At last! The culmination of weeks of hard work – the concrete is going to be poured today!
Owen Davis (Start to Finish Concrete) came with a helper (Ty), and had the whole pad poured in about an hour and a half.
It is hard physical work – young man’s game – and I was happy to step back and let the pros handle it. There is actually quite a bit more to doing concrete work well than meets the eye. 
Concrete has been with us since before the Romans, and there are dozens of variations of mixtures for different purposes and conditions, and a mismatch (using the wrong mix in the wrong place or conditions) will lead to a failure, such as cracking, scaling, flaking, or spalling. A discussion of concrete was part of the “Materials Science” course in my degree studies, and I was really surprised at the variety and complexity of concrete products that are available.
Owen was able to level the pad pretty much by eye. I had chalk lines snapped on three sides, and a 2×12 on the south edge, so this was not a typical pour where there is a form around all four sides so you get to level it with a board across the form.
I did make a calculation mistake. When I compacted the gravel, I used a laser level to check the resulting depth for the concrete pour. In some places, it was going to be 5 inches thick, in others, only 3 1/2 inches thick. I figured it would all average out to approximately 4 inches, from which I derived my calculation that we needed 2 cubic yards of mud.
Owen was two wheelbarrows away from filling the pad when the message came from the driver that there was no more mud, so Owen said it was time to “break out the concrete stretcher.”
Simply, he moved some of the material from the lowest edge (the entire pad slopes away from the house by an inch over twelve feet) and moved it to the void where we had run short. In the end, there is no way you’d know if you had not seen the process, which takes me back to the whole concept of leaving certain jobs for the experts.
For many years, I’ve been saying that the definition of mastery is knowing how to hide your mistakes!
We wanted the concrete to be finished with exposed aggregate, so it would match the rest of the existing concrete work. So Owen sprayed the wet concrete was sprayed with molasses and went to lunch. Sugar slows the curing of cement, so applying molasses to the surface keeps the top layer soft so it can be washed away a couple of hours later, exposing the gravel underneath.
In two days, I will power wash the surface, and I can set the hot tub on it in three days. In five days, we could drive a car on it, if we wanted to. Which we don’t.
We ordered a stronger mix (6 bag, 4,600 psi) because we will have a giant bucket of water (a spa with almost three tons of water) sitting on it forever.
Next – we get the hot tub moved, and I finish all the detail work!