Pour concrete in hot weather? It might sound like a logical thing to do, but that isn’t the case.
Hot summer days present a challenge for concrete work. While bright sunshine might seem ideal for outdoor projects, it can spell disaster for a concrete pour.
If you pour concrete in hot weather, it can wreak havoc with your project.
The good news is that you can still achieve professional results even in punishing heat (if we ever get any in the UK!) with the right approach.
This article highlights the best tips to pour concrete in hot weather.
The Hidden Dangers of Heat in Concrete Pouring
Logic suggests that heat would accelerate concrete strengthening, but the reality reveals a more complex and potentially problematic relationship between temperature and concrete curing.
The problem is that speed kills concrete strength because it sets too fast. This rapid setting prevents the internal crystal structure from forming correctly. It’s like rushing to build a house without laying a solid foundation. Each temperature increase weakens the final product, which can cause concrete durability problems such as cracking.
In addition, heat makes the water in concrete evaporate quickly, making it harder to work with. Many people add extra water to make the mix manageable again. However, that dilution further weakens the concrete mix.
It’s a lose-lose situation: you struggle to handle stiff concrete or end up with a weaker final product.
The worst damage often happens as concrete dries. The hot surface loses water faster than the deeper layers, creating internal stress. The surface can blister or crack as moisture gets pulled up from below.
These aren’t just cosmetic issues – they can seriously compromise your concrete’s durability.
Follow these 6 tips to make the most of the hot weather without compromising your concrete project.
#1: Plan The Best Time for Your Concrete Pour
Smart scheduling makes all the difference when you pour concrete in hot weather. The hot afternoon sun can spell disaster for your project, but there’s a simple solution: work when it’s cooler.
Early mornings offer ideal conditions. The air is crisp, surfaces are still cool from the night, and you’ll have several hours before the real heat kicks in. Depending on the temperature, late afternoon can be your next best bet if morning doesn’t work.
Read: Concrete Weather Conditions Top Tips
Consider the temperature patterns in your area. Check your local forecast and plan accordingly. Many professional crews start at dawn to beat the heat entirely.
Remember that fighting the afternoon heat isn’t worth the risk. Those few hours of delay can mean the difference between concrete that lasts decades and concrete that starts cracking within months.
#2: Block the Sun: Essential Shade for Concrete
Keeping your concrete out of direct sunlight is crucial – and easier than you might think. The right shade can dramatically slow drying time and prevent surface damage if you pour concrete in hot weather.
You don’t need fancy equipment. Basic shade sails work great. So do large umbrellas. Even sheets of plywood propped up strategically can make a big difference. The goal is simple: Block those harsh rays from hitting your fresh concrete.
For the cost of a few basic materials and ten minutes of setup, you can significantly improve your chances of a successful concrete project.
#3: Pre-Wet Your Forms: A Quick Temperature Fix
Dampen your forms with cold water before you pour. It’s that simple. This quick step stops hot forms from stealing moisture from your fresh concrete mix.
Cold forms mean better concrete. When your forms are pre-soaked and cool, they work with your mix instead of against it. The concrete keeps its moisture longer and sets more evenly.
The process takes just minutes but can save your entire pour. Keep a hose handy and give those forms a good soak – it’s one of the easiest ways to protect your concrete on hot days.
Read: Ready Mix Concrete vs Site Mixed Concrete – Which Is Best?
#4: Retarding Admixtures: The Hot Weather Solution
Mix in a retarding admixture to buy yourself crucial working time. These speciality chemicals slow down how fast your concrete sets – precisely what you need when it’s hot outside.
Retarders give you extra time to properly place and finish your concrete instead of racing against rapid hardening.
The small cost of adding a retarder pays off in better results. You’ll have time to work carefully instead of rushing, leading to stronger, more durable concrete.
Flowmix can advise on the best admixtures for hot weather.
#5: Use Curing Compound or Curing Blankets
Curing blankets are extensive fabric sheets laid over concrete to shield it from sunlight and maintain moisture levels. Similarly, a curing compound is a liquid applied to the concrete’s surface to accomplish the same purpose.
#6: Shorten Timescales
The longer it takes to transport, mix, and place concrete, the more it will heat up. To minimise this happening, consider sourcing concrete from a local supplier like Flowmix Gloucester or Walsall.
Alternatively, mixing the concrete on-site instead of pre-mixed deliveries can help.
How Flowmix Can Help With Your Project
Flowmix has two plants, Gloucester and Walsall. We provide ready-mix concrete, mix on-site and liquid screed.
In addition, you can hire a 200′ concrete line pump to reduce manual labour and associated costs, increase efficiency, reduce wastage and clean up. Moreover, we also provide interlocking concrete blocks for temporary or permanent barriers.
Flowmix has the BSA-approved Ready Mix Concrete Kitemark KM683844, a certification that “confirms a product or service’s claim has been independently and repeatedly tested by experts” (source BSI).
Flowmix Tewkesbury: 01684 217888 Flowmix Walsall: Tel: 01922 741731