My dh is a construction worker, so my boys were able to visit the job sites and even sit on some of the equipment and "help" since they were very small. My oldest (18 years old) now works with dh on his breaks from college, but believe me, he has no intention of doing it for a living. So far dd, age 2, is not interested in construction, but I saved all the books just in case. She does love going for rides with Daddy in his pickup though!
BTW, they are CONCRETE MIXERS, not cement mixers. Concrete is cement and sand mixed together, which is what the mixers carry to pour foundations. Can you tell I have been married for 22 years to a construction worker?