From a Xypex Crystalline standpoint it does not matter how uneven the concrete is. The surface must be clean, have not coatings or other covering on it and must have an open pored sandy type of texture. If the surface is rougher than this it is still fine, an open pored texture is really the minimum. Clearly if the surface is of an exposed aggregate nature it will be “open pored”. It must then be saturated surface dry.
There are a number of videos on you tube that will show you how to install Xypex coatings. Some will show a close up of the concrete surface.
I trust that this answers your questions on this issue. If not please call and we can discuss.
Posted on 20 Nov 2015