The Hoover Dam and Curing?

The Hoover Dam contains (I read) 2.6 million cubic metres of concrete. Yet it was poured in relatively small blocks in order to expedite the curing process. Why? If curing is a process of hydration, why is this not a local process, independent of the volume of the concrete? I read also that if poured in one fell swoop, the Dam would have taken 125 years to cure. I'm not certain I've fully understood the curing process if it is truly volume dependent.

Dornfield (author) 1 month ago

Actually as an addendum to my own question, I notice that in Lesson Two on curing, the video of the 'Han Solo' silicone molds labelled 7.5 hours, the three smaller molds are clearly curing before the larger one to the left. So size does matter? What impact (if any) does the rate of curing have on strength?

Volume does matter. You want concrete to cure slowly, which will yield a stronger product. However, there's a practical limit to the length of time to wait (in your example, 125 years is a long time).

With the Hoover Dam example, imaging pouring the entire structure at once only to find out the ratio was off and the dam wasn't as strong as it needed to be. Pouring in smaller batches ensure quality and ratio consistency, as well as a faster cure time.