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Erschienen in:
2020 | OriginalPaper | Buchkapitel
The Effect of Fiber Geometry and Concentration on the Flow Properties of UHPC
verfasst von : Florian Gerland, Maximilian Schleiting, Thomas Schomberg, Olaf Wünsch, Alexander Wetzel, Bernhard Middendorf
Erschienen in: Rheology and Processing of Construction Materials
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Abstract
The economic relevance of fiber-reinforced concrete has increased steadily throughout the years. Fiber reinforcement improves the mechanical properties of concrete structures, but at the same time has the disadvantage of worsening the workability of fresh concrete. In order to better understand the influence of the fibers on the fresh concrete properties, rheological measurements were carried out on suspensions with fibers of typical rod-shape and atypical ring-shape with volume fractions up to 3.3% and 4.8% respectively. The study is carried out on UHPC as a matrix fluid as well as on a silicone oil as a substitute fluid with comparable flow properties. Investigation on a substitute fluid has the advantage of excluding interferences caused by thixotropy and interaction with granular components.
The measurements were carried out with ball probe systems and evaluated with a numerical simulation-based procedure in such a way that objective physical Bingham material parameters could be determined. It was found that due to the weak interaction of the fibers, the increase in viscosity with the fiber volume fraction is linear and independent of the fiber geometry. For the same reason, no significant yield stress has been detected.