I have removed a 3'x 5'x (1" to 3") volume from a 8" thk. concrete wall. Water had gotten in the wall and froze causing the original concrete to pulverize. What would be the best approach to filling that volume (the wall is vertical)so the new fill material adheres to the original. The original surface is fairly rough. I plan to put a finishing coat of something over the entire wall after I fill the opening. Yes, the water leak is repaired.