What to do with 15 bags of readymix?

Last fall I bought all the materials for a tradesperson to beef up the foundation under part of my house and deck, which included 15 bags of readymix. Then he had the usual fit for such folks who work for me around here and quit. I've decided it's so they don't have to come back and fix their mistakes and there are soooo many! Examples include, dripping water heater pipes, sconces falling off the walls in only a few months, toilet water shut off installed so the handle is inaccessible, therefore, it can't be shut off....etc. Anyway, I covered the bags which are on pallets with plastic and plywood, but discovered two days ago that they are already hardened.

Any ideas of what to do with them? I thought to make rocks, but now that's out. :..( I hate waste!