concrete curing CSA 23.1 table 20 clarification?

[caml17]

Any Canadians can clarify something from CSA code? A23.1 looking at table 20 for concrete curing. My question is, what is meant by 10'C? Is it the ambient temperature, concrete temperature, surface temperature, or what?

"1 Basic curing 3 d at  10 °C or for the time necessary to attain 40% of the specified strength."

Thanks
Cam

 

[bb29510]

basically it means cure at above freezing. 10c equal 50 f, most spec calls for curing at 72f, but your spec sounds like field cure above 50f