I am nearing completion of a pool remodel and trying to decide whether to use a semi-self-leveling caulk to fill the expansion joint between the coping and pool deck or to just grout it. As background, my coping is 12" by 24" bluestone and my pool deck is irregular shaped marble wet-laid on a concrete slab. I believe the marble is original to the pool. The bluestone is new. The builder did not do a very good job of preserving the expansion joint when the marble was laid. However, during the demolition process, I chipped away any mortar and grout that was filling the expansion joint and added deck-o-foam to preserve the joint when I re-laid the marble. So my question is. . . is caulking the expansion joint really necessary or can i grout it? I prefer the look of grout and have seen several pools around town that were built by very reputable builders that have a grouted joint. i realize caulk allows for expansion and contraction so if the pool deck settles or heaves, it does not apply pressure to the pool and coping. But how much resistance is a half inch deep and half inch wide grouted joint really going to offer?