Optimization of Rheological Properties of Self-Consolidating Concrete By Means Of Numerical Simulations, To Avoid Formwork Filling Problems in Presence of Reinforcement Bars

Disclaimer The contents of this report reflect the views of the author(s), who are responsible for the facts and the accuracy of information presented herein. This document is disseminated under the sponsorship of The influence of the rebar configuration on the occurrence of dead zones (= zero velocity) during flow of Self-Consolidating Concrete in formworks has been investigated by single fluid numerical simulations. The main findings showed that for small inter-rebar spacing, the shear stress in the concrete cover becomes very low. The rebars act as virtual walls, concentrating the SCC flow between them. Once the concrete cover is thus filled, the SCC remains stationary and can thus induce entrapment of air or a cold joint between the stationary concrete in the cover and the moving concrete in the center of the formwork. The numerical simulations have revealed that the SCC must be close to self-levelling to avoid the dead zones in case of a dense reinforcement grid. Increasing the spacing between the rebars and, to a minor extent, increasing the concrete cover allow for SCC with higher yield stresses, and thus lower viscosities to be employed, while avoiding the occurrence of the dead zones.