Advanced Blend Material to simulate paint on concrete. Both layers use the same bump map image in a Brazil Analytic Bump to ensure the 'paint' follows the contours of the underlying layer. Simply swap out the B&W dirtmap to achieve any pattern needed. Due to file size limits, I used smaller jpeg files than I would normally use, but these can be simply replaced by any image and matching bump map file of your choosing.
http://files.na.mcneel.com/rdk/materials/Paint on Concrete 2.rmtl