How to Remove Rust Stains From Concrete
Learn how to clean rust off your concrete slab, driveway, or walkway.
Driveways, walkways, and concrete slabs are commonly installed around the home to help support a garage or shed, provide a place for vehicles to park, or give you and your guests a clear path to and from the home. However, concrete can become stained by rust from various sources, and the unsightly stains stick out, reducing the curb appeal and aesthetic appeal of the home. Common causes of rust-stained concrete include metal-bottomed furniture, corroding bar supports in the concrete, leaks from rusted and worn gutter systems, or even rust in the water for those who have a well system.
While rust-stained concrete won't impact the efficacy of the driveway, walkway, or concrete slab, it does give the concrete a worn, dirty appearance that stands out next to rust-free concrete. Take the following steps to remove rust stains from your concrete.
What You'll Need
Equipment / Tools
- Nylon-bristle scrub brush
- Pressure washer
- Dish soap
- Lemon juice
- White vinegar
- Rust remover
- Trisodium phosphate (TSP)
- Hydrochloric acid
Wash the Concrete
In order to get the best results, it's necessary to rinse and wash the concrete to remove any dust, dirt, or other debris that could create a barrier between the rust-stain removal solution and the rust-stained concrete. Mix dish soap and warm water in a bucket, then wash the concrete with a sponge or scrub brush. Use a hose or pressure washer to rinse the concrete after washing, then let the concrete dry before proceeding.
Apply Rust-Stain Removal Solution
When the concrete is clean and dry, you can apply the rust-stain removal solution. Choose an appropriate rust remover based on the severity of the stain.
- Lemon juice is an effective option for dealing with minor stains. It needs to be poured on the rust-stained concrete and allowed to sit for about 10 minutes before scrubbing the concrete.
- White vinegar is another option for minor stains, though it's more effective than lemon juice. Pour the vinegar on the affected concrete and allow it to sit for about 7 to 10 minutes before scrubbing. Rinse and repeat for moderately stubborn stains.
- Commercial rust-stain removers may be necessary for major stains. Follow the manufacturer's directions for application and make sure to work in a well-ventilated area with appropriate protection, including safety gloves and safety glasses.
- Tri-sodium phosphate (TSP) can be mixed with hot water to create a powerful rust-cleaning solution. Mix about 1/2 cup of TSP with 1/2 gallon of hot water. Make sure you are wearing gloves and safety glasses, then apply the mixture to the concrete. Allow it to sit for 15 to 20 minutes before scrubbing.
- Hydrochloric acid can be used in extreme cases. Mix 2 cups of acid with 1 cup of water then apply the solution to the stain for about 5 to 10 minutes. Make sure to scrub and rinse quickly, because hydrochloric acid can stain the concrete blue if it's left on for too long.
Scrub the Concrete
Give the rust-removal solution enough time to soak in and begin to work before starting to scrub the surface of the concrete with a stiff-bristled nylon brush. This type of brush will help to scrub the rust stain away without damaging the concrete. Avoid using a metal-bristled brush because they can remove the protective layer on the concrete and expose the aggregate below.
If you are working on a delicate or painted concrete surface, then you will want to opt for a sponge and warm water instead of a scrub brush. Just keep in mind that some rust-removal solutions will eat through paint as well as rust, so it's best to use a mild cleaner.
Rinse the Concrete
Many rust-stain removal solutions will do damage to the concrete if they are not rinsed away after cleaning. Use a hose or pressure washer to ensure the rust remover is thoroughly rinsed off of the concrete when you are done scrubbing. If the stain remains, you may want to reapply the stain removal solution or switch to a more effective stain remover.
Tips to Keep Your Concrete Clean Longer
After you have gone through the process of scrubbing your concrete until it's rust-free, it's unlikely that you will want to repeat the process any time soon. To help prevent rust from staining the concrete, it's recommended to either seal the concrete yourself or have a professional seal the concrete about every 2 to 3 years.
Another way to help protect your concrete is to invest in a runner, outdoor carpet, or mat to go under your metal-bottomed furniture. Additionally, you can have the gutter system inspected for leaks. However, if the concrete was installed with metal support bars that are susceptible to rusting, the stains may actually be coming from inside the concrete. Make sure to only use non-corroding bar supports when you are laying your concrete.