Cracks in Concrete Due to Temperature

The Freeze-Thaw Cycle

• Some cracks in concrete develop because of the cycles of freezing and thawing that occurs in cold climates. These cracks usually occur three or more years after the concrete is first poured. Water naturally accumulates around the base of the concrete structure and soaks in. When the freeze-thaw cycles of winter begin, the concrete can start cracking in these spots. Ensuring there is a good drainage system can help alleviate this problem.

Air Entrained Concrete

• Air entrained concrete is one way to help prevent cracks caused by temperature differences during the winter. This is done by intentionally causing small air bubbles to form when the concrete is being mixed. The air bubbles are produced by adding a chemical that contains a surfactant or type of detergent. According to the PCA, "the bubbles act to reduce or absorb stresses from freezing" and "contribute to workability by acting as a sort of lubricant for all the aggregates and large particles in a concrete mix."

Problem Solving

• There are several ways to reduce the size and chance of temperature-induced cracks in concrete from occurring. Using a good concrete mix but with a minimum amount of water is one way to solve this problem. Another is to reinforce the concrete with steel to reduce the size of the cracks. Contractors often install certain designated areas that are called "intentional weak spots" where the eventual cracks can be seen and waterproofed. Ensuring that temperatures do not fluctuate rapidly when the concrete is curing also helps to prevent concrete cracks from forming due to severe temperature changes.

Time for Concern

• It is wise to monitor any temperature-induced concrete crack. But according to PCA you should probably take action when a crack in the concrete becomes wider than a quarter of an inch or you notice water seeping through the concrete.