I am in the northeast and just poured some footings and 8" concrete
sonotubes yesterday. The temperature was 50F. Today the temperature
was low 40's and tonight low 20's. I covered the tubes with lots of hay
and poly tarps over top. I did not use any curing accelerators or antifreeze.

My concern is the temperature will be going steadily down and in a week
or 2 the high temp might be only around 32. No matter how much hay
and tarps I put over the concrete, eventually the ground around it will
freeze. I understand that concrete should not be allowed to freeze until
it has reached a certain strength.

I also read that concrete effectively stops curing below 40F, but I am not
sure about that. I can keep the concrete from freezing for about 3
weeks more, but I may not be able to get it above to 40F during that
time. Will the concrete still cure to the desired strength so that it
will not be damaged by eventual winter freeze? Thanks,

--
Jeff