Current State of Practice of Corrosion Protective Systems for Tierods and Tiebacks Used in Marine Applications-PDF

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The paper reviews corrosion-protection systems for steel tie-rods and tiebacks used in marine construction, where seawater and repeated wetting and drying can accelerate corrosion.

It describes four common approaches:

- <strong>Fusion-bonded epoxy (FBE):</strong> An economical coating, but damage can expose isolated areas to corrosion. It requires careful handling, inspection, and repair. ASTM A934 coating is more abrasion-resistant but less flexible than ASTM A775/AASHTO M284 coatings.
- <strong>Hot-dip galvanizing:</strong> A zinc coating protects steel sacrificially and can continue protecting small exposed areas. It is durable and less vulnerable to handling damage, though generally more expensive than epoxy coatings.
- <strong>Coal-tar epoxy (CTE):</strong> A relatively economical, abrasion-resistant coating applicable to a range of steel components. As with FBE, it must be inspected and repaired if damaged.
- <strong>Grout encapsulation:</strong> A plastic sheath and cement grout isolate the steel from water and air; the grout’s alkalinity also helps passivate the steel. Factory production supports quality control, but transport damage must be repaired, and field splices need equivalent protection.

The paper emphasizes that connections and end anchorages are particularly vulnerable because threaded steel is exposed and may contact water, air, and dissimilar metals. Protective caps, coatings, grout, grease, or tape can help safeguard these areas. Multiple systems may also be combined to provide layered protection.

No single system is best for every project. Selection should account for site conditions, environmental aggressiveness, handling and installation requirements, design life, inspection needs, and cost.

Keywords

corrosion protection

steel tie-rods

tiebacks

marine construction

fusion-bonded epoxy

hot-dip galvanizing

coal-tar epoxy

grout encapsulation

end anchorages

sacrificial zinc coating