I am in the process of replacing the side entry door on my garage. In the process of removing the door and cleaning the rotted sill, a large chunk of concrete came up. To me it looks like that when the garage slab was poured first. Then later a concrete walkway was added. In setting the rebar for the walkway they drilled ~3 inches horizontally into the garage slab and set a rebar hole. Over time, seasonal heaving and maybe rusting has caused the area above this to pop the chunk loose (pyramidal shaped about 3" deep by 4" wide by 10" long at its maximum dimensions). I would like to know what is the best method for fixing it? Do I cut that nubbin of rebar off (it is set in the sidewalk, but not anchored to the garage), block it off with a board, and then pour in some patch? What patch do you recommend in cold climates?
