Discolored concrete


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Old 09-18-22, 01:32 PM
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Discolored concrete

A few days ago I noticed the concrete starting to have a different darker shade to it. As you see in the photo.

I watered it down and let it dry. But today Iím seeing these white blotches as well

Does anyone know what that is and how to cure it?

I have about 40 of these concrete steps and itís just occurring at this section. We have a saltwater pool. could it be that? If so, why I would just happen there and not anywhere else?



Hoping someone can tell me whatís going on and how to fix it. I donít want to experiment with the wrong cleaning agent before I run it by some experts in the field.

thanks!
 
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Old 09-18-22, 01:41 PM
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That is efflorescence. Water containing minerals/salts soaks up into the concrete. The water evaporates away and the minerals are left behind forming a white deposit. Light pressure washing or scrubbing with a mild acid solution (CLR, vinegar...) can remove most of it but it will return.
 
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Old 09-19-22, 11:23 AM
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Thanks. I'll try both and see what works. And then look to sealing the concrete...

But what about the darker area? what type of stain is that?
 
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Old 09-19-22, 02:02 PM
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It's not stain. When you see darkened concrete and efflorescence the darkness is often caused by moisture but how the concrete was finished can affect it as well. Sealers don't really help since it's often moisture wicking up from below.
 
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Old 09-19-22, 06:20 PM
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oh boy, well, the efflorescence is only on these 2 steps. And the darker areas on these 2 as well as 1 other step. I need to do something to stop the moisture from coming up. I have a concrete driveway, and nothing like this has ever happened.
 
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Old 09-20-22, 04:54 AM
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Concrete can vary a lot depending on how it is finished. Just for fun go watch your driveway when it starts to rain. You may notice interesting patterns develop as it gets wet. You probably will be able to see various patterns that reflect how the concrete was finished.
 
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Old 10-26-22, 06:02 PM
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Well, it's me again. The white stuff has gone away, but the darkness is still there on the edges. Any other ideas on how to remove it? if it's moisture, could I use a heat lamp or something to evaporate it?

Plus I've had more puddles of salt water, sit overnight on other concrete steps, and now the darkness is there too. (why didn't I seal it!??!) I don't think this is moisture from the inside as it was obvious, it's where the water was.

I've read about a mixture of vinegar and water. Any thoughts on that working as well on the dark area? I'm going to try it on a small area just to see what happens. And is it better to do this cleaning in the sunlight or after dark?
 
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Old 10-27-22, 04:41 AM
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If the color of concrete bothers you so much maybe you should consider redoing things so you don't have plain concrete. Maybe go with a stamped concrete, brick pavers or some other non-concrete surface. I don't recommend pavers as they are concrete as well and darken when wet.

Concrete gets dark when it gets wet. That is just the nature of the material. Sealing almost never works long term as water will find it's way in from the sides or bottom.
 
 

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