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Associated Products | Hot Water

American Concrete Institute (ACI) committee 306 defines cold weather as “a period when for more than 3 consecutive days the following conditions exist: 1) the average daily air temperature is less than 40°F; 2) the air temperature is not greater than 50°F for more than one-half of any 24-hour period.” The average daily air temperature is the average of the highest and lowest temperatures occurring from midnight to midnight.

Hot water can be added at the batch plant during batching to accelerate set time and strength gain. Cold weather concreting usually starts during fall and continues until spring.

Cold weather concreting difficulties are mainly caused by low ambient temperatures and lack of protecting concrete from freezing. These conditions adversely affect the quality of concrete because the rate of setting is extended, early strength development is delayed and the potential for plastic shrinkage cracking is increased. The chart below highlights the use of hot water and or accelerator to decrease setting and improve early strength development.

Cold Weather Options

		Approximate Reduction of Standard Set Time
Temp.	Approximate Standard Set Time	Hot Water	1% Accellerator	2% Accellerator	Hot Water & 1% Accellerator	Hot Water & 2% Accellerator
60ºF	6 - 8 Hrs	Negligible	30 - 45 Mins	1 - 1.5 Hrs	45 Mins - 1 Hr	1.5 - 2 Hours
50ºF	10 - 12 Hrs	20 - 30 Mins	45 Mins - 1 Hr	1.5 - 2 Hrs	1 - 1.5 Hrs	2 - 2.5 Hrs
40ºF	12 - 14 Hrs	30 - 45 Mins	1 - 1.5 Hrs	2 - 2.5 Hrs	1.5 - 2 Hrs	2.5 - 3 Hrs
30ºF	14-16 Hrs	40 - 60 Mins	1.5 - 2 Hrs	2.5 - 3.5 Hrs	2 - 2.5 Hrs	3 - 4 Hours
20ºF	Set does not occur. Concrete will freeze.

**Concrete must be protected to eliminate or minimize the evaporation of moisture. Moisture is essential for efficient hydration performance

*** Hot water offers initial temperature increase benefits in addition to a slight decrease in set time