What about brick tint dye,supposed to last 30 yrs but will need sealing with polyurethane for the traffic aspect https://www.google.co.uk/search?q=brick+tinting&espv=2&biw=1304&bih=707&tbm=isch&tbo=u&source=univ&sa=X&ved=0CCYQsARqFQoTCOCj2IfL9McCFcu4GgoddosPBQ