What Causes Rust Stains on Concrete Driveways?

Apr 13, 2021 | Concrete Driveway Tips, Concrete Tips, DIY Tips

We love owning our homes and the freedom that provides. But as much as we would like to believe that things won’t go wrong, they will. One that might be on that list right now is your rusting concrete.

When you understand why it’s happening, it’s easier to prevent rust stains in the future. There are a few reasons why you see rust on your concrete, and we’ll discuss why, how to get rid of them, and how to prevent them from coming back.

What Causes Rust Stains on Concrete?

You may know different surfaces stain easier than others. Smooth surfaces are less likely to stain, and porous surfaces are more susceptible, where porosity or the volume of voids in concrete makes it easier for stains to happen in the first place.

The ease with which a rust stain occurs is associated with porous concrete because it’s more permeable, allowing the flow of staining agents and resulting in unsightly stains. The worst thing about rust stains is they can show up one day for no apparent reason. But one thing is for sure, once you know they’re there, you want them gone.

Below is a list of the most common (and surprising) causes of rust stains on concrete.

  • The water in irrigation systems contains small amounts of iron that react with the surfaces it touches, creating rust stains. Sometimes the spray from these systems overflows onto driveways and sidewalks, causing unsightly blemishes of rust
  • Although not real rust stains, leaking battery acid from cars, landscaping equipment, and even golf carts cause stains, too
  • We’ve all seen metal decorations in yards and on patios and driveways. Surprisingly, they rust and leave stains behind when they’re moved to another location Sometimes, depending on the makeup of the concrete, there might be elements of soft rock mixed in with a normal amount of hard rock, which makes up the majority of concrete. During the rock mixing phase, soft rock such as iron rock also gets mixed in with the others. Iron rock can literally pop out of the concrete because of its ability to absorb more water. When it’s close to the surface and exposed, oxidation or rust occurs
  • Maybe you’ve seen buildings with a red-colored apron at their base and immediately surmised that it was iron or the red clay around the foundation. Red clay is that color because of its high iron content, which eventually leaks from the foundation and stains surrounding surfaces
  • Fertilizer granules that end up on your concrete will seep iron and create stains. In a worst-case scenario, minerals from the fertilizer get into the concrete and cause permanent stains

How to Prevent Rust Stains on Your Driveway?

Prevention is worth a pound of cure, and that sure applies to rust stains on your driveway. Removing the source of the stains is the place to start preventing future ones. Be sure to remove all metal objects like furniture and decorations. The last thing you want to happen is more stains that only get worse.

After removing any likely sources of rust stains, you’ll have to clean your concrete well and prepare it for a quality concrete sealer. A good seal on your concrete ensures that it looks good for years to come and won’t disappoint you with unsightly stains.

A quality epoxy concrete sealer adds years of useful life and appearance to your driveway. It also resists stains, especially rust, and it won’t absorb moisture which contributes to more problems later.

How to Remove and Clean Rust Stains on Your Driveway?

There’s always some kind of maintenance task waiting to be done, and cleaning and removing rust from your driveway isn’t the most pleasant, but it is very important. Lots of people look for the best solutions for eliminating rust. Here are a few tips that work well.

  • White vinegar not only helps unclog drains and removing black mold, but it’s also very useful for removing rust. The vinegar reacts with the rust and causes it to liquefy making cleanup easy with a rag or paper towel. The trick is to allow the vinegar to soak the rust for about twenty minutes
  • Lime and salt are effective because of their acidity. Cover the rust with salt and squeeze lime juice over the salt, saturating it, and let the solution sit for 3 or 4 hours. The rust should then scrub away (Tip: a lemon works in place of limes)
  • Baking soda or sodium bicarbonate is a mild alkali that when mixed with water and worked into a paste, works well but not quite as effectively as white vinegar. You’ll have to work at scrubbing the rust away, but it works when others don’t