Great shop!, and hand mixing that quantity of concrete is hard work. Even to keep the mixer fed with aggregate is hard going unless there was a machine bucketing it straight into the mixer drum...
The advantage of course to handmixing is you can do it in bits that you can tackle easily, rather than have a lorry drop off 14m3 in one go and have to run round like madmen pulling it round then tamping it. Which in a building that size is equally as exhausting. Disadvantage is variations in shade of concrete with small inconsistencies in the quantities, not a big issue for a workshop but if you are trying to polish it for later it matters.
Memories of trying to power float our 150m3 house downstairs floor to a polished floor finish in one go spring to mind, during which it was at the perfect stage for floating at one end, but by the time the float got to the other end and I'd wrestled the heavy float past all the internal doorways etc, the concrete there had gone off too much and needed wetting down. We ended up tiling it
Still think I'd pick the phone up and order a wagon's worth though, well done on getting it down so quick
