Concrete is permeable. Based on the mix design and how it was placed, it could be almost impermeable, or it could be really permeable. Adding a synthetic fiber, air entrainment, a pozzolan like fly ash or silica fume, ground slag and a superplasticizer to the concrete mix would really help reduce the permeability. Placing an impervious cover such as polypropylene sheeting would be a way to keep water from migrating through, or there are coatings that could be added, similar to roofing tar, that helps as well. I would contact a local concrete contractor supply store to find out what kind of coatings are available in your area for your project.
Concrete is good.