What is a common source of stress that leads to thermal cracking in concrete?

A common source of stress that leads to thermal cracking in concrete is temperature differentials. When concrete is placed, it undergoes a chemical reaction known as hydration, which generates heat. As the temperature rises, different parts of the concrete may expand at varying rates due to inconsistent heating. For instance, the surface may cool faster than the interior, causing tension stresses in the material as it tries to contract while the interior continues to expand slightly.

This phenomenon becomes particularly problematic in large pours or areas exposed to direct sunlight, where temperature differences can be pronounced. If the stresses induced by these temperature differentials exceed the tensile strength of the concrete, cracking occurs. Therefore, managing temperature throughout the curing process is essential to minimize the risk of thermal cracking, making it a key consideration in concrete design and placement.