i am remodeling my bathroom and I need to know how to best deal with my concrete sub floor. so short story long. while I was tearing up the bathroom floor tile I caused some cracks to form in the concrete sub floor. at the point where the sub floor met the vanity a large piece of the concrete broke away leaving the rebar behind and exposing the flooring underneath. as for that material it seems that under the 1.25" of concrete there is a later of black plastic then cardboard then the plywood floor. I should note other then the cracks the floor is level.
the broken part of the slab is 28"x11" at it's widest point and 1.25" deep.
my question is what do I need to do to fix this. I went to Floor and Decor and one of the on staff contractors told me I needed to fix the hole with Quikrete 5000. is this ideal? is there another type of concrete I should be using.
also how should prep the area on The vanity where the vanity and concrete meet. there is a 1/8"ish gap between the slab and the wood of the vanity.
any help would be very