As people in the industry will tell you—concrete work is a hard and hot job. And now as we come into July, known as perhaps the hottest month of the year in Calgary, this job only gets harder. 

So before you undertake any concrete project and spend hours a day with little reprieve from the sun and heat, consider leaving the job to the professionals. Even if you’re on a budget, it may be worth the extra cost to have someone else take on the project during these summer months.  

What exactly are the challenges of getting concrete work done in the summer? In this blog post, we’ll take a look at a few of them so you can make an informed decision about your next project. 

But First—How Hot Is Too Hot?

When it comes to successful concrete pouring, the temperature is everything. If it’s too cold, the concrete will set too slowly and won’t reach its full strength. If it’s too hot, on the other hand, the water content in the cement will evaporate too quickly, causing the concrete to set too fast and not reach its full strength. In short, you want to pour concrete when the temperature is just right.

Experts generally agree that the maximum temperature limit for pouring concrete is between 27°C – 32°C. And even though July in Calgary can take on an average high of 23°C, the humidity makes it feel much hotter, sitting at a balmy 30°C with the humidex.

So, what do professionals do when they’re working in extreme heat, and what is being done to mitigate the effects of high temperatures? Here at TNA Concrete, we take a few steps to ensure the success of our projects. Take a look at the challenges that typically arise during Calgary summers and how we overcome them.

The Five Challenges of Hot Weather Concreting

Now that we know how important temperature is to the success of a concrete job, let’s take a look at the five main challenges that come with working in hot weather conditions:

Step 1: Increased Evaporation Rate

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As we’ve mentioned, one of the dangers of working with concrete in high temperatures is that the water content will evaporate too quickly. This can cause the concrete to dry too quickly, making it more challenging to work with. In addition, it can also lead to surface cracking and other problems.

We employ a few ways to mitigate this problem. First, if it can be helped, we try to work in the cooler hours of the day, such as early morning or evening. We might also add an admixture to the concrete mix that will help reduce evaporation. Both are to maintain ideal moisture content in the concrete so that it sets at the right rate.

Step 2: Acceleration In Slump Loss

One of the challenges of working with concrete in hot weather is the potential for accelerated slump loss. Slump is the measure of how much a concrete mix will flow or settle. As you can imagine, if the mix settles too quickly, it can be difficult to work with and can cause a number of problems. 

This occurs when the concrete loses moisture too quickly, causing it to become stiff and difficult to work with. There are a few ways to prevent this from happening.

First, choosing the right type of concrete for the job is vital. For example, using a high-strength concrete mix will help to reduce shrinkage and cracking. Second, it’s crucial to protect the concrete from the sun and other heat sources. This can be done by using shade cloths or vented plastic sheets.

Finally, keeping the concrete moist during the curing process is essential. To improve slump retention, of which the action is often limited in time, the addition of set-retarding water reducers—typically lignosulfonates—is adequate.

Step 3: Reduced Set Times

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When concrete is mixed, the cement undergoes a chemical reaction with water that causes it to harden. This process is called hydration and is exothermic, meaning it gives off heat. In hot weather, the hydration rate increases, which means the concrete sets more quickly. This can cause several problems.

First, placing the concrete before it starts to set is difficult. Second, the finishes applied to the concrete are more likely to be damaged when the concrete sets too quickly. Finally, the rapid setting can lead to cracking as the concrete shrinks while it hardens.

To overcome these challenges, quick-setting concrete mixes or adding admixtures that slow the set time may be used. A setting retarder to slow down the hardening process can also work. 

Step 4: Plastic Shrinkage and Cracking

Working with concrete in hot weather can be challenging due to a phenomenon known as plastic shrinkage and cracking. When pouring cement in hot weather, the surface of the concrete dries out quickly, causing it to shrink. This can cause cracks to form on the surface of the concrete. In some cases, the heat might cause the concrete to expand, which can also lead to cracks.

To avoid this, we usually protect the concrete from the sun and heat by covering it with tarps, wet burlap, or shade cloths. By taking these precautions, we can help ensure that the concrete sets properly and doesn’t develop cracks.

Step 5: Reduction in Ultimate Strength

One of the challenges of working with concrete in hot weather is a reduction in ultimate strength. The water in the concrete evaporates quickly in hot weather, which reduces the amount of water available for the chemical reaction that gives concrete its strength. The resulting concrete is weaker than it would be otherwise, which poses a serious problem for construction projects, as concrete that doesn’t reach its full strength is at risk of failing.

In addition, the heat speeds up the chemical reaction, resulting in a weaker finished product. As a result, taking precautions when working with concrete in hot weather is important, such as using a lower water-to-cement ratio and adding admixtures to slow down the setting time. These steps make it possible to produce high-quality concrete even in warm conditions. Ultimately, working with concrete in hot weather requires extra care and attention to ensure that the finished product is up to par.

Need Concrete Work Done In Calgary This Summer

If you’re planning on getting concrete work done in Calgary this summer, it’s important to be aware of the challenges that hot weather can pose. Many potential problems can arise from reduced set times to plastic shrinkage and cracking. By taking precautions and working with an experienced team, you can ensure that your project is completed successfully.

Although the weather in Calgary can be a bit unpredictable during the summer, that doesn’t mean you have to put your concrete work on hold. TNA Concrete has been serving Calgary for nearly 30 years, and we are experienced with working in all types of weather conditions. Contact us today and let us know how we can help you complete your concrete project this summer!