How Cold is Too Cold to Pour Concrete?

What Temperature is Too Cold to Pour Concrete?

Experts agree that the best temperature to pour concrete is between 50-60 °F. The necessary chemical reactions that set and strengthen concrete slow significantly below 50 °F and are almost non-existent below 40 °F. Even when daytime temperatures are within the satisfactory range, winter concrete setting creates risks that could result in weak, inadequate concrete. If nighttime temperatures are below freezing, the water in the concrete will freeze and expand, causing cracks. Additionally, if temperatures reach below 40 °F (but not freezing) during set time, concrete will take much longer to reach required strength. However, if the correct measures are taken, concrete can still be successfully placed during even the coldest months of the year.

Things to Consider with Cold Weather Concreting

Before embarking on a cold weather concrete project, it’s important to determine any special strength requirements or considerations. This will help as you schedule your pouring and determine which strategies you will use to keep your surroundings and materials warm. The predominant challenge you will face during a winter concrete project is ensuring that the concrete sets before it is exposed to freezing temperatures. You might take the following suggestions into consideration as you plan your upcoming project:

  • Use heaters to thaw frozen ground, snow or ice.
  • Use hot water to mix cement.
  • Keep dry materials in a dry, warm location.
  • Use products designed to set quickly. During cold weather, these products will not set as quickly as the instructions may indicate, but will set faster than conventional materials.
  • Use additives that accelerate set time. Use caution; if additives contain calcium chloride, any rebar or metal wire mesh in concrete will rust and cause concrete to crack.
  • Use extra cement (typically 100 lb/ cubic yard) to make the reaction hotter and cause concrete to hydrate more rapidly.
  • Remember that you still need to wait for bleed water to evaporate. Incorporating the water into the surface during finishing will weaken the surface. Bleeding starts later and takes longer during cold weather; you can use squeegees or a vacuum to remove water quickly.
  • Wait until concrete has reached desired strength to remove any framework. If the framework is removed too early, the concrete will be damaged and the surface could collapse.

Maintaining Ideal Temperature

After implementing the above suggestions, It’s important to consider how you will keep concrete at the correct temperature during the curing process. Concrete must maintain a temperature above 50 °F for approximately 48 hours for the correct chemical reactions to take place. Two popular options used during cold weather concrete curing are heated enclosures and insulated blankets. If using an enclosure, ensure that the structure is both wind and waterproof. Additionally, ensure that there is proper ventilation for the space heater. Heaters cause an increase in carbon dioxide that could cause carbonation in the surface of the concrete.

Powerblanket Concrete Blankets

Powerblanket® concrete blankets are an extremely effective option for attaining and maintaining the correct temperatures for concrete pouring and setting. Powerblanket® concrete blankets can be used to thaw ground before pouring concrete and again after finishing to keep concrete from freezing. Utilizing Powerblanket® concrete blankets will ensure that concrete is kept at the correct temperature for the necessary reactions to happen quickly and the desired strength to be reached.

What Temperature is Too Cold to Pour Concrete?

What Temperature is Too Cold to Pour Concrete?
What Temperature is Too Cold to Pour Concrete?

What Temperature is Too Cold to Pour Concrete?

Experts agree that the best temperature to pour concrete is between 50-60 °F. The necessary chemical reactions that set and strengthen concrete slow significantly below 50 °F and are almost non-existent below 40 °F. Even when daytime temperatures are within the satisfactory range, winter concrete setting creates risks that could result in weak, inadequate concrete. If nighttime temperatures are below freezing, the water in the concrete will freeze and expand, causing cracks. Additionally, if temperatures reach below 40 °F (but not freezing) during set time, concrete will take much longer to reach required strength. However, if the correct measures are taken, concrete can still be successfully placed during even the coldest months of the year.

