Rust Stains on Cement Driveways

GA -- That works for me too. My old truck visits the Bonneville Salt flats once a year and after 10 years no matter how much I wash the bottom and coat it with Rustoleum our wet season causes it to drip rusty water.

The pressure washer (2200 psi version) concentrated stream does etch the top of the concrete a bit; but no one will ever notice that.

If your car has a big enough trunk to carry one just go rent it for a couple of hours. You don't need the "soap". Just hook it up to a garden hose.

Ed Weldon

Do you think it would work on tiles like this?

All part of a can of worms I opened.

Thanks, Ky.

Ky -- I kind of doubt pressure washing would would work on the tiles. The glaze on the surface of most tiles is too strong to be eroded by the pressure washer stream. Concrete is a lot softer, epecially if it is the lower test stuff (under 3000 pound) that most driveways are made of. The iron oxide gets into the tiniest microscopic cracks in the ceramic and there is no practical way to wash it out. The contaminated material has to be abraded off. I'd take a look at grinding and polishing the tiles with diamond abrasives. I suspect you may have to search a bit to find the contractor capability in your country for that job. But one never knows. Oz is home to a lot of very creative and industrious people.

A bit here about the chemistry involved: I learned this from dealing with dissolved iron oxide in well water. Iron oxide has 3 common forms: Fe3O4 is magnetite, very stable and is fairly rare in nature. FE2O3 the ferritic form. Common rust; it always has a color. It's the base state of the iron.

Another form has less oxygen. FEO. It is the ferrous form and can only exist in the absence of oxygen or a reducing environment. It is essentially colorless, is soluble in water and shows no color in water. As soon as the oxygen becomes available the ferrous ions grab it, shifting to the ferric form releasing some energy and gaining the typical rust color. A reducing chemical, sodium hydrosulphite, will strip oxygen atoms from the ferric oxide (FE2O3, rust)) molecule and convert it to ferrous oxide (FEO). At this point if you can physically remove the ferrous ions then you have accomplished an effective stain removal. That's how a product available in the USA, Iron-Out works in cleaning water softeners of iron build up on the resin.

But after an application of this stuff any ferrous ions that remain will oxidize as soon as the air gets to them. The stain returns if the surface does not facilitate a water rinsing. Any other chemical process in order to remove the stain must either remove the ferric or ferrous ions (as the case might be) or convert them to a stable colorless ion of some different form and lacks the objectionable color.

So you can mess with the various methods of rust removal, and there are many such; but you will be limited by what can be accomplished by chemistry, the means by which the offending ions can be removed physically from their hiding place or some method to convert them in a manner that prevents them from reoxidizing in the presence of oxygen (or other oxidizers like chlorine.) I have a feeling approaches to chemically rendering the iron colorless have been explored fairly thoroughly since it is a fairly universal problem.

Ed Weldon

Thank you. I'll report how it ended if it ever ends, Ky.

Sorry to hear that. Of course, yours is the only driveway in the entire subdivision with this problem and the HOA didn't offer any advice on how to remove the stains. Typical HOA autocratic actions.

You can try this stuff. I've never used it myself, and this is not an endorsement, but have heard it works. Concrete Rust Remover

If that didn't work, I'd get a gallon of flat latex, color matched to your driveway, and paint the rusted section.

Good luck.

Thanks, There are about 30 homes with Rust Stains and a half a dozen oil strains. Why only me?????

Solutions....sure, I have a few;

Egg the Homeowners Association's members houses

Set a bag of burning dog poop on the Homeowners Association's members front porches, ring the doorbell and run.

JUST KIDDING. Try muriatic acid. It may stain so be careful.

Hey when they do their walk around they usually piss a few people off. Now would be a good time to run for the office of President of the Home Association. If you get elected you most likely would have the votes to get it dissolved.

If someone does not like homeowners associations then why buy a home there?

If the power washing of the driveway doesn't work on removing the rust stains, you can apply a 2-part exterior grade epoxy floor paint to the concrete surface. Just make sure you apply silica sand to the surface when it's wet, otherwise it'll be very slippery.

Ohhh wait, forget the sand as you want the HOA inspectors to slip on it and break their collective arses! LOL Sorry, I just couldn't help myself!!!!

For the tile, there is Rust Remover that's sold in a hardware store. I know it works well for tile, clothes and rugs.

With the cement being pourous, not sure.

You never gave the size of the spots. If the area was small, a wire brush would work, but it creates a secondary problem. A bright spot. This will go away over time. I think that power washing the driveway may be the way to go, and it you have to, use a power wire brush (mounted on an angle grinder) to get the stubborn ones out. Power washing would return the cement to a more pristine state. I do know the bleach will brighten cement too like the old cement that looks somewhat orange.