My question is, I’m not sure what the other material is, is there way to tell if it’s cement based or this calcium sulphate screed I keep reading about.
Ardex say it needs to come up, but the tech document online says it can just primed with p51, so it’s Doesn’t touch the new self-levelling compound as it will react with it.
I can scratch it with a chisel, and when I soak it in water it doesn’t seem to break down. Am I worrying about it too much and just should get on with the job.