Epoxy-Coated vs Galvanized Rebar: Which Corrosion Protection Wins

Reinforcement corrodes when chlorides (de-icing salt, seawater) or carbonation reach the steel and break down the passive layer concrete normally provides. The rust that forms expands, cracking and spalling the cover. In bridges, marine works, car parks and coastal buildings, that clock starts early — so specifiers reach for coated bar.

Fusion-bonded epoxy coating (FBEC, to ASTM A775 / A934) is a thin polymer barrier electrostatically applied to blast-cleaned bar. Pros: cheap per tonne, light, proven in North American bridge decks. Cons: the coating is only as good as its integrity — every nick, cut end or bar-chair abrasion is a corrosion initiation point, and site handling damages it easily. Bond to concrete is slightly reduced, so lap lengths increase.

Galvanizing (to ASTM A767 / EN ISO 1461) bonds a metallurgical zinc layer that protects two ways: as a barrier and sacrificially — zinc corrodes before steel, and small coating breaks self-heal electrochemically. Pros: robust to handling, cut ends still protected, tolerant of carbonation. Cons: higher cost, and in very high-chloride concrete the zinc is eventually consumed.

Rule of thumb: galvanized where handling is rough or breaks are inevitable (precast, marine, exposed); epoxy where budget dominates and site QA is tight (large bridge-deck pours). For the harshest exposure, stainless or GFRP bar out-lasts both. We supply B500B in bare, galvanized and coated forms — match the protection to the exposure class, not the habit.