Tips for Pouring Concrete in Winter

When it comes to pouring concrete in winter, weather can pose significant challenges. Concrete sets best at 50-60°F; pouring concrete in winter means the ambient temperature will likely fall well below this range. Fortunately, there are steps you can take to effectively tackle cold weather concrete curing.

Concrete Pouring Temperature Limits

As mentioned above, concrete prefers a mild temperature between around 50 and 60°F to set. Below this, the exothermic reactions that cause wet cement to transform into strong concrete will slow significantly. This could mean long delays in work while you wait for concrete to set and strengthen before continuing with a project. Additionally, If concrete reaches freezing temperatures during the setting process, the water in the cement mix will freeze and expand. This will cause concrete to become weak, brittle and even flaky when it sets.

 

Successfully Pouring Concrete in Winter

Fortunately, strategies can be implemented to increase the temperature of cement mixtures. Here are some tricks you can use to keep the cement flowing all winter long:

  • Use heaters or heated blankets to thaw surfaces where concrete will be poured. Pouring concrete on frozen ground will quickly cool concrete well below ideal temperatures. Using a heater to prep surfaces will prevent too-quick cooling or freezing and help keep the necessary reactions going.
  • Mix cement using hot water to help increase the temperature of the concrete.
  • Store materials in a warm location.
  • Use quick-set cement; during cold weather. It may set more slowly than the instructions indicate, but will still harden more quickly than traditional cement mix.
  • Mix in additives that accelerate set time.
  • Use extra cement (typically 100 lb/ cubic yard) to make the reaction hotter and cause concrete to hydrate more rapidly.
  • Utilize squeegees or a vacuum to remove bleed water that has a difficult time evaporating during colder weather.

Cold Weather Concrete Curing

After the concrete has been poured, it needs to be kept at the correct temperature to cure. Most importantly, it needs to be kept from freezing. Ideal temperatures (50-60°F) should be maintained for about 48 hours for the concrete to reach optimal strength as it sets. This can be tricky during the winter; even if temperatures are optimal during the day, they can plummet at nighttime. Maintaining warmer temperature will require some sort of external heat source. One option is a heated enclosure. These are effective but can be time-consuming to install. If you choose to use an enclosure, be aware that excess carbon dioxide from the heater can cause bubbling in the surface of concrete. This can typically be avoided with proper ventilation.

Concrete Blankets

Another option for temperature maintenance during cold weather concrete setting is concrete blankets. Concrete blankets can be used to thaw ground before pouring concrete and again after finishing to keep concrete from freezing. They are easy to install and transport and require only an outlet to use. This means no time wasted setting up complex heating mechanisms. If you’re interested in minimizing downtime involved pouring concrete in winter, these blankets are an excellent heating option to look into.

Powerblanket at the World of Concrete—A Demo in Concrete Curing

Earlier this month, Powerblanket attended the 2015 edition of the World of Concrete at the Las Vegas Convention Center. This year’s exhibition attracted 55,779 registered professionals. In addition, the event drew in 1,459 companies exhibiting their products and services. For Powerblanket and its concrete curing demo, the event proved to be a great way to engage with those in need of the company’s products.

 

Powerblanket at the World of Concrete—A Demo in Concrete Curing

Powerblanket and the World of Concrete

For Powerblanket, this year’s World of Concrete was an exciting investment of company time and resources. Powerblanket ran a concrete curing demo to demonstrate the effectiveness of Powerblanket® curing blankets on the set times and structural integrity of concrete pours. Those who were present were able to witness for themselves how much efficiency the curing blankets added to the curing process. Not only were the blankets able to cure the concrete nearly three times as fast, but they were also able to increase the strength of the concrete by 50%.

The slab used for the demonstration was 8” thick with a mix design that was formulated to provide a minimal PSI of 4,000 in only two days.  The slab was poured two days prior to the demonstration, and for the purposes of the demonstration, one portion remained unheated while the other section was covered in an MD series Powerblanket® curing blanket. At the beginning of the demonstration, the unheated portion of the concrete measured close to the 4,000 PSI that was required for the minimal target. Then the Powerblanket was added, and the portion of the slab that was heated by the Powerblanket MD Series concrete curing blanket measured a consistent 6,000 PSI after only 16 hours in place. That’s a PSI strength increase of 50% over the unheated portion of the concrete slab.

Powerblanket® curing blankets allow for such efficiency through the company’s patented technological approach to concrete curing and many other heating solutions. Not only do Powerblanket® curing blankets insulate the chemical reactions responsible for concrete heat exchange, but they also add heat to the equation—making them far more efficient than the common curing blanket.  Through the Powerblanket design, electrical heat is evenly distributed through the entire application, allowing for quicker set times and stronger concrete.

“Seeing people’s reactions to the demonstration was exciting,” said Ryan Jensen, Marketing Director for Powerblanket. “It was clear that everyone was impressed with the outcome.”

As a result, Powerblanket has engaged with more customers in an industry they already heavily serve.

 

Learn More

Can Electrically Heated Concrete Blankets be Used for Other Purposes?

How Do Heated Concrete Blankets Help Cure ConcreteYes. Electrically heated concrete blankets serve more than one purpose, especially in flatwork / concrete and general construction. Examples include:

It may be more appropriate to refer to these types of products as “heating solutions” instead of “blankets” to not confuse them with the common insulating blankets. These do not generate any heat themselves and rely on other sources of heat to make them a viable option.

3 things to look for in an electrically heated concrete blanket that can be used for other purposes:

  1. A product that generates heat but also distributes the heat evenly and efficiently
  2. A product that provides the right insulation so the heat generated is not lost
  3. A solution provider that supplies custom electrically heated blankets so your problem is solved

Tags: concrete blankets, electric concrete blankets