Extruded Concrete Curb Efflorescence

xquercus

We recently purchased a property with what appears to be a mineral deposit near the concrete curbs. There is quite a bit. It's not just a light coating but actual buildup. Doing some reading, I think this is efflorescence caused by minerals left behind after water evaporation. The attached pictures show a small portion of the area affected.

From what I read, this is often caused by watering vegetation adjacent to concrete curb. The water in our area is as soft as it gets. I have to *add* minerals to our water for our fresh water aquarium just so the fish will stay healthy. We are in the Northwest with about 9 months of rain out of the year. Even then, rain water is soft so what minerals are being left behind. Minerals from the soil? Lime from the concrete?

Most importantly, how do I clean this up? The pictures here simply don't do justice to how widespread and ugly this is. I've read several web sites that recommend a 50/50 solution of vinegar and water. In total we are talking many pounds of this mineral deposit. I haven't tried it, but I doubt the vinegar water solution would work. It works OK on bathroom tile and aquariums but this is a thick layer. Even if it does, I think we are talking a substantial investment in vinegar!

Is this indeed mineral efflorescence? Any thoughts on how to clean up hundreds of linear feet of this stuff? Dilute sulfuric or hydrochloric acid? Would that harm the concrete or asphalt? A pick axe? A jack hammer? Black spray paint? There is lots of this stuff and it's really stuck on that asphalt.

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SecretSquirrel

Have you tried a regular high pressure washer to see if that had any affect at cleaning up the efflorescence?

The use of the acids that you mentioned will etch the concrete and perhaps exasterbate the problem. I'm thinking that the vinegar solution is more or less to neutralize the alkalinity of the concrete and efflorescence and to break apart the deposits much like you would do in a routine cleaning of a coffee maker. You can purchase quantities of white vinegar at a shopping club like Sams or Costco at a reasonable price. I would apply a 50/50 vinegar solution via a pump sprayer, let it set for a while then follow up with a pressure washing. If that is not effective then more aggresive methods will be necessary.

xquercus

When you first suggested a pressure washer I was a bit skeptical. I hadn't really examined the staining close enough.

Looked at it today though and I think you are right on. I suspect a pressure washer will take care of at least 2/3 of the issue. There are areas where, once it became wet in the recent rain, the material became like wet chalk.

Thanks for the suggestion. We'll give it a try!