A friend did some drainage work in his basement and needed to fill in the channels he had cut in the concrete slab. The only two options were a concrete pumping truck (expensive) or mixing by hand. He decided to mix by hand using a Rapid Mixer. The project went smoothly with two people and it took almost exactly 90 minutes to mix, pour, and trowel 35 bags (6 of which were 80 pounds) with a single mixer. The mixer definitely showed some signs of wear after the task was complete but apart from a small puncture (from a piece of rebar), it was still fully functional and mixed 10 more bags the next day.
The video below is a time-lapse of the first hour of work.