When we remodeled our pool the company use Decoseal. It comes in a large caulk tube. They used backer rod, a foam like tubing to fill most of the space. Then the decoseal. The decoseal self levels, they then pushed fine sand on top of the decoseal so that the finish is like sand. Looks real good actually. The decoseal comes in different colors. You will se it very often in comercial concrete jobs. Next time your at a convience store look at the concrete the grey caulk in between the concrete joints is decoseal.