I've rubber lined my shower floor and poured 2" of concrete on the floor. Now I want to tile it. What type of adhesive and grout do I use to keep it water tight?

Modified thin set. Dry or premixed. Sanded grout.

I would not use premixed modified thin set (only dry, meaning you have to mix it yourself), and sanded grout is not the way to go with excess water.
The best way to do the grouting is with an epoxy grout, as they hold up to water very well and don't need to be sealed. Also try to keep your grout lines 3/16" or less.

Matt Seiling
LINK REMOVED

Hey Stroud,

You're in the home improvement business are you? You use pre-mixed thin set, (which for your info isn't thin set at all, but it's mastic) , and on a shower floor no less. OH BOY!

Roofman,

Something tells me you may not have prep'd this shower right. Sounds like you did not place a pre-slope under the membrane. So, that rubber membrane is flat on the floor right? The areas around the drain may even be higher that the rest? How will any moisture that gets through leave the system through the weeps holes in the drain? How high up the walls and over the curb is the membrane? How are you building the walls and curb? Just a few q's to help you prevent a de-do.

OH... sorry, just noticed the date of this thread. Still all info is valid, hopefully someone else will be saved from building a shower wrong.

Jaz