What process occurs in a sidewalk when the temperature decreases?

When the temperature decreases, the materials in a sidewalk, typically concrete, undergo thermal contraction. This means that the concrete shrinks as it cools down, which can lead to the formation of cracks or gaps if the contraction is significant. Additionally, if moisture is present, it can freeze in these cracks, further expanding and potentially causing more damage. Overall, the structural integrity of the sidewalk may be compromised due to these temperature-induced changes.