4 months ago I extended my driveway to make it wider by have a section 45x5 feet added. The slab was put in by a licensed contractor, they had a cement mixer truck come by and put the concrete in as the floated it etc. All looked well.

There was three slab sections 6x5 feet in the run that had large areas of very dark spots "pinto contrete" the color was a very dark grey to almost black. Contrator said it's still drying.

Well it's been 4 months and those area are not getting better. Contrator will not return my calls. So I search the internet find that the dark sections are called entraped moisture and they can be fixed with white vinegar and a broom then rinse with water. So I pick up some white vinegar, wet the contrete first, pour some vinegar on the spots and run the broom back forth a few times. I see the dark areas start to disappear, magic, I rinsed everything down with water. I read I may have to do a few applications to get the color to match.

So several hours later I look at the slab that is now completely dry and the former dark spots are now lighter than the rest of the slab I figured I should do the entire slab to even this out. One application helped but since it's been raining I have not been able to try again.

Is concrete really this hard to put down without issues like this? I mean I see miles and miles of concrete daily without issues like this

I spoke with a concrete repair contractor and he told me the vinegar was the right thing to do because of the trapped moisture, and he said the dark areas are now lighter than the surrounding slab because of different drying rates and they should even out in time???

Any suggestions?

thanks!!

 

I do not know about all of the vinegar nonsense or "trapped moisture", but the bottom line is that it is concrete. It is a structural building material, not a surface finish. Often expectations do not match results, and the solution is to address them before dirt is moved.

 

I understand your point an to a point I agree. I did address them prior to the dirt being moved. I was told the surface you not end up like this. Not sure what else I could have done?