Decades ago, doing commercial swimming poll rehabs, the designs always called for the pool deck expansion joints to be caulked. The expansion joint material was ripped an inch, then pinned back together with finish nails. After the concrete was poured, we'd peel off the rip, pack the joint with foam backer rod, and caulk away. The design ALWAYS called for the use of the caulking "system's" primer, and self-leveling caulk. Sikaflex was a popular brand with the project engineers. Usually two-part mixed in it's bucket.
Of course, pool decks are always pitched so water runs away. Well so did the self-leveling caulk. Eventually, we began using "vertical grade", "non-sag" caulk material. Paint the primer, stuff the foam rope, masking tape the joint, and putty knife in the caulk. It worked, albeit tediously. Eventually the supervising engineers wanted the joint "tooled" to be more concave. Some Dollar Store kitchen spoons were the perfect shape and size. I must have put down hundreds of gallons of that stuff. I have not been back to any of those places in years, so i couldn't speak to it's durability, but it sure did look pretty when it was new.
