When concrete is placed in cold weather, more caution must be used since early-age concrete might become damaged and unusable if it is allowed to cool below freezing. It is also important to realise that strength will develop much more slowly in colder temperatures. This is a handy guide to concrete in colder weather.
Concrete Use in Very Cold Weather
It is important to consider two distinct temperatures when working with concrete. These are the real temperatures of the concrete and the surrounding air, and it is important to distinguish between these two. The water in the mix may freeze and expand, resulting in cracks and possible spalling if recently laid concrete is exposed to temperatures below freezing. The concrete would become hazardous and useless as a result. For the concrete to reach a minimum strength of 2 N/mm2, thermal blankets should be employed to keep the temperature above 5°C for at least 24 hours. The steps that must be implemented depend on how severe the weather is. This can be separated into two groups for concrete placement purposes.
Temperatures below 5°C, But Not Frost
Although the concrete will take longer to achieve compressive strength, there is little risk of irreversible damage when the air temperature is low but does not fall below 0°C. It’s crucial to consider formwork striking times and avoid removing it too soon. Because of variations in cement composition, mixes, and ambient air temperatures, it is hard to predict when formwork should be struck. This process can be accelerated if necessary by adding accelerators to speed up the hydration process or by utilising mix designs with a higher cement concentration.
Frosty Conditions
Concrete must have a temperature of 5°C or higher during the day and overnight. Sometimes, the provider won’t be able to do this, and the customer will have to decide whether to accept responsibility for the concrete and its maintenance or to cancel the concrete pour. Frost blankets, insulated formwork or temporary covers should be used for protection, and space heaters should be used to raise the surrounding temperature. Make sure that there is no ice or snow on the sub-bases, formwork, reinforcement, or placing equipment before pouring concrete.
Cempump offers swift and professional concrete services. Contact our team to discuss your requirements on 01332 410021.
