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.

(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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