Help, I have a concrete floor in the basement about 300 square ft. floore has black mastic or tar which I am srcaping off as much as possible. Concrete floor is not in good shape it has some bomps and crack lines, can I do a mud job over about 1" tick, can you please advice the procedure of this project, any advice is very apreciated.
Thank you Enzo Degregorio

Enzo,

A mud job is exactly what you need. I recommend you make it a bit thicker than an inch if at all possible. The deck mud can be either bonded to the old or allowed to float with the placement of a slip-sheet. Since your slab is cracked, I suggest the slip sheet method.

Place plastic or tarpaper on the floor. Mix your mud. 5:1 sand/Portland. Add just enough water to make a very dry mix, like sand castles on the beach. Screed it flat, then compact it with a wooden float, then screed again. Finally steel trowel to compact the surface.

300 ft. will require one yard of sand at just over 1 inch thick, and 6 bags of Portland.

Ciao, Jaz