Travertine pavers on Texas clay gumbo?
We are building a pool South of Houston and have selected some nice 6"X12"X1.5" travertine pavers for the ~900ft^2 of decking around the pool. We have gumbo clay (dirt) that does not drain well and is known for expanding/contracting. Our PB is wanting to put a concrete sub-deck down and then lay the pavers on top of the concrete. We are concerned that water will get trapped between the pavers and concrete. How would you recommend the decking be done? The way the plumbing was done, there is way less than 12" of clearance in some areas between the top of the deck surface and the plumbing so I do not know if the traditional method of using coarse compacted gravel and sand would work.
Any and all suggestions/comments are welcome, especially from people with travertine and gumbo soil experience.