Replacing expansion joint caulking, found sand underneath. Keep it or remove?

[mcinlb]

It's time to replace the expansion joint caulking due to cracking. I started removing the old expension joint caulking/sealer material and discovered very fine sand underneath vs a backer rod.

Should I leave the sand and seal over it, or should the sand be removed and replaced with backer rod?

Thanks!

 

[ajw22]

Remove the sand. Sand does not compress and the purpose of the flexible material int he expansion joint is to not put pressure on the pool as the deck expands and the ground moves.