Assuming you are looking looking for a masonry paint, you could consider Rust-Oleum Mathys Murfill Waterproofing Coating, this is available in many RAL, NCS or BS colours and states it is 400% elastic.

If you are looking for an elastomeric floor paint you could consider Flag Heavy Duty Elastomeric Floor Coating (Anti-Slip), this is available in a range of colours including 2 grey options.