well it depends on how you did your tile.
using a waterproofing agent you lay down on the drywall backing/*misc surface*, you then use a waterproof mortar
usually tile is set down using a mortar, then one that mortar has dried, and tiles are in place, you fill in the grout grooves with grout. after the grout has dried, clean your tile/ tidy up your grout lines. then seal the grout with another layer of water proof grout sealer.
you can also use a special tile varnish to really layer on your tile to put a strong protective shimmer on it *used with the mexican tile*.
thats if your tiling something.
if your using a pure grout as you said. id still use a sealer, the sealer is meant to prevent the break down of grout from water. and usually has to be reapplied after several months. depending on how much you used, this may/may not be a good idea.