Mixing concrete in cold weather .

It is OK to use admixtures for concrete, but not mortar

Satisfactory anti-freeze agents for masonry mortars do not exist. Such admixtures are not recognised in any British Standard.

Admixtures for concrete intended to provide protection by increasing the rate of heat generation, by the hydration of cement, are ineffective in mortar. In mortar the mass of cement in a given volume of masonry is too small relative to the thermal capacity of that masonry.

When frosty conditions are forecast it may seem advantageous to attempt to accelerate the setting of mortar. In practice no suitable admixtures are known that would not have an undesirable effect on the masonry. Calcium chloride or admixtures based on this salt may lead to subsequent dampness of the wall or corrosion of imbedded metals, including wall ties, and should not be used. It is understood that other materials that might be considered, such as formates, are also potentially corrosive. Furthermore, some accelerators which have been investigated are ineffective at near freezing temperatures, even though they operate normally at higher temperatures.

There is little experience of the successful use of any admixture in providing frost protection by depressing the freezing point of the mixing water. Some substances that might seem to be suitable for this purpose, e.g. ethylene glycol, are known to adversely affect the hydration of cement.

Winter working calls for thermal protection to prevent damage to newly laid mortar by low temperatures.

ian wright said:

Kerry Jackson said:
3 degrees and rising

Replies

Keith Barker February 20, 2010 at 10:52am

CEMEX cold weather concrete datasheet
Kieran Ray February 22, 2010 at 6:41pm

If you use frostproofer, which can be brought from most builders merchants will allow concrete mixing down to
-15!
I know maybe I shouldn't have otherwise, but with this i managed to mix concrete when the water in the mixer froze when it was off for only 10 mins! At a guess id say it was about -5, just make shure all concrete work gets coverd over.
Jackson's Landscape Design February 22, 2010 at 6:44pm

3 degrees and rising Eliot
Boxelder Landscapes February 22, 2010 at 6:50pm

http://cemexliterature.co.uk/pdf/Concrete_ColdWeatherConcrete.pdf

Hope this helps
RICHARD BICKLER February 22, 2010 at 7:08pm

3 degrees and rising should allow you to lay concrete/mortar etc, always use the correct admix as well

stuart ralph said:
http://cemexliterature.co.uk/pdf/Concrete_ColdWeatherConcrete.pdf

Hope this helps
Eliot Saieva February 22, 2010 at 8:13pm

Thanks , all ! Purchased frost proofer first thing & had a good day . Cheers Eliot .
Tim Horner February 22, 2010 at 8:55pm

probably better to use rapid cement or high early strength cement if you mixing concrete for fence posts. They will also help when working in cold conditions as the set earlier.

Eliot Saieva said:
Thanks , all ! Purchased frost proofer first thing & had a good day . Cheers Eliot .
Jackson's Landscape Design February 26, 2010 at 11:02pm

3 degrees and rising
ian wright February 27, 2010 at 10:23am

Kerry Jackson said:
3 degrees and rising
ian wright February 27, 2010 at 10:26am

It is OK to use admixtures for concrete, but not mortar

Satisfactory anti-freeze agents for masonry mortars do not exist. Such admixtures are not recognised in any British Standard.

Admixtures for concrete intended to provide protection by increasing the rate of heat generation, by the hydration of cement, are ineffective in mortar. In mortar the mass of cement in a given volume of masonry is too small relative to the thermal capacity of that masonry.

When frosty conditions are forecast it may seem advantageous to attempt to accelerate the setting of mortar. In practice no suitable admixtures are known that would not have an undesirable effect on the masonry. Calcium chloride or admixtures based on this salt may lead to subsequent dampness of the wall or corrosion of imbedded metals, including wall ties, and should not be used. It is understood that other materials that might be considered, such as formates, are also potentially corrosive. Furthermore, some accelerators which have been investigated are ineffective at near freezing temperatures, even though they operate normally at higher temperatures.

There is little experience of the successful use of any admixture in providing frost protection by depressing the freezing point of the mixing water. Some substances that might seem to be suitable for this purpose, e.g. ethylene glycol, are known to adversely affect the hydration of cement.

Winter working calls for thermal protection to prevent damage to newly laid mortar by low temperatures.

ian wright said:
Kerry Jackson said:
3 degrees and rising