Clitheroe
Shap
Horwich, Bolton
Chorley
Horwich, Bolton
Clitheroe
Shap
Horwich, Bolton
Chorley
Horwich, Bolton
While the UK doesn’t often see heatwaves, when it comes to concrete in hot weather, planning and preparation are essential.
High temperatures can accelerate the setting time of concrete, reducing the window for placement, finishing, and proper curing. If not managed correctly, this can lead to surface cracking, compromised strength, and an uneven finish.
As a trusted supplier of concrete across the North West through our sister company AMIX, we understand the challenges and offer ready-mix solutions designed to withstand warmer conditions.
Warm, dry, and windy weather speeds up the rate at which moisture evaporates from freshly poured concrete. This has a direct impact on the curing process.
Concrete cures faster in hot weather, and while rapid curing may seem efficient, when it happens too quickly, the concrete doesn’t have enough time to hydrate fully, resulting in surface shrinkage, cracks, and reduced structural integrity.
You may be wondering how hot concrete can really get, especially as we often don’t experience high temperatures in our climate. In warmer conditions, the internal temperature of curing concrete can easily exceed 30°C and sometimes reach over 60°C due to an exothermic chemical reaction.
This internal heat, combined with external temperatures, can push the concrete past its optimal curing range, causing thermal stress and cracking.
That’s why hot weather concrete techniques, such as adjusting the mix design or modifying curing practices, are so important.
Without proper control, hot weather can introduce a range of issues that compromise the quality of your concrete. One of the biggest concerns is rapid moisture loss. As water evaporates too quickly from the surface, it reduces the time available for finishing and can weaken the bond between cement particles.
This accelerated setting can also cause thermal cracking, particularly in larger pours. As concrete heats up during curing, internal stresses develop.
If the temperature drops too quickly after pouring, especially overnight, these stresses can cause unsightly and structurally significant cracks.
In addition, you may notice surface scaling or shrinkage cracks, which occur when the top layer dries and sets before the internal mix has a chance to fully cure. These surface flaws not only affect the appearance of the finished slab but can also shorten its lifespan.
While concrete can technically be poured in a wide range of conditions, most industry guidelines suggest that temperatures above 30°C pose a risk to fresh concrete.
At this level, the combination of heat, low humidity, and wind can accelerate evaporation and cause the concrete to set far quicker than intended.
As a general rule, any ambient temperature above 30°C should prompt caution, and additional measures should be taken to manage mix temperature, placement speed, and curing methods. Early morning or late afternoon pours are often more manageable, and using specialist admixtures or pre-cooled materials can help slow the set and retain workability.
One of the most effective ways to combat cracking is to start with the right mix design.
Adjusting the water-to-cement ratio is crucial. Too much water can weaken the final structure, while too little can make the mix unworkable in hot conditions.
To help strike the right balance, admixtures such as retarders can be added to slow down the setting time, giving you more control during placement and finishing. These types of concrete admixtures are essential components of hot weather concreting, helping to preserve workability without compromising strength.
Timing also plays a vital role. To avoid the harshest heat of the day, aim to pour concrete during the early morning or late afternoon.
This helps reduce the temperature of the pour site and gives the concrete a better chance to set gradually. Pouring during cooler hours also limits the risk of rapid moisture loss caused by direct sun exposure.
Finally, it's important to protect the pour area during and after placement. Simple steps like setting up windbreaks, erecting temporary shading, or using fine mist or fog sprays can slow down surface evaporation and help the concrete cure evenly.
These methods create a more controlled environment for the mix, reducing the chance of early cracking and improving the overall finish.
By following these practices, you’ll have a much better chance of avoiding common issues associated with hot weather concreting.
At Armstrongs, we understand the challenges of working with concrete in hot weather. With five quarries strategically located across the North West, AMIX is your local supplier of high-quality ready-mix concrete tailored to the region’s summer conditions.
Whether you're working on a small residential project or a large commercial site, we provide mixes specifically formulated to help you get the job done right, even during the hottest months of the year.
Our team works closely with contractors to provide the right concrete mix, which can include admixtures like retarders to slow the setting time and improve workability.
By adjusting the water-to-cement ratio, using the right type of aggregates, and adding special additives, we ensure that your concrete stays workable for longer, reducing the risks associated with hot weather, such as cracking or premature hardening.
We also offer expert advice to help you optimise your pours. If you're unsure how to modify your mix or timing to manage high temperatures, our experienced team is always ready to offer guidance, helping you avoid costly mistakes.
Plus, our local quarries mean we can deliver fresh, high-quality concrete to your site quickly, keeping your project on track without the long waiting times often associated with larger suppliers.
In addition to our tailored mixes, we also provide regular monitoring of weather conditions and can advise you on the best practices to use on each job site. With Armstrongs by your side, you’ll have the confidence that your concrete will perform optimally, even under challenging heat.
Fresh concrete is typically around 10–25°C, but in hot weather, it can rise rapidly, especially if aggregates or water are warm. If not properly managed, the temperature of the mix can easily exceed 30°C, making it more challenging to work with.
Yes, heat accelerates hydration, which causes the concrete to set faster. While this may seem like an advantage, without the right precautions, it can lead to reduced strength, surface cracking, and other issues. This is why it’s crucial to slow down the curing process with proper curing methods and mix adjustments.
Moist curing is ideal. Use water spraying, wet coverings (such as burlap), or curing compounds to retain moisture. These methods help prevent the rapid evaporation of water, ensuring the concrete cures evenly and strengthens properly over time.
Yes, but only after the concrete has set enough to avoid displacing the surface or causing damage. Keeping the surface damp helps reduce cracking and supports the proper hydration process.
Always make sure the concrete is not too soft before applying water, as premature wetting can interfere with finishing.
Yes, but with precautions. When pouring concrete in hot weather, it’s essential to adjust the mix, schedule pours during cooler parts of the day, and use effective curing methods.
Whether you’re using chilled water, retarders, or misting systems, Armstrongs can provide guidance and supplies to help make your pour successful even in extreme heat.
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