Concrete Dark Spots

Often they are from the use of calcium chloride, but it could have been an inconsistent mixture or not enough water. I would contact the contractor who did the job first, rather than try anything yourself.

I would try power washing to see if it comes out which I think it will. It looks like a lot of dirt or could it be oil stains from a car?

Here's some insights for you

https://www.hometalk.com/diy/paint/exteriors/q-newly-poured-concrete-has-dark-spots-and-streaks-throughout-help-3288954

https://www.nevadareadymix.com/concrete-tips/discoloration/

Here are some reasons why there are dark splotches:

https://www.ehow.com/info_12197744_cement-dark-spots-drying.html

and what you can do about it:

Sealer needs to be applied in a uniform manner over multiple, light coats. You should allow two to three hours for drying in between each of your coats and watch for any blotchiness as the coats seal. When your last coat has dried and you don’t see any signs of concrete discoloration, you’ll know your job is done.

red: https://www.wrmeadows.com/blog/blotchy-concrete/

They should clear over time but if the mix wasn’t correct for the Temperature and humidity levels at the time of pour, there will always be slight discoloration.

Scrub in with a brush, some CLR, full strength, let sit and scrub some more, Rinse off. Good luck

here is more info to help you out

https://www.yourownarchitect.com/discolored-concrete-causes-and-what-to-do/#:~:text=One%20way%20to%20undo%20discoloration,an%20acidic%20solution%20might%20work.

https://www.patiocomfy.com/black-spots-patio-how-get-rid/

I am not sure if this is normal as these spots look really bad? If it has been 3 weeks, I would ask them how long till this returns to normal and what sort of warranty do you have on this?

Hi Dan, hope this helps you out,

https://www.yourownarchitect.com/discolored-concrete-causes-and-what-to-do/

Why Does My Cement Have Dark Spots in It As It Is Drying?

https://www.ehow.com/info_12197744_cement-dark-spots-drying.html

Concrete Discoloration – Dark Spots, Stripes, and Blotchy Concrete

https://www.foundationarmor.com/articles/discolored-concrete

Concrete needs to cure for at least 30 days. Looks like you had the perfect temp to pour, just give it another week to ten days. Lots of helpful solutions here as well.

Interesting finding. They do have tinted sealers if it does not disappear.

https://homeguides.sfgate.com/make-deck-stain-lighter-42765.html

Our concrete didn’t do that. Looks like mold me. But I and not expert eithet

This problem has come up in the past and the outcome was it will lighten but not go away. I would contact your contractor with your concerns.

If your contractor said that this is a normal part of curing, then I'd wait it out. If it is still like this come spring, then I'd be worried and could contact the contractor again!

You can use a primer for concrete

I would contact your contractor. This will not completely fade away, the color of all of it might fade, but the spots will still be there.

Hi Dan. I am worried that your batch of concrete wasn't mixed well enough. Call your contractor with your concerns. The squeaky wheel gets the oil.

Hi! I agree with the others that this is something you want to address first with whomever mixed and/or installed it. Stay safe!

You should contact the contractor because I don't think that is normal.

I spoke with the quality control person at the concrete company and he confirms there was 1 percent calcium chloride in the mix as well as fiber mesh added by the company not the contractor pouring the concrete. He said it just happens sometimes depending on the weather and for me to use equal parts water and vinegar to lighten the spots and to rinse off after 15 minutes. It is hard for me to believe that I have to treat 1600 sq ft of concrete spots with vinegar to make this look like normal concrete. I asked if there might have been a mixing issue and he of course said no but certainly if weather can cause this when calcium chloride is added then why ever add it. It seems like a huge risk. Thoughts on if I should start trying to treat the spots with vinegar or if I should make the companies involved give me some financial compensation or further research what happened to three truck loads of concrete? Was I truly this unlucky? Or was it a mix issue. Thank you so much for your advice!

We've had concrete poured for a patio in two different homes and this never happened. I would definitely call them back and discuss further. Also, if you can't get anywhere with them and the vinegar doesn't work you could try staining or painting the concrete. Not ideal, but perhaps it will cover the spots....although they might bleed through. We've done both with great results, but again, we didn't have those spots to deal with. So sorry this happened...

Just had mine done 3 days ago, these spots showed up 24 hours after it was done

Dan, can you give an update?

I haven’t priced the stain out yet