Design of concrete structures using fusion-bonded epoxy-coated reinforcement

The Paper reviews structural aspects of fusion-bonded epoxy-coated reinforcement (FBECR) which may differ from that of non-coated reinforcement, proposes guidelines for structural design using FBECR in respect of those differences, and presents a rationale for these proposals. The study shows that coating of reinforcement to BS 7295 will not adversely affect mechanical properties, fatigue endurance or bendability of reinforcement. Bond behaviour is affected, however. A review of data demonstrates that anchorage and lap strength of reinforcement is reduced by an FBE coating where concrete cover is less than three times bar diameter. Even where cover is large enough to prevent splitting failures, loss of bond strength may occur with some rib geometries. Rib geometry is a significant factor in the anchorage bond behaviour of FBECR. Coated reinforcement is also found to be less effective in control of crack widths. Design and detailing requirements of various national codes or guidelines are reviewed. The Paper concludes with proposals for design detailing with FBECR, and for changes to methods for bond testing; and it identifies areas in which further data are required. The main proposals may be summarized as: (a) design bond strength for fusion-bonded epoxy-coated bars to be reduced by 20% relative to those for type 2 deformed bars in certain circumstances; (b) coated bars to be treated as plain round bars for crack control purposes. Conclusions from the study raise questions about the value of the BS 4449 test specification when applied to coated bond reinforcement.