Textured Epoxy-Coated Rebars: Physical, Structural, and Empirical Characterization

Abstract

Although the traditional epoxy coating represents an effective corrosion protection system, it has the disadvantage of making bridge decks more susceptible to cracking. This phenomenon occurs because its smooth surface reduces the bond with the concrete and, therefore, increases the radial components of the force-transferring mechanism. To try to mitigate these problems, the Illinois Department of Transportation developed the textured epoxy-coated (TEC) reinforcement, which possesses a roughened surface and, in recent years, has been the subject of study at the University of Illinois Urbana-Champaign, in the U.S. Particularly, this experimental program explores, complements, and compares the physical and bond-slip characteristics of the TEC rebars developed hitherto. From the physical characterization, different parameters are measured on the textured surfaces to obtain a numerical comparison of each roughness type. Also, determining the adhesion strength and thickness of the textured coating reveals that it provides similar corrosion protection to the traditional approach while keeping its integrity on the steel substrate. The bond-slip characterization, in turn, was done using pull-out tests and, by combining these results with the microstructure examination of TEC bars, it is found that the absence of texture voids is related to the degradation of the slip resistance. Furthermore, through a finite element model, the development length of the TEC reinforcement is estimated and compared with the values calculated according to current standards. Finally, given the complexity of obtaining the surface parameters of the coating, an empirical, weight-based approach is developed for the TEC bars as a rapid method for assessing their roughness.