The problem does not lie with expansion; as mentioned, shrinkage (or contraction) should be addressed. Assuming that the slab will sub-divide itself into two equal sections of 25' x 25', you might want to induce a crack at the mid point.
I submitted the following suggestion to the engineers...
If the house is already roughed in, the windows set and the doors hung; there are fewer options to consider. Jacking the 'low' walls verses lowering the 'high' walls: along one axis you're OK, along the other axis you are creating unacceptable problems regarding the windows and doors...
My previous comments were intended for existing concrete structures; thus my suggested 'remedial' solution. For people that are considering new concrete structures, the same crystalline technology can be 'batched' into fresh concrete. I have first hand knowledge of concrete improved by this...
The epoxy coatings could have been applied for asthetic reasons; realistically, they were probably meant to protect the seawall. As previously mentioned, the coatings (particularly, on just one side) are making matters worse. A remedial solution might be to completely remove the coatings and...