The main objective of this study is to evaluate the workability of fresh portland cement concrete while it is still in the mixing truck by determining fundamental rheological parameters (plastic viscosity and yield stress). Nine concrete mixtures with different yield stress and viscosity were tested in a concrete truck. The measurements made with the truck were based on the typical method of determining the flow behavior in a traditional fluid rheometer; that is, the shear rate in the mixing truck was swept from high to low by varying the rotation speed of the drum. The results of these experiments are discussed and compared with data provided by the ICAR rheometer, a new portable rheometer designed for measuring concrete rheology. The test results indicate that the mixing truck is sufficiently sensitive to detect differences in yield stress, slump, and plastic viscosity. However, the plastic viscosity determined by the truck measurement is not correlated with plastic viscosity from the ICAR rheometer, while the yield stress determined by the truck measurement correlates with the slump and the ICAR rheometer results. Suggestions are given on how to improve the mixing truck for use as a rheometer.
Proceedings Title: Proceedings| SCC2005
Conference Dates: October 30-November 3, 2005
Conference Location: Chicago, IL
Conference Title: 2nd American Conference on the Design and Use of Self-Consolidating Concrete and International RILEM Symposium on Self-Compacting Concrete
Pub Type: Conferences
concrete, concrete truck mixer, rheology