Corrosion Protection
Coatings for Steel
& Concrete

How corrosion actually starts

Corrosion of steel is an electrochemical reaction. It needs four things at once: an anode where iron gives up electrons, a cathode, an electrolyte (water, condensation, salt fog, wet soil) and a metallic path connecting them. Take away any one and the reaction stops. Every corrosion protection strategy attacks one of those four.

Concrete corrodes differently. The concrete itself is attacked by acids (hydrogen sulfide converting to sulfuric acid in sewers and lift stations is the classic case), and the steel rebar inside corrodes once chlorides or carbonation break down the alkaline layer that normally protects it. Rust takes up several times the volume of the steel it came from, so corroding rebar cracks and spalls the concrete from the inside.

Anti-corrosion coating systems side by side

No single coating is best everywhere. The table compares the systems you will see on real bids.

Surface prep decides the result

Coating manufacturers will tell you surface preparation is responsible for most coating failures, and our field experience agrees. On steel, the cleaning standard and the anchor profile are specified together. On concrete, the target is sound, clean, dry concrete with an open texture. Full detail is in our surface preparation guide.

1. Degrease

   Solvent-clean oil, grease and cutting fluids before blasting so the blast does not drive them into the profile.

2. Blast to the spec

   Blast to the specified cleanliness, usually near-white for immersion, and check the anchor profile with replica tape or a depth gauge.

3. Check salts and dew point

   Test for soluble salts where chlorides are likely, and keep the steel at least 5°F above the dew point.

4. Prime the same shift

   Coat blasted steel before flash rust forms, typically the same day.

5. Stripe coat

   Brush edges, welds and fasteners before the full coat.

6. Inspect

   Measure dry film thickness, run holiday testing on linings, and pull-off test adhesion on a test area.

What corrosion protection costs, honestly

Installed cost is driven far more by access, surface prep and downtime than by the coating itself. Blasting, containment of blast media, scaffolding and confined-space entry can be most of the bill. A thicker, more durable system often costs less over the life of the asset because it pushes out the next shutdown.

• Prep-heavy jobs (old lead paint, heavy rust, confined tanks) cost the most per square foot regardless of coating.
• Fast-cure systems such as polyurea and polyaspartic can cut downtime from days to hours, which often matters more than material price.
• Get bids on the same spec: same prep standard, same total film thickness, same testing. Otherwise you are comparing different jobs.