Collection: Corrosion Protection

Corrosion of steel reinforcement in reinforced concrete is usually not visible — until the rust reaches a critical amount and the concrete cracks from the inside. By then, the damage is more extensive than surface signs indicate. Corrosion protection of the reinforcement is a mandatory step before concrete repair — skipping it causes the entire repair to fail prematurely.

The mechanism of reinforcement corrosion in concrete

In healthy, alkaline concrete, a passive oxide layer forms on the surface of the reinforcement, protecting the steel from rusting. Both carbonation and chloride exposure reduce the alkalinity of the concrete — the passive layer breaks down, and the reinforcement enters active corrosion. The corrosion product (rust) occupies several times the volume of the original steel — this causes the concrete to crack from the inside.

What types of corrosion protection materials exist?

Rust converter: Chemically transforms active rust into a passive, stable phosphate. A preparatory step — it does not replace the passivation layer but stabilizes corrosion remaining after mechanical rust removal.

Passivation mortar (EN 1504-7): A cement-based repair mortar containing corrosion-inhibiting additives, applied directly to the exposed reinforcement. It restores the alkaline environment around the reinforcement and prevents further corrosion. According to EN 1504 standards, this is a mandatory step in any concrete repair where reinforcement is exposed.

Migration corrosion inhibitors: Materials that diffuse from the surface into the concrete, forming a molecular corrosion protection layer on the reinforcement — even where the reinforcement is not exposed. They can be used as preventive treatment and in early carbonation cases.

The order of corrosion protection in concrete repair

The concrete repair layering: (1) removal of damaged concrete and exposure of reinforcement, (2) rust removal and rust conversion, (3) application of passivation mortar, (4) repair mortar, (5) surface protective coating if necessary. Skipping step (3) endangers the durability of the entire system.

Browse our corrosion protection products or request advice to assemble a protection system suited to the condition of your reinforced concrete structure.