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  • Brian San Diego, CA
    Finally got my GC and a quality control person from the concrete supplier (they did not do the finishing work) to come out and inspect it. The contrete guy said he sees this 8-10 times a year and it is retained moisture, possibly due to finishing
  • Hudson Designs Loganville, GA
    Sound like a well thought out answer. And good cure to it as well. This is call acid etching, You could have used muriatic / hydrochloric acid as well but it more dangerous.
  • Wow, Another one of those Vinegar things you keep hearing. Did you take any pictures of the patio after you lost the stains?
  • Itsreally C Marietta, GA
    you're right - you'll just transfer the shading to a darker hue,,, that doesn't look like the normal difference in curing shades - i'd bet someone spilled something on it OR overloaded certain spots w/curing compound
  • Hard to say for sure without knowing what additives and curing agents or sealers were used when it was done. I am pretty confidant that in San Diego the problem was not frost, LOL but high heat and how they dealt with that is a possible factor.
  • have you spoken to the contractor who did this and if so, what is his response?
  • Great thread. I'll remember this....!
  • Hi Brian- we are having the same issues with our newly poured patio! It's been almost one month and still have grey blotches on one side of our patio. I think we should try the vinegar solution, but did you mix it with water first or pour directly onto
  • Brian San Diego, CA
    I had a non-colored concrete patio poured in November, and most of it dried a uniform light gray color, but there are some large dark gray splotches on it in some areas. The splotches are generally in the shadier areas, almost like those areas cured
  • Brian San Diego, CA
    These photos are part my existing project called "Concrete cured with dark blotches". My concrete cured with these dark areas (it is not wet, although it looks that way in the photos). Looking to discover how this happened, and what are my options for
  • Superior Pools El Cajon, CA
    Looking at the picture which I didn't see before, it looks like the mix is off. This does not look normal.
  • Looking at the photos, this is definitely something you will have to get the contractor who did the patio out to remedy. You should have a one year warranty on materials and workmanship. Without seeing it in person, it is hard to say what is the cause,
  • Hudson Designs Loganville, GA
    Looks like maybe rain got to the slab before it set and they topped the area that washed out maybe with Portland cement. Is that a leathery or wrinkled surface is see? There are different blends of Portland as well. Did you see them place it?
  • Brian San Diego, CA
    Another closeup of my mystery concrete problem
  • Brian San Diego, CA
    Just to wrap up: Turned out this was "retained moisture" caused by "hard troweling" where they trowled the surface a little too late, after it had already started to set up. This causes the top surface to "densify" which prevents all the moisture from