I had a drain leak in some 2-inch cast iron in a slab floor. The plumbers came out and jack hammered the floor out, did the repair and now I'm waiting for the inspector to come out and check the work. My part of this consists of putting dirt back in the hole and replacing the concrete, some carpet and tile. My question is should I just use some sand mix type of concrete and do I need to do any special prep before pouring the concrete.