finite value (critical shear rate) when the shear stress overcomes a critical value. These critical shear rates and shear stresses are independent of the flow conditions so that they may be considered as intrinsic material parameters. It was also shown that these results are consistent with usual macroscopic observations from conventional rheometry.