“Cure” for the Common Cold? The Challenges of Cold Weather Concreting
The Intermountain West can see some pretty gnarly winter weather. While this is good for our snowpack, it can make outdoor construction projects particularly difficult. Builders here don’t have the luxury of taking an entire season off, and instead, have found a range of workplace strategies and products that protect their materials, tools, and workers from cold weather.
Concrete is one material that is especially vulnerable to the cold – and by cold, we mean any temperature less than a relatively mild 50 degrees. If builders can’t pour concrete until they’re assured of several weeks of warm weather, then just about all projects would be severely delayed. Almost everything, from bridges, to foundations, to parking structures, to even the largest contemporary artwork ever built, relies on concrete. In fact, concrete is often cited as second only to water as the world’s most-consumed resource.
So why is concrete so sensitive to temperature? The hard concrete pads we walk, build, and drive on are all formed when a mix of sand and stone aggregate is bound by a chemical reaction between cement and water. Called “curing,” this reaction can take several weeks to complete, and it is during this critical period that the concrete attains the appropriate levels of hardness and strength needed for a specific application.
Controlling temperature and moisture is fundamental to the proper curing of concrete, and the two are very much interconnected. Below 50 degrees, water evaporation slows and the chemical hardening process takes much longer, which can result in a weaker, uneven product. Weather below freezing can cause the water in concrete to freeze and expand, which leads to cracking.
Not to be deterred, builders and manufacturers have developed a range of strategies and products that ensure successful winter concrete work. These include:
- Using ground-warming heated blankets to thaw the subgrade and ensure concrete isn’t poured on a cold surface
- Building with insulated forms that don’t transfer cold to newly poured concrete
- Including additives that speed up curing time and mixing concrete with heated water
- Covering poured concrete with moisture-impervious insulating blankets, heated blankets, and other insulation materials, that allow for evaporation and speed-up curing time
- Building and heating temporary enclosures around the poured concrete
- Installing portable hydronic heating systems for particularly large pours
The American Concrete Institute, which has strict specifications for curing concrete in cold weather, notes that despite these challenges, there can be an advantage to placing concrete in the winter. In their Guide to Cold Weather Concreting, they state:
“Concrete placed during cold weather, protected against freezing, and properly cured for a sufficient length of time, has the potential to develop higher ultimate strength … and greater durability than concrete placed at higher temperatures.”
So, while there isn’t yet a cure for the common cold, there are many ways to ensure the successful curing of concrete in the cold. And that’s good news for all of us, who every day rely on concrete structures for our shelter, our transportation, and our workplaces.
From cold-weather personal protection to insulated concrete blankets, Industrial Supply Company offers a wide scope of products that help the construction industry thrive during the harsh winter months.