Grout Question

[tuck]

I had a new fiberglass tub installed along with new cement board and shower tiles. The window was replaced with glass blocks. All the joints were grouted. The problem is the grout joints have opened up at the glass block to tile joint and at the plastic tub to tile joint. Should grout be used at these joints or is a sealant recommended. Thanks. Tuck

[HayZee518]

mix up a quality white grout and squeegie it in well. when it dries use a silicone sealer and apply with an artist's brush