Let’s consider a circular column to demonstrate this phenomenon.
When the temperature rises, the concrete at the core heats up faster than the outer layers, leading to expansion. This expansion exerts pressure outwards, generating compressive stresses near the surface. If these stresses exceed the concrete’s tensile strength, radial cracks will form near the surface.
Conversely, when the temperature drops, the outer concrete cools rapidly to match the ambient temperature, while the core cools more slowly. This differential cooling results in the contraction of the inner concrete, inducing tensile strains. These strains can lead to the formation of cracks that run tangentially to the circular radius of the column.
Understanding this behavior is crucial in the design and construction of concrete structures. By anticipating and mitigating these thermal stresses, engineers can prevent cracking and ensure the structural integrity and longevity of concrete elements. This can be achieved through various measures, such as incorporating expansion joints, using appropriate reinforcement, and controlling the rate of concrete curing.