I have looked through other threads and can't find this specific problem.
I have a 1940's brick Tudor house w. a mostly-finished basement. I do not have water in the basement, however the concrete floor has spaces that are crumbly and small to medium pieces of concrete have come out with what I believe is efflorescence. Several of the rooms are carpeted and it feels like this is happening underneath. Of greater importance currently, are the rooms without carpet. Laundry, storage, 1 bedroom. These floors are painted and pieces are coming up. I tried patching with cement, and this just crumbles out eventually. The drains on the house do dump away from the foundation, and living in Denver, we do not get a lot of continues rain. We do have clay soil in much of the area. We are close to a lake, but are uphill from it.
Can I patch again with a different type of prep work? Any other suggestions would be appreciated.