One thing I like about reading judicial opinions is that you often learn something new. Though, as a matter of fact, I already knew this part:
"The concrete that Granitrock produces is a perishable product that cannot be
stored. It is mixture of rock, sand and cement. When water is added to the mixture, it
creates a chemical reaction that causes the mixture to harden. For this reason, when there
is concrete in the drum of a mixer truck, the drum must rotate at all times to prevent
hardening. In addition, freshly batched concrete must be poured within 60-90 minutes to
ensure its structural integrity. One of the duties of the concrete mixer drivers is to monitor
the rotation of the truck drum."
I knew that because one of my relatives (in North Carolina) used to drive a concrete truck. With an emphasis on "used to". One night, after work, he had far too much to drink, drove the truck -- which was still full of concrete for the next day's pour -- home, parked it, and slept it off. But neglected to keep the drum spinning. So when he woke up the next morning, he had a drum with several tons of set concrete. In the drum.
As you can imagine, he was promptly fired.
So, yes, keep that drum spinning.
P.S. - Is the company "Graniterock" or "Granite Rock"? The Court of Appeal's opinion repeatedly says that it's "Graniterock" (e.g., "Graniterock is a concrete company that manufactures, delivers and pours concrete.") But caption of the opinion says that the defendant is "Granite Rock Co." The web site of the company, for what it's worth, appears to say "Graniterock". Maybe one's a d/b/a. (Making it more confusing, in the quote from the opinion I pasted above, the Court of Appeal also calls the company "Granitrock" -- without the e. I'm pretty sure that's just a typo, though.)