Freezing in Concrete Walls

Pouring Concrete

• Concrete walls are most susceptible to damage from freezing and thawing after they are poured. If the concrete is allowed to freeze during the day after it is poured it can lose up to 50 percent of its strength. The amount of time required for concrete to set is highly dependent on several factors including the outside temperature, the type of concrete used, the concrete's mixture ratios and the desired strength. Concrete gains a significant portion of its strength during the month after it is poured. Although it is not usually necessary to protect concrete from freezing for more than a week, it is usually more economical to pour concrete in warm weather.

Preventative Measures

• If you pour concrete during cold weather, you can protect it using a layer of straw bales or an insulated thermal blanket. While the wall cures, it should maintain a surface temperature of 55 degrees Fahrenheit for the first three days. Avoid storing your concrete mix or any reinforcing members outside before pouring the wall to help prevent it from freezing and ensure a proper pour.

Existing Walls

• Concrete walls have a porous structure that absorbs water. If your walls are routinely exposed to water and allowed to freeze, the repeated expansion and contraction of the water inside the open spaces of the concrete will weaken it. The most effective method for preventing this type of damage to your walls is to apply a water sealant. This will prevent water from penetrating the interior spaces of the wall. In heated basements, you can also apply insulation to the exterior side of the wall to prevent it from freezing during the winter. Some common symptoms of freezing damage in concrete walls include cracking, gaps around the aggregate and chunks crumbling from the wall.

Considerations

• Concrete that has a high ratio of water to cement and aggregate is more susceptible to freezing damage than other types of concrete. Using air-entrained concrete will introduce small air bubbles throughout the wall that will provide space for freezing water to expand, preventing damage to your wall. The outside temperature directly affects the amount of time required for a new concrete wall to set and cure. If the concrete is allowed to drop below 20 degrees Fahrenheit, it will not set.