The rheology of fresh high-performance concrete

✍ Scribed by Chong Hu; François de Larrard

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 703 KB
• Volume: 26
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(95)00213-8

✦ Synopsis

The rheological properties of fresh high-performance concrete were investigated with a new rheometer for concrete, BTRHEOM. It was found that, in a steady state, this category of concrete, without or under vibration, behaves as a Bingham material, and can be characterized by the shear yield stress (in Pa) and the plastic viscosity (in Pa.s). For the tested concretes, vibration reduced the yield stress to about half that without vibration, but little influenced the plastic viscosity. A new method for characterizing the evolution of workability is presented, which emphasizes an increase of the shear yield stress versus time. The thixotropy of concrete was confirmed, and it was noted in particular that the yield stress of a concrete after a resting period, called resting yield stress, can be several times that of the concrete in a steady state. The dilatancy of concrete was observed in some tests. Several factors influencing this phenomenon are discussed. Finally, a model is proposed for estimating the plastic viscosity of highperformance concrete from the mixture proportions.