Photocatalytic Concrete Admixture?

I am looking for expert advice with regard to the use of photocatalytic concrete and the admixture TiO2. I have never used this material, my design/build team has never used it, and most tilt-up subs that we speak with laugh when we ask about it. My client is interested in it because of the "self-cleaning" qualities and the low maintenance aspect of it. Also, I am trying to figure out if it is supposed to be sealed somehow? This is for a commercial office building, so obviously we do not want to allow any moisture within the wall cavity. Also, IF we want to introduce color (paint) anywhere, can the material be painted? I realize that defeats the purpose, but it would be in small areas for design purposes only. Any help would be much appreciated! Thanks, Justin Rogers, AIA