open mike- "doesn't cement/concrete have requirements temperature-wise? i think it generates heat at first from the chemical reactions in the lime stone or something??"

Yes. In our case by pouring into the insulated forms we'll gain the heating of the chemical reaction being held in for the curing period. They'll probably add a sack of calcium chloride for a further assist in this cold.

Congratulations to you too, on your building permit. That's great news!