I had a similar concrete pump used to lay our patio and service area. The problem was we had TORRENTIAL rain during the pour. They should have aborted and rescheduled but they were paying for the pumper by the hour.
They were supposed to oxide the top layer (dark grey) but couldn't due to the heavy rain. The finish was rough due to the weather.
Disappointed until the contractor offered to grind and expose the aggregate in the whole slab
at no charge to us. The alternative was jack hammer it up and re-pour.
Two full days and several $400 grinding pad sets later and we now have smooth exposed agregate, almost like a polished concrete finish.
I paid him for his extra materials and everyone was happy.
But back to the point, these concrete pumps are fantastic, the price was only $100 per hour and as we have almost zero site access it was essential