Believe it or not, the title to this article is a question that is asked pretty often. But the truth is, there isn’t an answer. Well, this is not technically true. Traditionally, concrete is poured at between 40- and 60-degrees Fahrenheit and, even today, this is broadly accepted to be the optimal temperature range. However, the matter is complicated somewhat by the fact that it is actually possible to pour concrete at colder and warmer temperatures. And sometimes, this is even necessary.
So, there isn’t really one answer to this question, but if you find yourself in the position of having to repatch your concrete driveway potholes at the height of summer, or if you need to lay a driveway or a road in a cold climate, then there are different ways of tackling the problem. Before going on to the different tips for pouring concrete in difficult temperatures, it’s worth going into a bit more detail about the relationship between concrete and temperature.
Temperature and Concrete
The crucial thing to remember is that it is not only the temperature when you are mixing and laying the concrete that is important. The temperature as the concrete is setting is also vitally important as it needs to set properly. This happens at higher and at lower temperatures.
At lower temperatures, concrete will set much weaker. This is because the specific chemical reactions that turn the concrete hard are slowed down – as is a constant across all chemical reactions – and hence resulting in weaker concrete that can crack much more easily. It might even look as if the concrete is fine after the job is done, but you’ll soon enough learn that the concrete’s life has been reduced to a fraction of what it should be – or the concrete will simply crack the moment it comes into contact with a significant load.
At warmer temperatures, the same problems are caused, but for quite a different reason. At higher temperatures, the water inside the concrete will evaporate. Water is essential for concrete to set and so this process will be disturbed if sufficient moisture is suddenly absent. This leads to similarly substandard concrete that is prone to cracking and shrinkage.
Tips for Pouring Concrete in Cold Weather
The concrete paving experts at Parking Lot Pros advise that concrete maintenance is best done in the warmer months immediately after the ravages of the winter (meaning spring) and the same broadly goes for laying concrete surfaces for the first time. Nevertheless, sometimes the job just needs to be done in cold weather.
By mixing the concrete with hot water, you can ensure that it sets for at least some of the time at the optimal temperature. The water will of course cool down in time, but this is a problem you can quite simply get around. Providing the heat yourself is the best way to ensure that the concrete sets properly. Heaters and covers designed for precisely this use are actually pretty standard products within the industry.
Tips for Pouring Concrete in Warm Weather
If you are pouring concrete in the warm weather, then the advice involves planning and being selective about when you pour. You should avoid pouring the concrete at the hottest point of the day and ensure that there is shade over the setting concrete. For the hottest days, you can try to avoid these altogether or look into special mix concrete designed for hot weather.
Ultimately, the best practice is to lay or repair concrete paving at the optimal time and to avoid temperature extremes. Nonetheless, when the job needs to be done, there is always something you can do.