How Does Heat Affect Precast Concrete?

Will concrete crack under extreme heat? That’s a question often explored in our industry, and the answer is not a simple “yes” or “no.” With most of our facilities in Florida and Texas, Permacast Precast Concrete Fencing & Walls has a vested interest in answering this question, making us a bit of an expert on the subject. The understanding of thermodynamics and their impact on building materials, particularly concrete, is important to the successful production of long-lasting concrete. Here are some important facts to consider as you think about your next building project and which concrete you’ll use. 

Cracking

There are three main points at which concrete typically cracks: while drying, with quick changes in ambient temperatures, and when low humidity is present. Concrete can crack during the drying process if the aggregate shrinks due to low water to concrete (w/c) ratio. This ratio can be altered when water is added to the mix without adjusting the amount of cementitious material. Thermal cracking occurs when the ambient (surrounding) temperature changes quickly during the drying process. It can also happen with an increase in the concrete temperature in larger members, which is something we watch carefully with precast concrete. Finally, low humidity combined with high winds in arid climates can lead to accelerated evaporation during the drying process. This leads to cracking, as well, but is not much of an issue in Texas and Florida, where humidity is relatively high, even in cooler months. 

Hydration

Controlling water temperature can be a major factor in reducing cracking in concrete. Adding ice chips to the water before mixing, using steam during the curing process, and misting during warm weather all work to control the amount of hydration during the production process. Keeping water cool with ice chips allows for better control over the temperatures at which the aggregate is mixed. Steaming the finished product behind curtains during the drying process keeps the product moist and the curing temperatures up during the curing process. Misting the forms and reinforcement just before placing them can help prevent unwanted temperature increases while cooling the products on site. All of the steps taken together result in long-lasting precast concrete with a high resistance to cracking.  

Ambient Heat

In Florida and Texas, outdoor temperatures are a very real factor in any construction project. By maintaining consistent temperatures and water values throughout the mixing, casting, finishing and curing processes, our precast concrete is prepared to stand up to any weather conditions, enduring sultry summer heat beautifully for years to come. 

Since the process of creating precast concrete is controlled from start to finish, the possibility of our finished products is reduced greatly. This gives you confidence to build with Permacast Precast Concrete Fencing & Walls, knowing the reliability and durability of our products is second to none. Talk to us about your next project at one of our Lunch & Learn sessions and find out more about how our products will suit your next project’s needs.