Optimization of rheological properties of self-consolidating concrete by means of numerical simulations, to avoid formwork filling problems in presence of reinforcement bars.

PDFTech ReportNUTC R344Project #00042528DTRT06-G-0014Self compacting concreteRheological propertiesReinforcing barsFormworkSimulationNumerical analysisFillers (Materials)MissouriMissouri University of Science and Technology. Center for Transportation Infrastructure and SafetyFeys, DimitriPark, JoontaekMissouri University of Science and Technology. Center for Transportation Infrastructure and SafetyUnited States. Dept. of Transportation. Research and Innovative Technology AdministrationUS Transportation CollectionThe influence of the rebar configuration on the occurrence of dead zones (= zero velocity) during flow of Self-Consolidating Concretein formworks has been investigated by single fluid numerical simulations. The main findings showed that for small inter-rebarspacing, the shear stress in the concrete cover becomes very low. The rebars act as virtual walls, concentrating the SCC flow betweenthem. Once the concrete cover is thus filled, the SCC remains stationary and can thus induce entrapment of air or a cold joint betweenthe stationary concrete in the cover and the moving concrete in the center of the formwork. The numerical simulations have revealedthat the SCC must be close to self-levelling to avoid the dead zones in case of a dense reinforcement grid. Increasing the spacingbetween the rebars and, to a minor extent, increasing the concrete cover allow for SCC with higher yield stresses, and thus lowerviscosities to be employed, while avoiding the occurrence of the dead zones