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How to Remove Rust from Concrete

How to Remove Rust from Concrete

The yellowish-reddish rust stains are one of the most displeasing things to get on a concrete surface. Luckily there are plenty of homemade, commercial, and acidic solutions to tackle these stains.

It is always best to start from the least aggressive method and move on up when approaching any stain. We recommend starting with plain old soapy water and scrubbing the stained area with a nylon brush.

For homemade remedies, we can use vinegar mixtures baking soda mixtures. We may opt for commercial rust removal options and specific acidic chemicals in the worst-case scenario for aggressive stains. Read the alternatives below and assess the best solution for your concrete rust issue.

 How to Remove Rust from Concrete

Follow the steps and alternatives stated below to get the rust off the concrete.

 Items Required

  • Nylon Brush, Scraper
  • Bucket, Spray Bottle
  • Clean Rags, Cloths
  • Garden Hose/Pressure Washer
  • Gloves, Masks, Eye protection
  • Mild Detergent/Soap
    A bucket of domestic cleaning products

Possible Method Specific Items Required

  • Vinegar
  • Lemon Juice
  • Baking soda
  • Hydrogen Peroxide
  • WD 40
  • Commercial Rust Remover
  • Oxalic Acid
  • Sodium Citrate
  • Glycerol
  • Hydrogen Peroxide
  • Muriatic Acid
  • Hydrochloric Acid
  • Sodium Hydrosulfite Crystals
  • Calcium carbonate or Diatomaceous earth

Alternatives & Procedures to Remove Rust from Concrete

Try the alternatives below serially and get the stains off. Be extra careful with a chemical solution. Please use recommended safety precautions and understand the repercussions before using these methods.

Apply White Vinegar-Lemon Juice Mixture

  • Rust stains are stubborn to get off. We recommend trying just a little bit of white vinegar or lemon juice individually on the stain for the initial effort. Please opt for a 1:1 ratio of white vinegar-lemon juice mixture for deeper stains.
  • Pour the solution on the stain directly and leave the solution to sit for roughly half an hour.
  • Use a Nylon bristled brush and start scrubbing the stained area.
  • Rinse the area with clear water and dry it off with a rag or let it air dry.
  • Repeat the process if necessary.

Pro Tip: You can also find prepackaged cleaning vinegar at local hardware stores. They work on rust stains effectively too.

Apply Commercial Rust Stain Removers

There are plenty of prepackaged commercial rust stain removers in the market. Follow manufacturing instructions while using these products. We recommend products with oxalic acid as this acid is the go-to component to remove rust stains.

Some popular brands are Singerman, CLR, American Hydro Systems, Evapo Rust, Force 5 Ship’n Shore, Goof off, Rust Aid, Krud Kutter, etc. Please make sure you rinse the area once the treatment is complete to remove any product residue.
commercial cleaning solutions

Apply Baking Soda-Detergent Mixture

Our goal is to create a homemade poultice.

  • Try a 1:1 ratio for mild detergent without bleach with baking soda. Add water and mix till a thick paste forms.
  • Take the paste and apply the poultice to the stained area. Leave in the paste for roughly an hour.
  • After an hour, use a nylon-bristled brush or scraper to scrape away the paste.
  • Rinse with clear water.
  • Repeat the process if necessary.
    baking soda
Alternative
  • Take powdered baking soda and sprinkle it over the stained area.
  • Use a bit of hydrogen peroxide and start scrubbing the stained area with a nylon-bristled brush.
  • Rinse after the stains begin to disappear.
  • Off the shelf, 3% hydrogen peroxide will get the job done.

Spray Wd 40 on Rust Stain

Wd 40 advertises as a multi-use product. The product is made for a rusted surface and is formulated to penetrate the surface. We recommend applying WD 40 and giving it some elbow grease with a nylon-bristled brush. Rinse after treatment is done with clear water.
wd 40

Use Trisodium Phosphate-Water Mixture

  • Trisodium Phosphate needs to be diluted properly to be used on concrete. Mix Trisodium phosphate with water at a dilution ratio of ½ cup per ½ gallon of water.
  • Apply the mixture to the stain and let the solution sit for about half an hour.
  • Scrub the area with a nylon-bristled brush and rinse the area with clear water.
  • Let the concrete dry completely.
  • Repeat the process as necessary.

Aggressive Methods to Remove Rust Stains

Please note chemical solutions harm concrete and should only be used if other alternatives fail.

