Rust stains on concrete exteriors can make your building look unsightly. Those stains can come from a number of places, including water dripping on the concrete or metal tools or other materials left on the concrete. Rust can also occur simply based on the materials used in the concrete.

For the exterior building walls, rust can occur when rainwater drips down the side of the building or when metal elements on the exterior rust over time. Rust stains can also occur if the reinforcing bars used in the concrete construction are placed too close to the surface of the concrete or aren’t properly treated to prevent rust.

The good news is that most rust stains can be removed, and they can also be prevented with the right approach.

Removing rust stains

If you have existing rust stains on the concrete exterior, whether the sidewalk or the building itself, there are several rust removal products available. Start by cleaning any dirt from the surface to be cleaned. Then mix a powder rust remover product per package directions and apply the past generously to the rust stains. Wait the designated time and then rinse with water. Repeat as needed to remove all of the stain.

Preventing rust stains

The best way to prevent rust stains is to seal the concrete with an appropriate sealant. For commercial applications on sidewalks or building walls, it’s best to consult a professional on what sealant to use to prevent rust stains. The proper sealant can not only prevent rust, but also make overall maintenance of your builder exterior easier by preventing other staining on the concrete.

Identifying the underlying problem

Most rust stains are simply cosmetic in nature, but some can signal bigger problems. If rust stains are common on the exterior of your building, it’s a good idea to consult a professional to help identify the source of the rust stains. If the staining has occurred because of rusting reinforcing bars (rebar) in your concrete walls, the rusting metal could impact the structural integrity of your building over time. If rust stains are occurring because of water from a sprinkler system, it may be possible to treat the water to help prevent rust stains over time.

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