It'not the cement exactly that will drain a battery, But what can happen is that if a charged battery is dirty or damp on the outside of the case a circuit can be completed from the negitive post down along the side and across them bottom and back up the other sideto the poitive post which will in time dicharge the battery, a cool concrete floor may cause this circuit to form more quickly due to the temperature differencial between the warm battery and the cool floor this can also happen in the vehicle if the battery tray bottom is replaced with a flat surface and not allow air to circulate around the battery keeping it dry, another reason for proper battery maintenance.
