try placing a piece of bacon in a soda for 24 hours works faster than on the egg. also they use coke to clean battery cables on the car ever since i can remember. the military also use koolaid to clean with. want to try just put some lemon kool aid on your cement driveway where it is dirty and let sit for a short time rinse. we did that at boy scout camp in the dining hall that had a real bad stained cement floor cleaned it right up. they were amazed