Apply a layer mask to the concrete layer and use the cloud filter in it. Since the cloud filter produces a grey scale pattern, it lets us see through the concrete layer. To make things clear and interesting, keeping the layer mask selected, go to image > Adjustments > Threshold and adjust the settings till the time you get a good chipped off concrete look. Once you have got the basic look, use burn on the concrete layer to create, grime marks around the chipped areas. Also, use layers, paint with black and use smudge ti create water stains and more dirt and grime.
