Someone over at Bolter and Chainsword asked how I do my bases. Here's a shot of one without a mini glued onto it.
I picked up a textured sheet of plasticard from a local train/hobby shop. Cut it to shape and beveled the sides to have the same slope as the base. I used GF9 hobby scenics for the larger chunks of concrete with sand added in general places.
The tile is based with Astronomicon Grey with a Skull White drybrush. This is followed by a heavy inking using a 2/3 to 1/3 mix of Gryphonne Sepia and Devlan Mud. The rubble and sand is a base of Adeptus Battlegrey and a drybrush of Astronomicon Grey.
When working with this kind of base I find it easier to finish them then glue a basecoated mini on.