We would recommend 402 Damp Proof Coating for your application as this will provide a tough, durable finish as well as dealing with any damp in the substrate. If the concrete is a smooth, polished finish we would recommend the it is prepared with a diamond floor grinder to create a key or alternatively you could use an acid etch to prepare the surface, something like Rust-Oleum Mathys 108 Surfa Etch Solution but this would need to be thoroughly cleaned away with plenty of water before application of the paint system.