The following are photos where a patching material was used to level a floor. The material was placed from a feather edge to 1” in depth. After placement and curing they found some hollow sounding spots. The carpet was removed and the material was found to be debonded from the concrete substrate. The reason for the issue was inadequate floor preparation. The topping was solid and stayed together, but couldn’t bond due to the smooth, dirty floor. You can see on the loose pieces of material, the dirty substrate transferred to the repair material. After proper surface preparation was discussed, it was recommended the floor be cleaned and abraded before another patching material was placed. H2 was recommended as the repair material to use.