I need to pour a 7'X10' (6"deep) concrete slab over an existing asphalt surface. I would rather not break up the asphalt, but pour on top of it. Is it ok to secure the slab in place prior to pouring by drilling and inserting 4" vertical re-bar spikes into the asphalt and then pouring over the 4" wire mesh and vertical re-bar spikes? Any suggestions greatly appreciated