You may need an exterior drain installed on the uphill side of the house to channel away groundwater. You may also want to look into some of the engineered, interlocking floor panels. These have a plastic dome arrangement on the underside to allow air movement, and ply on top to attach your finished flooring. Unfortuneately, it does raise the floor level more than a little, which can be a pain for thresholds to outside or stairways. Also, if you don't have a sump and pump, that may lower the hydrostatic pressure and prevent it from migrating up through the slab. There is little you can do from the top of the slab to prevent water intrusion...that pressure will delaminate most anything you apply over time. I'd seek assistance from some local specialists...I'm definately not one of them!