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We're building a house that has poured-in-place concrete walls. I like the look of concrete, and we were planning on leaving some areas naked, both inside and outside the house, with some added stain in some places.

But I just saw the walls for the first time (a couple of weeks after the forms were removed), and they have some very dark ugly blotches on them. Here's a picture, showing a purple stained area (below) and a naked area (above).

enter image description here

I was expecting some color variation, but not this. The dark areas are almost black, or even a dark green color in some places.

Questions:
(1) Are these dark areas likely to fade as the concrete dries?
(2) If they don't, is there some way to treat them (short of using an opaque paint or covering/coating of some sort)

One ray of hope ... I saw a wall immediately after the forms were removed, and it was almost entirely black, but it was lighter when we came back the following day.

  • 2
    If it's only been a couple weeks you'll have to wait longer. Concrete hardens quickly but continues to cure for a long time. The majority of the curing reaction is complete in 30 days, but the process continues for a year or more. – Tyson Jul 9 '17 at 14:00
  • So, color changes should be expected during "curing" ?? – bubba Jul 11 '17 at 0:27

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