Cold weather concrete production can be a challenge
Under cold conditions and in freezing temperatures, water freezes and inhibits concrete’s hydration process. Unaided, cold weather concreting is slow and therefore expensive. In addition, the resulting product is often a poor quality concrete with:
Avoiding freezing before the concrete achieves 5 MPa compressive strength is part of the regulation (NS 3420 in Norway, for example).
An “antifreeze” product prevents water from freezing before or during the hydration process. This can be done by:
Inside the concrete, including its outer regions attaching the mold, the temperature has to be at least 5°C, to guarantee sufficient reactivity and availability of water. At minimum, the concrete should have 5 MPa strength prior to freezing.
NitCal®, as a concrete setting accelerator, counteracts the freezing process by provoking an earlier start of concrete heat release and therefore earlier strength development. Concrete can be produced at ambient temperatures down to -10°C using NitCal at certain conditions.
NitCal® and Sodium nitrate do not reduce the freezing point at the concentrations commonly used for set acceleration or antifreeze. To get the antifreeze effect, higher doses are required.
Alternative methods of cold weather concreting are often costly, impractical and environmentally challenging techniques such as:
Yara has over the last years developed a better understanding of the mechanism of NitCal as antifreeze in concrete and mortar. Through this we have also developed our Superantifreeze admixture concept for deep frost (down to -15°C). Yara NitCal is able to support effective concreting even in the coldest Australian winter.