What is the primary reason for replacing marble cladding, as seen in the Aon Center?

The primary reason for replacing marble cladding in structures such as the Aon Center is due to the degradation of the material. Marble, while a beautiful and historically significant choice for exterior cladding, is susceptible to weathering and environmental factors. Over time, exposure to elements like rain, sunlight, and pollution can lead to physical deterioration, including cracking, staining, and erosion. This degradation can compromise not only the appearance of the building but also its structural integrity.

In contrast, while cost reduction, aesthetic enhancement, and compliance with safety regulations are important aspects of any architectural decision, they are not the primary driving force behind the need to replace cladding that has degraded. This replacement often involves restoring the building to its original aesthetic while ensuring that it meets the standards required for longevity and safety.