What Causes Orange Stains on Concrete?

March 2, 2021

You’ve probably come across strange orange stains on concrete at some point, whether it’s on a sidewalk, driveway, parking lot or garage floor. These rusty-looking marks often look like meteors. But what causes them, and how do you deal with this issue?

There’s a common misconception that orange stains on concrete are from leaky cars. However, these are actually rust spots, and they come from inside the asphalt or concrete itself, not necessarily from other sources. Fortunately, there are ways to remove these rust stains from your concrete surfaces.

Certain types of asphalt and concrete aggregate contain pyrites, a type of mineral prominent in various river gravels. In some cases, there can be reactions that occur near the surface of the pavement if it’s exposed to moisture. As that part of the concrete oxidizes, the minerals build up and stain the asphalt, which can also cause that part of the concrete to swell up a bit, and potentially crack. If the area does not get treated after this chemical reaction, the rust spot will only worsen, and sink deeper into the concrete itself.

Depending on the number of pyrites in the concrete, there could be a large number of these spots that show up. If there’s a very large number of rust spots on the surface, there’s also a chance fertilizer could have spilled on the concrete, and the remnants created the orange spots on the ground. This is more likely to occur in areas where fertilizer is stored and used than out in general parking lots and sidewalks. Most of the time, those stains are indicative of the presence of pyrites.

Removing the stains

So now that you know what causes these orange stains (pyrites usually, and fertilizers sometimes), how do you go about removing them and preventing the problem from getting worse?

There are some methods available that are ideal for more severe problems, such as grinding or sandblasting, but note that those methods will eat away a part of the concrete. Most of the time, if you catch the problem relatively early, you’ll be able to get away with using a rust stain removing solution like Magica to get rid of orange stains on concrete.

Be sure to follow all the instructions that come on the Magica packaging. You’ll find it to be quite an easy product to use. Letting it sit and do its work for the appropriate amount of time is important so you can let it seep into the concrete and eat away at the rust that’s built up below the surface.

Once the Magica has finished doing its work and you’ve done any necessary scrubbing, you can rinse the area and let it dry off. If needed, you can apply the product again and repeat the steps listed on the manufacturer’s instructions.

Interested in learning more about how you can remove rust stains from concrete? We encourage you to contact Magica, Inc. today with any questions you have and we will be happy to provide you with further information about our Magica product line.

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