Concrete stain flaking

[stangman39]

Hope everyone is having a good weekend.

I've had my shop slab down for about 2 years now.
A few weeks after it was poured I had concrete sealer/stain put down.
Nothing special, just something to add a coating and make it a little easier to clean.
One part of the slab closest to one of the bay doors continues to have issues where the paint/stain doesn't adhere well and bubbles up and flakes up and off.
This is the only area I have had issues. The concrete under this area seems to be a black color, almost like it never cured properly.

Pic attached.
Any thoughts or comments?
Is there something I can put down over this area and then repaint to prevent this from continuing to happen?

Thanks for the thoughts.

 

[Shea]

What was put down technically was not a stain. A concrete stain does exactly what it is called - it stains the concrete. Stained concrete cannot peel. As an example, think of an oil stain. Have you ever seen one peel?

What looks like was applied was a solid tint acrylic coating. These are generally are a very low solids water-based acrylic coating that penetrates into the concrete. The problem though is that they still peel just as a clear acrylic coat can. They are being sold by Behr and other large manufacturer's as a concrete stain. Here is an example. I don't know how they get away with calling it a stain.

The area you are having problems with may be too smooth for the coating to penetrate. Apply a few drop of water to it and see what it does. If it just sits there and doesn't penetrate within a minute or two, then you will need to rough it up first before applying more of the same product. You can do this by lightly grinding the surface. Sometimes 25 grit sandpaper will work for a small area like that when dealing with acrylics.