It would take a lot of urine to build up structures like this. It would seem a lot easier just to take urea up in bulk then relying on people peeing into a "community urine jug" to slowly build up the structure.
Better idea:
Don't send humans at all since they are so costly to maintain. Do everything with robots, which are 1000x cheaper and can do just about everything people can. With all the advanced electronics and sensors being developed, the robots would be equally successful at returning data and material from the moon than any manned mission. Keep the cost low, and use all those spared funds to deal with all the problems on the moon's neighbor, Mother Earth. There are a lot of problems on Earth, in case people haven't been paying attention.
Humans on the moon - been there, done that!