waterproof cement floor

Our carport was enclosed to become an entertainment room. We carpeted it (with padding), to discover that the cement floor absorbs water from the earth below and it results in soaked carpet and padding. The padding acts like a sponge. We know we need to waterproof the cement floor, but a paint-type product like latex Drylock is not heavy duty enough. There is a product that is skimmed/troweled onto the floor to waterproof it, but we do not know the manufacturer or product name. Anyone know what this is or any other ideas?