It really depends. Usually, when laid on the ground, concrete floors rest on
a waterproof membrane, that should prevent moisture from filtering through. I
would suggest to do three things: 1) measure the level of humidity in the
room; 2) ask an engineer to inspect the site e possibly check the
construction drawings; 3) if you are placing books on shelves, make sure that
the bottom shelf is raised a few inches off the floor.
Paolo Polledri