Hi - I wold be really grateful for some suggestions. Renovating an old garage conversion which seems to have been joined on to the existing house. When I removed the floor covering the underlying screed had started breaking up next to a wall thanks to an unused large copper pipe being buried in it. I thought I could remove the pipe and patch up the screed but it seems that there’s nothing under the screed and pipe! there seems to be patches of thin concrete at the edges. There’s a mix of sand and ?clinker in the hole. (I think this section was a path between the house and garage) It’s a 1950s house. I can see the dpc in the wall but there’s no dpm. Any suggestion? I was thinking compact the sand/clinker and concrete to floor level as the simplest quickest fix - or should I do something else?