The work you are describing is difficult, but that doesn't mean that it will translate to absolute strength or that it is the same as strength training. Moving 80 bags of cement won't translate to deadlifting 405 pounds a few days later unless the person doing that is already very strong. If the person doing that work does not overexert themselves they'll certainly be adapted to doing more of that type of work though.
Strength training is about making deliberate progression through repeated cycles of overloading and adaptation, and not about making equivalencies from one type of work to another. A bag of cement in the United States weighs 94 pounds. If you move 80 of them, you'll adapt to moving 80 bags of cement that weigh 94 pounds. That will not translate to the ability to lift four or five bags of cement at a time without deliberate effort. Will you empty the cement into a container adding a little more each time with appropriate recovery periods between until you can lift four bags worth of cement? Or will you move them one at a time, or maybe two at a time if you are able, to get the job done?