Title:
A New Rheometer for Soft-to-Fluid Fresh Concrete
Author(s):
F. de Larrard, C. Hu, T. Sedran, J. C. Szitkar, M. Joly, F. Claux, and F. Derkx
Publication:
Materials Journal
Volume:
94
Issue:
3
Appears on pages(s):
234-243
Keywords:
dilatancy; fluid concretes; fresh concretes; workability;
high-performance concretes; plastic viscosity; pumping; rheology;
shear yield stress; superplasticizers; thixotropy;
DOI:
10.14359/304
Date:
5/1/1997
Abstract:
This article describes the development of apparatus designed to characterize the rheological behavior of fresh concrete, both in the lab and on site, in the range of consistency from soft to fluid. The principles that governed the design of the rheometer are first recalled. It is a torsional rheometer, in which a sample shaped like a hollow cylinder is sheared between two horizontal planes. The conduct of the tests is then described, followed by their processing, which yields, in particular, two physical quantities to characterize a concrete, the shear yield stress (t0, in Pa) and the plastic viscosity (m, in Pa.s). These parameters may be measured with or without vibration, giving different values in each case. Later, the results of experiments are described. They deal with the detection, with only one sample, of the phenomenon of loss of workability, and with the pumpability of the concrete on site, respectively. The article concludes with a look at the prospects for industrial use of the BT RHEOM rheometer.