W.R. Meadows Co. makes a product called Deck O Seal that will do the job of filling the gap between pool coping and cement deck.
cement is a bounding material geo polymar is the chemical composition
If the decking shifts,rises and moves it will push on the coping of the pool. Also, this helps keep water from under the pool and if the ground has moisture until it and freezes then it cause the deck to rise.
To set untreated timber in cement is asking trouble. Only pressure treated lumber should be used as a foundation support for outdoor decking. Greenwood can also lose its original shape.
Cement board
Cement board
Cement board
Cement with a rough textured finish or paver's. Paver's are probably a slightly better choice because if anything goes wrong with the plumbing you don't have to do any concrete cutting.
To allow floor flange bolts to have a place to fit and to anchor the flange to the cement /wood decking
Asbestos cement
cement is binding material while concreat is an homogeneous mixtur of cement sand and soil water etc.
That would depend on what type of pool you are installing and how you want it set up. Pool decking is most necessary for above ground pools, this would typically be of wood. For an in ground pool you would most likely use cement.
cement?