The effects of coating thickness, deformation pattern, and bar size on the reduction in bond strength between reinforcing bars and concrete caused by epoxy coating are described. Tests included beam end and splice specimen testing. The results are compared with the splice tests that were used to establish the epoxy coated bar provisions in the 1989 ACI Building Code and 1989 AASHTO Bridge Specifications. Epoxy coating are found to reduce bond strength significantly, but the extent of the reduction is less than that used to select the development length modification factors in the ACI Building Code and AASHTO Bridge Sepcifications. Coating thickness has little effect on the amount of bond strength reduction for No. 6 bars and larger. However, the thicker the coating, the greater the reduction in bond strength for No. 5 bars. In general, the reduction in bond strength caused by an epoxy coating increases with bar size. The magnitude of the reduction depends on the deformation pattern; bars with relatively larger rib-bearing areas with respect to the bar cross section are affected less by the coating than bars with smaller bearing areas.

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  • Accession Number: 00607457
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 30 1991 12:00AM