Rissbreitenbegrenzung mit verzinkter Bewehrung

Crack limitation with zinc-coated reinforcement

The check of a sufficient crack width limitation is an essential part within the serviceability design of RC structural members. Examples from the recent past have shown that it often gets decisive for the overall reinforcement content in infrastructure projects like tunnels when the design provisions of EC2 are applied. Besides other criteria crack limitations are mainly used to increase the structures durability by protecting the applied reinforcement against corrosion. In case this corrosion protection is given by coating (galvanizing) the rebars with zinc, the corresponding requirements for allowable crack widths could be reduced from a technical point of view. However, excessive cracking has to be prevented in any case. The bond behavior of the reinforcement is the most important issue for keeping crack widths limited. In this regard, studies by other authors, e. g. [1], have identified deviations between regular and zinc-coated rebars, without deriving a quantitative ratio for the different bonding types and bar diameters. Thus, comparative experimental investigations on the bond behavior and the crack limiting effect of zinc-coated to regular reinforcements have been conducted by the authors. Theoretical approaches are derived to describe the different bond behaviors and their effects on the crack width limitation.