Return to Part I Chapter 2 Sec. (4a) Return to Table of Contents
F. de Larrard
Laboratoire Central des Ponts et Chaussées (LCPC), Paris, France;
Guest researcher at National Institute of Standards and Technology (NIST), Gaithersburg, Maryland, USA
Some preliminary results of an experimental program on the rheological behavior of fresh concrete are presented. In the rheological tests, performed with a plane-to-plane rheometer, it appears that the relationship between torque and rotation speed is not exactly linear. The fresh concrete behavior is better described by the Herschel-Bulkley model: = '0 + a b ; and are the shear stress and the strain gradient applied to the specimen, respectively. '0, a and b are three material parameters describing the concrete behavior. Among other advantages, this new description avoids the problem of negative yield stress encountered with the Bingham model.