Pouring Concrete in Cold Weather

Anyone who regularly pours or handles concrete will be aware that doing so in mild or warm conditions is always desired. 

In fact, the optimum temperature when pouring concrete is considered to be 10°C or above. In many cases, builders or contractors will want to wait for a clear, sunny day to pour their concrete mix but this is not always possible. 

In particular, when you consider the unpredictable, and often wet, conditions that are on offer here in the UK, you can see how it might be impractical to wait for a nicer day! However, pouring concrete in cold weather is also an important factor to consider. 

During the winter months, when the temperature inevitably drops, extra precautions may need to be taken as a whole host of problems can occur if concrete freezes. 

In this article, we’ll take a look at what needs to be done when pouring concrete in cold weather to ensure you are able to maximise your mix. 

Read on to find out more.

Can Concrete Be Poured In Cold Weather? 

First, let’s take a look at whether concrete can be poured in cold weather at all. 

You can never be certain of the weather conditions on any given day, but colder or lower temperatures are far more likely between November and February. 

Concrete can be poured no matter what the temperature is, however, certain mitigations will need to be taken if the temperature drops below 3°C. This is because this is the level where it is considered that the mix is being exposed to cold temperatures. 

We’ll go into further detail regarding how you can prepare your mix during the cold weather, but it’s important to understand that the biggest threat to concrete is freezing temperatures below 0°C. If concrete is poured onto a base that is in the minus temperatures or it reaches them itself, then a whole host of problems can occur.  

What Happens If Concrete Freezes?

While the UK doesn’t see freezing temperatures throughout winter like other countries may experience, it is still fairly common to see the mercury dip below 0°C during the winter months. 

Freezing temperatures can be extremely damaging to your concrete mix, and you should avoid letting your concrete freeze at all costs. 

Concrete is made from a number of ingredients, including water. It is this water that the freezing process can adversely impact. Water is the main component of every concrete mix and it must be protected from freezing as it is poured. To be more precise, concrete needs to be protected from freezing for at least 24 hours when it has been poured. 

This is because when ice forms in the concrete before it has properly set, the water crystal will start to expand and this will negatively impact the necessary hydration process. This can cause the concrete to lose up to 50% of the concrete’s strength. Concrete is a preferred building material primarily due to the durability and structural stability it offers. Therefore, if freezing does occur and this is compromised, it is clear to see how it can have negative consequences for your project. 

A Guide To Pouring Concrete In Cold Weather 

Now we’ve established that you can pour concrete during the cold weather with certain measures in place, let’s consider the best way to do this.

Check The Temperature 

If the day feels cold or you’re planning on pouring during the winter months, you should always check what the temperature is before proceeding. If the air temperature is less than 3°C then you will need to make certain mitigations. 

Check The Sub Base

Before pouring, you should also check the temperature of the sub base. The sub base is the surface that your mix is being poured onto and if it has become frozen then you will not be able to pour the mix at this time. This is because the concrete you are pouring must not freeze for the first 24 hours or it will become damaged and the durability will be compromised. When the weather gets colder, many contractors will put measures in place to protect the sub base from freezing. 

Any trenches or cavities that are due to be poured into should also be checked. 

Use Thermal Blankets

If you suspect cold weather is on the horizon, thermal or insulating blankets can be used. Place them on the sub base in advance of pouring (usually the night before) as this will keep the base at the appropriate temperature. 

You could even hook up some portable heaters to warm the area further. 

Protect The Mix When It’s Been Poured 

As previously mentioned, the mix you’re pouring needs to be protected from freezing for at least 24 hours after it has been poured. 

With this in mind, if it’s a very cold day then you should utilise the thermal blankets once again to keep the concrete warm and prevent freezing from happening. 

Can Concrete Be Poured In Wet Weather? 

We’ve covered pouring concrete in cold weather, but what about wet conditions?

Usually, dry weather is necessary for pouring concrete as rainwater can seriously compromise the strength, durability and quality of your mix. 

While postponing the work might seem inconvenient, it’s actually usually preferable to going ahead in the rain. This is because the damage the rain can cause to the concrete can often be so severe, that you may have to pour it again anyway. 

Here at Concrete Supply UK, we’re vastly experienced in providing customers across the country with leading different types of concrete mixes.

Extremely knowledgeable in the concrete industry, we always formulate bespoke mixes that perfectly align with the requirements and preferences of your project. In addition to this, we will also make sure you always have the right concrete grades and quantity you need to get the job done to the required standard and which minimises waste and expense. 

For more information on how we can help, get in touch with our team today.