I am trying to finish my basement and did a lot of prep-work before putting up the insulation to the concrete wall. I plan to use XPS (extruded polystyrene) and then frame in front of it.
In inspecting the wall, I noticed an area of the wall that was discolored and had about 2 feet of crack. I started tapping on it and picking the crack with a chisel. It started to crumble. So, I decided to patch it with hydraulic cement patch. Well, that was 2 weeks ago.
Last night, I started to work on other things and notice the hydraulic cement patch is covered by white powder (see attached picture). I think it is efflorescence.
I am confused on how the efflorescence could appear on the patch only, but not on the surrounding existing concrete, or on other parts of the basement.
Do you think I have a big problem?
Since I will cover the wall with XPS (extruded polystyrene) panels, do you think I should worry about it?