On the other hand, I was astonished to learn that freshly mixed concrete, in the truck, is exothermic, generating heat. Too much heat is bad for the mix. An acquaintance was a contractor for fed.gov, and rejected many, many truckloads of concrete, in Tejas, in summertime, for being over allowed temp. He averred that the contractor would have multi-hundred point blocks of ice put thru the equivalent of a tree-shredder, the discharge going into the trucks as the mix is generated in them. I don't know if I learned something that day, or if my acquaintance learned that I'm gullible. I never bothered to follow up w/ research. It's a great story, so it ought to be true.