Laitance is a major cause of failure in flooring installations. It takes the form of a weak, friable layer on the surface of concrete and sand cement screeds which appears after curing. It is made from cement and fine aggregates that rise to the surface when too much water is added. (Google)
...a site or use dedicated to "laitance" ...tips / information, that's what comes to mind. Not so excited, sad to say. My credit for it: It is a 1 word .com, in the building sector ...that is a little juicy. I suggest a range of mid hundreds (to the right buyer that relates to this, hope you get something)