confusion over portland-cement curing with freezing

I am building my own concrete block garage and trying to get some work done before winter finally ends my work year. I knew that Saturday night
was going to get cold and drop below 32 F and during the day it was only in the 40s F. But I went ahead anyway to mortar some joints.
I know they lay concrete and cement all year round by building heat tents on job sites. But I wonder as to the curing process of mortar? Does it take as long as concrete? And what are the working parameters of mortar and cold temperatures?
I know that in the curing of cement that it releases heat itself and am wondering how low of a temperature below 32 F that it begins to damage the mortar cement in curing.
Archimedes Plutonium, a snipped-for-privacy@hotmail.com whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
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[laying concrete at low temperatures]

Do a search for "cold weather concrete" ... or have a look at: http://www.mbu.masterbuilders.com/cold_weatherconc.pdf http://www.cement.ca/cement.nsf/internetE/34440F8E621CC008852568AA006BAC78?opendocument
Andrea
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Some years ago, I had a new garage put up. Between the alley and the garage there was a 24-30 inch wide strip where weeds grew in profusion. I had concrete laid there, but it was Novemberish (Minnesota) and the temperature got below freezing but with full sunlight the next day the temps went up to around 40-45. The following spring I noticed several spots, 6-8 inches in size, where irregular surface spalling occurred. I theorized that curing proceded irregularily and where weak a thin water layer could freeze more easily causing spalling fracture thin zones. Lesson - use a tent and artificial heat source uniformally distributed during the 24 hours following laying of concrete AND DO NOT flood with water.
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