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Pouring Concrete in Cold Weather: Key Considerations

Pouring concrete in cold weather may cause problems with concrete strength and durability. In this article, we will discuss with you what kind of precautions can be taken when pouring concrete in cold weather, and all of the factors that must be taken into consideration.

Six Precautions to Take Prior to Pouring Concrete in Cold Weather

In order to prevent concrete prepared and placed in cold weather from being negatively affected by the low temperatures, special precautions can be taken prior to pouring the concrete.

  1. It is important to avoid, as much as possible, pouring concrete in weather conditions that pose a risk of freezing.
  2. Production equipment (chemical additives and water pipes, bunker lids, etc.) should be checked before closing the plant for the night and the necessary precautions should be taken to prevent freezing (emptying any remaining material from equipment, heating during the night, etc.).
  3. If necessary, the raw materials should be heated to prevent the initial temperature of the concrete from dropping to the freezing point.

Figure 1. Heating System and Insulation for the Aggregate Stock Area

Image 2. Water Tank Insulation and Heating System

  1. The bulk aggregate kept in the stokehold should be mixed up prior to production and any potential ice on the surface must be thawed. 
  2. The customer must definitely be warned about the hazards of pouring concrete in cold weather. In particular, you might recommend pouring concrete that is one class higher than that called for in the project specifications (lower water/cement ratio).
  3. All of the construction equipment at the site where the concrete will be poured must be checked to ensure that the temperature of the equipment is above freezing. Before the concrete is placed, the surface of all of the forms that will come into contact with concrete should be checked.  If there is snow or ice, it must be removed. Care should be taken to ensure that the temperature difference between the concrete and the forms into which it will be placed is not too great. Wooden forms are preferable to metal ones.

Eight Precautions to Take When Pouring Concrete in Cold Weather

In order to prevent concrete prepared and placed in cold weather from being negatively affected by the low temperatures, special precautions are required.

  1. Cement with high initial strength and hydration heat should be used. The highest possible cement dosage and lowest water/cement ratio should be selected. The use of mineral additives should be minimized, and laboratory result should be taken into consideration. 
  2. Additives that accelerate the setting time of fresh concrete and lower the freezing point of water should be used. Chemicals that accelerate the setting time for concrete include CaCl2, calcium nitrite, sodium thiocyanate, potassium carbonate and calcium formate. When these chemicals are dissolved in water, they lower the freezing point of the water. Laboratory controls must be conducted. 
  3. If you anticipate the concrete being exposed to water or to a freeze-thaw situation, air entrainment chemical additives can be used.
  4. The concrete mixing time can be increased during production to increase freeze resistance. 
  5. The concrete should be transported to the site with a transmixer as soon as possible. An average temperature loss of 3°C occurs for every 100 meters the concrete is pumped through a hose.
  6. Thermal insulation should be used to keep the heat created as a result of cement hydration inside the concrete, or suitable insulation should be used on the outside of the forms. Exposed concrete surfaces should be insulated by covering with materials such as sawdust, straw, fiberglass or foam board. The forms should be left on longer than normal.
insulated-forms-v2

Figure 3. Insulated Forms

protecting-the-job-site-from-external-conditions-with-a-membrane

Figure 4. Protecting the Job Site from External Conditions with a Membrane

insulating-the-job-site-with-nylon-sheeting

Figure 5. Insulating the Job Site with Nylon Sheeting

  1. The temperature of the fresh concrete should be measured regularly and controlled. 
  2. If the temperature of the area where fresh concrete is poured falls below +5 °C for 24 hours, it should be protected from freezing for 48 hours and if it is below +5 °C for more than one day, then it should be protected for 72 hours. This is especially important on industrial floor jobs with a large surface area.
tunnel-forms-and-insulation-of-concrete

Figure 6. Tunnel Forms and Insulation of Concrete 

Why You Must be Careful When Pouring Concrete in Cold Weather?

In this article, we have gone into some detail about the measures to be taken before and after pouring concrete in cold weather. We have highlighted the importance of these measures to prevent cold weather from having a negative effect on concrete quality and strength. If the measures outlined above are taken, your concrete pour will be durable, strong and last many years. 

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