Mild Rust Stains

  • Make a mixture of oxalic acid powder and water. The standard ratio of the mix is for every 0.45 KG of oxalic powder; you need to dilute it with 3.8 liters of water.
  • Take a Mop and apply the solution to the stained area. Let the solution soak for two to three hours and rinse with your garden hose or pressure washer.
  • We can also use an ammonified thioglycolic acid solution to replace oxalic acid. Repeat the process as necessary till the stain is removed.

Alternative

Hydrochloric Acid-Water/ Muriatic Acid -Water Mixture

  • Dilute the acid with water at a minimum ratio of 1:3. For muriatic acid, dilute the acid with water at a ratio of 1:10. Apply the solution to the stained area.
  • Let the mixture sit for about 10-15 minutes and start scurrying with a nylon-bristled brush. Rinse with water after treatment or Pressure wash it. Let the area dry.
  •  Remember, if there are grass plants on the side of the driveway or patio, they will die upon contact. Be extra careful.

Deep or Stubborn Rust Stains

Follow the procedures below for stubborn stains.deep rust stain on concrete

Chemical Poultice
  • Make a poultice out of sodium citrate, water, and glycerol. Please ensure that the glycerol used is lime-free. 
  • The mixture ratio is for every part of sodium citrate; mix six-part worth of warm water and seven-part glycerol. Use Calcium carbonate or diatomaceous earth used for polishing.
  • An alternative to sodium citrate is ammonium citrate, but please understand that these are strong materials. 
  • Please note that we will most likely etch the concrete surface once treated with these chemicals. Ammonium Citrate will be a faster alternative.
  • Start mixing these ingredients till you form a thick paste and apply it to the stained area. Leave the paste for two to three days.
  • Scrape the paste and brush the area. Once the stain is gone, rinse the area with clear water.
Chemical Solution + Poultice
  • Take a bandage or an absorbent rag and saturate it with a mixture of either ammonium citrate or sodium citrate with lukewarm water. The mixture ratio is 1:6.
  • Apply the solution on the stained area with the bandage or rag and leave it in for 30 to 45 minutes.
  • We can also add sodium hydrosulfite crystals mixed in with water for an extra kick. Cover the layer with a poultice made from inert materials and water. Leave in the poultice for 45 minutes or an hour.
  • Scrub and brush away all the poultice or reside from the concrete surface. Rinse thoroughly with a garden hose or pressure washer. Apply another application of the sodium citrate-water mixture on the stained area to prevent the stain from coming back.

Did the Stain Turn Black After the Above-stated Removal Methods?

Some stains, when reacted with the sodium hydrosulfite, turn black. This phenomenon can also happen if the poultice is left on for too long. Treat the black-stained area with hydrogen peroxide if this has happened to you. Continue the removal process after that.

Please note: Never opt for these methods if you do not have proper respirator masks. Sodium Hydrosulfite releases toxic gases when in contact with moisture.

Possible Aggressive Mechanical Methods (Professional Help Recommended)

Dry Abrasive Blasting

This process involves shooting abrasive grits on the concrete surface to remove dirt, debris, paints, stains. Please note that sandblasting will make the surface texture rougher than before.

Full body protective gear is compulsory while using this method or even standing in the blasting area. The grits often rebound all over the place. If you accidentally inhale silica dust, it will cause lung damage. Recoating the concrete surface will be needed after sandblasting is complete.sandblasting-concrete

Water Blasting

This process is like dry abrasive blasting. We add water and send a pressurized stream of water and abrasive grit on the concrete surface. The same precautions apply as dry abrasive blasting. The dust released will be reduced when water is introduced, but we still will have to rinse the area after the operation is complete. Any abrasive grit shooting on the concrete surface will remove layers of concrete, so recoating will be needed.

Concrete Sanding/ Grinding

This process is the last resort method. You can get the handheld grinder or sander for concretes and sand the area away if nothing works. 

We recommend sanding the whole area to maintain uniformity. You will also have to re-seal the concrete floors.

How to Protect Concrete from Rust in the Future

  • Always apply sealers on concrete to create a protective layer on the top of the concrete.
  • If possible, avoid placing metal bottom furniture on the concrete directly. There are plenty of felt protectors mats to use for indoor surfaces.
  • Sometimes rebars embedded on slabs when exposed start rusting. We recommend using non-corroding bars during construction. If you see any exposed surfaces, we recommend sealing them up with concrete patchers or Fillers.

Related Questions

Is Pressure Washing enough to remove rust stains

It is highly unlikely that just pressure washing will be enough to take deep rust stains off. We recommend combining pressure washing with a commercial cleaning product for maximum results.worker cleaning floor with air high pressure machine