Get a siloxane based sealer..we use we use it on huge bridge decks, pier caps, fascias of structures..
Its nasty stuff...high VOC, but of all the commercially available masonry sealers its the shizzle...
Yes like all sealers,it does need to be re-applied...but municipalities NEVER do this..however you being a diligent homeowner you'll care more about your property than a town or city...
Siloxane sealer
Foundation armor