Few of things I can suggest:

1. If you use the girl in the render as reference, then the texture is way too large. I don't mean the blocks but the noise/distortion in the concrete is too large.

2. Some details you can add: Graffiti, oil/piss stains, moss/fungus growing around the seams, splotches of old paint, pasted flyers and old 'shadows' from flyers... You may also want to have some of the blocks sticking slightly outwards.

3. The normals of your wall mesh seem messed up, which is why you're getting that balloon like look. Make sure the normals of each face are hardened. I dunno how to do this in C4D though, sorry.