I lived in a house once that had wet linoleum floors on top of a slab in the summer. This was caused by the slab not having proper (or any) insulation under it. With no insulation under it (solid foam) the slab is cooled by the earth and the moist summer air condensed on it and it was nasty and slippery. If this is the case with you, then you are only seeing moisture in the summer. There isn't much you can do to remediate the actual cause, short of ripping up the slab, insulating and re-pouring slab, which is not practical. De-humidifying in the summer is your best bet, maybe even in addition to air conditioning. If you leave your windows open and dehumidifyer off on a hot, humid day then you will have sweaty floors.