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Marina Neophytou, Stella Pourgouri, Antonis Kanellopoulos, Michael Petrou, Ioannis Ioannou, Georgios Georgiou, Andreas Alexandrou
Determination of the rheological parameters of self-compacting concrete matrix using slump flow test

Appl. Rheol. 20:6 (2010) 62402 (12 pages)

The classification of a concrete mixture as self-compacting (SCC) is performed by a series of empirical characterization tests that have been designed to assess not only the flowability of the mixture but also its segregation resistance and filling ability. The objective of the present work is to correlate the rheological parameters of SCC matrix, yield stress and plastic viscosity, to slump flow measurements. The focus of the slump flow test investigation was centered on the fully yielded flow regime and an empirical model relating the yield stress to material and flow parameters is proposed. Our experimental data revealed that the time for a spread of 500 mm which is used in engineering practice as reference for measurement parameters, is an arbitrary choice. Our findings indicate that the non-dimensional final spread is linearly related to the non-dimensional yield-stress. Finally,there are strong indications that the non-dimensional viscosity of the mixture is associated with the non-dimensional final spread as well as the stopping time of the slump flow; this experimental data set suggests an exponential decay of the final spread and stopping time with viscosity.

Cite this publication as follows:
Neophytou M, Pourgouri S, Kanellopoulos A, Petrou M, Ioannou I, Georgiou GC, Alexandrou A: Determination of the rheological parameters of self-compacting concrete matrix using slump flow test, Appl. Rheol. 20 (2010) 62402.

Evdokia Achilleos, Georgios C. Georgiou, Savvas G. Hatzikiriakos
On numerical simulation of polymer extrusion instabilities

Appl. Rheol. 12:2 (2002) 88-104

The objective of this study is mainly to review recent work concerning the numerical modeling of the stick-slip and gross melt fracture polymer extrusion instabilities. Three different mechanisms of instability are discussed: (a) combination of nonlinear slip with compressibility; (b) combination of nonlinear slip with elasticity; and (c) constitutive instabilities. Furthermore, preliminary numerical simulations of the time-dependent, compressible extrudate-swell flow of a Carreau fluid with slip at the wall, using a realistic macroscopic slip equation that is based on experimental data for a high-density polyethylene, are presented.

Cite this publication as follows:
Achilleos E, Georgiou GC, Hatzikiriakos SG: On numerical simulation of polymer extrusion instabilities, Appl. Rheol. 12 (2002) 88.

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