Will Concrete Set in Cold Weather?

How Temperature Affects Concrete Setting

Concrete sets through a chemical process called hydration. During hydration, water reacts with cement particles to form bonds that give concrete its strength. Temperature directly influences how quickly this reaction occurs.

The Science Behind Cold Weather Curing

When temperatures drop, the hydration process slows considerably. At 10°C, concrete takes approximately twice as long to gain strength compared to concrete poured at 20°C. Below 5°C, the reaction slows even further, and the concrete becomes vulnerable to frost damage before it reaches adequate strength.

The critical period occurs during the first 24 to 48 hours after pouring. During this time, concrete must be protected from freezing temperatures. If fresh concrete freezes before reaching a compressive strength of approximately 3.5 MPa, ice crystals form within the mixture and permanently damage the internal structure. This damage reduces the final strength by up to 50% and cannot be repaired.

Minimum Temperature for Pouring Concrete

Industry guidelines recommend maintaining concrete temperature above 5°C during placement and for at least 48 hours afterwards. This threshold ensures the hydration process continues at an acceptable rate and the concrete gains sufficient strength to resist frost damage.

Temperature Guidelines

Follow these temperature considerations for cold-weather concreting:

• Air temperature should be above 5°C and rising at the time of placement
• Concrete temperature at delivery should be between 10°C and 20°C
• Ground temperature should be above freezing before pouring
• Night-time temperatures should remain above 0°C for at least three consecutive days after placement

A reliable Concrete Supplier like Pro-Mix Concrete monitors weather forecasts closely and advises customers on optimal pouring times during the winter months.

Did You Know?

The ideal temperature for concrete curing is between 10°C and 20°C. At temperatures below 5°C, the hydration process slows by more than 50%, significantly extending the time required for concrete to reach safe strength levels. 

Tips for Successful Cold-Weather Concrete Pours

Proper preparation and protection make cold-weather concreting achievable. These practical steps help ensure your project succeeds despite lower temperatures.

Before the Pour

Preparation begins well before the concrete arrives on site. 

• Remove all ice, snow, and standing water from the pour area before delivery. 
• Warm the subgrade if ground temperatures are near freezing to prevent rapid heat loss from the fresh concrete. 
• Ensure formwork is completely free from frost and ice, as frozen surfaces cause the concrete to lose heat quickly and cure unevenly.
• Have insulating blankets and protective coverings ready and accessible before the concrete arrives. 
• Schedule delivery during the warmest part of the day, typically between late morning and early afternoon, to maximise working time before temperatures drop.

During and After Placement

Protecting fresh concrete from cold temperatures requires immediate action once placement begins. 

• Place and finish concrete as quickly as possible to minimise heat loss to the surrounding environment. 
• Cover exposed surfaces with insulating blankets immediately after finishing to retain the heat generated during hydration.
• Use windbreaks around the pour area to prevent cold wind from accelerating heat loss.
• Monitor concrete temperature regularly during the first 48 hours using embedded thermometers or infrared sensors. 
• Maintain protection until the concrete reaches adequate strength, which typically takes longer in cold conditions.

Cold Weather Concrete Mix Adjustments

Standard concrete mixes can be modified to perform better in cold conditions. These adjustments help maintain workability during placement and accelerate strength gain during curing.

Common Modifications

Professional suppliers offer several options for cold-weather projects:

• Accelerating admixtures speed up the hydration process and reduce setting time without compromising final strength
• Higher cement content generates more heat during hydration, helping maintain adequate temperatures within the concrete mass.
• Heated mixing water raises the initial concrete temperature, providing a head start before heat loss begins.
• Air entrainment improves freeze-thaw resistance in the hardened concrete, extending service life in cold climates.

When to Avoid Pouring Concrete

Despite available precautions, some conditions make concrete placement inadvisable. Recognising these situations prevents wasted materials and failed projects.

Avoid pouring concrete when air temperatures are below 0°C with no warming trend expected. Frozen ground that cannot be adequately thawed before placement creates problems with heat loss and uneven curing. Snow or freezing rain forecast during placement or initial curing poses significant risks to the fresh concrete surface.

Projects should also be postponed when adequate protection materials are unavailable or when nighttime temperatures will drop below -5°C within 48 hours of placement. The risks of concrete failure in these conditions outweigh the benefits of proceeding with the pour.

Bottom Line

Concrete can set successfully in cold weather when proper precautions are taken. The key factors include maintaining adequate temperatures during the critical first 48 hours, using appropriate mix designs, and protecting fresh concrete from freezing conditions.

Working with an experienced, ready made concrete supplier makes cold-weather projects significantly easier. Professional guidance on mix selection, delivery timing, and protection methods helps ensure your concrete achieves full strength despite challenging temperatures.

At Pro-Mix Concrete, we supply quality concrete throughout London and the surrounding areas with same-day and next-day delivery available. Our certified team provides expert advice for projects in any weather condition. We offer ready mix concrete, mix on site concrete, and concrete pump hire services for residential, commercial, and industrial projects.

Get Your Free Consultation: 020 7458 4747