Before embarking on a cold weather concrete project, it’s important to determine any special strength requirements or considerations. This will help as you schedule your pouring and determine which strategies you will use to keep your surroundings and materials warm. The predominant challenge you will face during a winter concrete project is ensuring that the concrete sets before it is exposed to freezing temperatures. You might take the following suggestions into consideration as you plan your upcoming project:

  • Use heaters to thaw frozen ground, snow or ice.
  • Use hot water to mix cement.
  • Keep dry materials in a dry, warm location.
  • Use products designed to set quickly. During cold weather, these products will not set as quickly as the instructions may indicate, but will set faster than conventional materials.
  • Use additives that accelerate set time. Use caution; if additives contain calcium chloride, any rebar or metal wire mesh in concrete will rust and cause concrete to crack.
  • Use extra cement (typically 100 lb/ cubic yard) to make the reaction hotter and cause concrete to hydrate more rapidly.
  • Remember that you still need to wait for bleed water to evaporate. Incorporating the water into the surface during finishing will weaken the surface. Bleeding starts later and takes longer during cold weather; you can use squeegees or a vacuum to remove water quickly.
  • Wait until concrete has reached desired strength to remove any framework. If the framework is removed too early, the concrete will be damaged and the surface could collapse.

After implementing the above suggestions, It’s important to consider how you will keep concrete at the correct temperature during the curing process. Concrete must maintain a temperature above 50 °F for approximately 48 hours for the correct chemical reactions to take place. Two popular options used during cold weather concrete curing are heated enclosures and insulated blankets. If using an enclosure, ensure that the structure is both wind and waterproof. Additionally, ensure that there is proper ventilation for the space heater. Heaters cause an increase in carbon dioxide that could cause carbonation in the surface of the concrete.

Powerblanket® concrete blankets are an extremely effective option for attaining and maintaining the correct temperatures for concrete pouring and setting. Powerblanket® concrete blankets can be used to thaw ground before pouring concrete and again after finishing to keep concrete from freezing. Utilizing Powerblanket concrete blankets will ensure that concrete is kept at the correct temperature for the necessary reactions to happen quickly and the desired strength to be reached. With Powerblanket, it’s almost never too cold to pour concrete!

Compressed Gas Sizes

Powerblanket Curing Blankets at the Statue of Liberty

Powerblanket® Goes to the Statue of Liberty

Reilly Construction out of Wrightstown, NJ won a bid from the U. S. Department of the Interior, National Parks to replace the roof of The Great Hall Statue of Liberty National Monument.  The Great Hall, which now houses the Ellis Island Immigration Museum, is considered one of the most symbolically important structures in American history. The Great Hall-Ellis Island was proclaimed a part of Statue of Liberty National Monument and is listed on the National Register of Historic Places.  Reilly nee
ded extra heat in the form of curing blankets to make this job happen.

 

The project involved removal of the existing inverted roof membrane assembly (IRMA) and replacement with a new multi-ply modified bitumen roofing system over a complicated tapered insulation deck assembly, approx. 60,000 Sq. Ft. The project also included the replacement of custom fabricated copper flashings and accessories throughout and the installation of a lighting protection system. Reilly worked with the NYS Historic Preservation Office (SHPO) to coordinate all the work.

 

Challenges Faced by Reilly

  •     Cold winter weather and high winds at this waterfront facility
  •     Working safely around thousands of tourists visiting this historic landmark daily
  •    Implementing various overhead protection plans at this historic landmark daily
  •    Mobilizing materials and equipment on a small island
  •    Limited laydown and staging areas
  •    Coordinating construction schedule with NPS & U.S. Park Police for VIP visits
  •    Ensuring compliance with the NYS Historic Preservation Office (SHPO)
  •    Day & night work


Finding Powerblanket

Dan DeSantis, the Senior Project Manager for Reilly, found Powerblanket products online and left his contact information. Upon follow up, we discovered that Reilly needed a heating solution to cure the masonry block work at the proper temperature (~50°F/~10°C) during December in New York and with the added chill of the water. Reilly used five Powerblanket MD0520 concrete curing blankets for the application, and appreciated the increased temperature control.

A Cure for What Ails You

Powerblanket concrete curing blankets provide a manageable way to cure concrete effectively and confidently in the cold weather months. Even in warm weather, Powerblanket curing blankets increase production by rapidly curing with consistent, even heat.

Why Choose Powerblanket Concrete Curing Blankets?

  •    Cure concrete 2.8 times faster than conventional, insulated blankets
  •    Produce cold weather concreting strength of up to 3,925 psi in 72 hours
  •    Maintain moisture throughout hydrating process
  •    Easily installed and removed
  •    Prevent a freeze cycle
  •    Thaw ground and frost from job site prior to pour
  •    Reduce downtime & increase profitability
  •    Maintain ACI compliance for cold weather concreting