What is an important physical change to monitor in masonry after a fire?

Monitoring cracking and surface spalling in masonry after a fire is crucial for several reasons. High temperatures can cause the masonry materials to expand and contract, leading to physical distress. As the fire subsides and the materials cool, differential cooling rates can lead to cracking; this is particularly concerning in masonry structures because it can compromise their structural integrity.

Surface spalling occurs when the outer layer of the masonry material breaks off, which can further weaken the structure and expose underlying materials to the elements, increasing the risk of moisture intrusion and further degradation. Identifying these changes early on is essential for assessing the safety and stability of the structure and for determining necessary repairs or reinforcements to ensure it can continue to perform its intended function safely.

While other factors like color change, moisture content, and weight increase can provide some information about the condition of masonry after a fire, they do not directly indicate damage in the same way that cracking and spalling do. Monitoring these physical changes is fundamental to effective post-fire assessments in masonry construction.