How to remove rust stains from concrete?

This is the most asked question was how to remove rust stains from concrete? When the iron starts to corrode then it forms rust and causes brownish strain. Rust stains on concrete are a very common problem and especially for those who use well water, as it is common for well water to contain high levels of the iron. If it is not removed properly then such stains are difficult to prevent.

The rust stains randomly dotted across porches, driveways, and other concrete surfaces. It is a simple task to remove rust stain from the concrete.

Most of the rust stains require acidic cleaner like oxalic acid etc to remove the rust stains and the acid helps in making it easy to scrub away rust stains. By converting it to an oxide that can be dissolved in water most acids remove the rust.

There are many methods used for the removal of rust stains from concrete such as applying hydrochloric acid, carbonated drinks, lemon, detergent, baking soda, etc.

Cause Of Rust Stains:

If you are noticing the rust stain on your concrete then the first step is to check the source of water because when water comes from underground wells, the iron content in that water can be very high. This iron water is the main cause of rust stains and it not only your concrete to stain, but it also causes the stain to surface it may be touching.

To prevent any damage to the surface use a concrete sealer and also use a crack filler to fill the cracks. You may also check all your water pipes for any leaks that may be affecting your concrete surface.

While laying the concrete the bars supporting the concrete should be non-corrosive. The metal begins to corrode causing the rust when water seeps through the concrete.

Methods Of Removing Rust Stains From Concrete:

Method 1:  Removing Minor stains:

Step 1: Wash Concrete with soap and water

Before beginning, wash the concrete with soap and water. Dirt and dust will get between your cleaner and stain this will make your work less effective. Before moving on let it dries for some time.

Step 2: Spray Lemon juice on the rusted surface

All rust remover has acids to scrub away the stain, pure lemon is the high concentration of citric acid which makes it a cleaning material. Apply the lemon juice and let it sit for 10 to 20 minutes and then scrub with a wire brush.

Step 3: For tougher stains spray vinegar on the rusted surface

Spray the vinegar and let it sit for several minutes and then scrub it with the wire brush then wash with cold water and repeat for the difficult stains.

Step 4: With brush scrub the surface of the concrete

After applying lemon juice or vinegar let it sit for some time and if it is a painted or smooth concrete scrub the surface with a stiff bristle brush.

Do not use metal bristles because it can remove the top paste layer in the cement and expose the aggregate material.

Step 5: Wash with cool water:

After washing with cold water let the concrete dry and goes after the stain again if needed.

Step 6: Use diluted vinegar and sponge to scrub

Without damaging the surface if you are not using a wire brush then use a sponge with warm water. First test the cleaning product on a small corner of concrete. Mix one cup of vinegar and one and a half cup of water and start scrubbing in circles, it will work overtime and may take 3 to 4 washes.

Method 2: Removing Major Rust Stains:

Step 1: Commercial Cleaner

If the vinegar and lemon juice are not working then move on to commercial cleaner. You will need to use heavy-duty cleaners, before applying any chemical wash the concrete and let it dry.

There are some safety precautions such as;

1. Work in a well-ventilated area.
2. Wear eye proctor and gloves.
3. To protect skin wear a long-sleeved shirt and pants.

Step 2: Use cleaner that contains Oxalic acid

Use the cleaner that contains oxalic acid like f9-BARC and these types of sprays are also used to scrub sinks without scrubbing. These sprays quickly lift up rust stains.

1. They come in liquid or in powder form.
2. On rusted surface spray the cleaner and if the cleaner is in powder form wet it with water.
3. Before continuing to allow the mixture to sit several times.

Step 3: Use Tri-sodium phosphate

With a gallon of hot water mix ½ cup of tri-sodium phosphate.

1. Wear gloves before handling tri-sodium phosphate.
2. Apply the mixture on the rusted surface.
3. Let the mixture sit for half an hour.

Step 4: Scrub surface with the stiff-bristled nylon brush

After the cleaner sets in the scrub, the surface with a stiff-bristled nylon brush and do not use the metal bristles for gentle stains because this can remove the top paste layer in the cement.

Use the stiff-bristled nylon brush and work in a circle to remove the stain and when it’s done take care to remove all of it because if it left on the concrete for a long time it causes discoloration.

Step 5: Hydraulic acid to remove stains

To remove stains carefully handle the hydraulic acid and hydraulic acid is the most effective way to remove the rust stains. You need to act quickly because this acid can tint your concrete blue if left for a long time.

Mix two cups of acid with one cup of water

1. Let the acid sit for 5 to 10 minutes.
2. Working quickly scrubs away the rust stain.
3. Wash the surface with water.
4. Repeat if needed.

Step 6: Pressure Washer

For hard or tough stains use a pressure washer. Just leave you acid on the stain for some time and then apply the pressure washer. To easily lift the stain from the surface it puts concreted force on the stain.

Method 3: Preventing Rust Stains

 1: Seal your concrete:

For the best protection against rust stains seal your concrete. Concrete sealer is applied like the stain on wood & soaks in concrete and protects it from stains.

1. Select a day with very little chance of rain.
2. Wash concrete & remove existing stains.
3. Roll sealant on concrete.
4. Before placing any furniture on it let the sealant sit for 48 hours.

2: Avoid placing metal bottomed Furniture:

1. To protect your concrete you can get felt, runners.
2. With a sealant to prevent rust, you can try coating your metal furniture.
3. To prevent the rust you have to seal your rusted furniture.
4. If the room is moist even interior concrete gets rusted.
5. Inspect your house for leaks.

Read Also:

1. Self Leveling concrete
2. Concrete texture and its types