My friend poured a HUGE foundation and retaining wall for a new barn.
He put the cement and sand in the HF concrete mixer,, (ONLY cement and sand!!, no stone) added water and let it mix.
Then he would scoop up an appropriate amount of crushed stone in the loader bucket.
The contents of the mixer were then dumped on the stone in the loader bucket.
A few swipes with a hoe, the concrete was mixed, then he used the loader to dump the concrete in the form.
He ended up with really nice, and low labor concrete,, poured in a location that a concrete truck could not reach.
Since there was no stone in the HF mixer, a HUGE batch of sand and cement could be mixed,,,