Water Infiltration

In my shed/garage, I have two strips of 5000x1100x12.5 rubber conveyor belt on the concrete floor. I had to roll it up today and found patches of water, wether caused by rain run off or condensation, I don't know. Is there any way of preventing this as the rubber belts are awkward to move:( (ie heavy to roll and I have to remove everything from the shed to roll them!)

Is there a plastic membrane under the concrete slap. It maybe coming up through the concrete. You could try painting under them with an epoxy paint.

Thanks Barry, I actually have some plastic sheeting that I could place between the concrete and the belts. Why didn't I think of that before????:)