Anti-corrosion coating

When a ceiling or balcony is opened up and rusty bars show, covering them up again isn't enough. First the loose rust and crumbling concrete are removed, and then every exposed barRebar corrosionRust on the steel bars inside concrete. Rusting steel swells, cracks the concrete around it and makes it fall away in pieces, leaving the bars exposed. gets an anti-corrosion coating, usually with a brush, all the way round.

The coating stops rust from carrying on under the new material and helps the repair mortarRepair mortarA special cement-based mortar for rebuilding concrete that has cracked or fallen away, for example around rusty steel. It bonds well to old concrete and seals the reinforcement in. bond. There are various types and colours. In ceiling repairs you often see red or grey on the bars before they are covered.

On its own it isn't a fix: the repair lasts if the bars are well covered and the water that rusted them is stopped. If a bar has lost much of its thickness, an engineer needs to see it.