What is the primary purpose of control joints in concrete masonry walls?

The primary purpose of control joints in concrete masonry walls is to accommodate shrinkage during drying. As concrete dries, it undergoes a process called shrinkage, which can lead to cracking if there is no provision to relieve the stresses that develop. Control joints are strategically placed in the masonry to divide the wall into sections, allowing for movement without damaging the structure.

These joints serve to absorb the expansion and contraction that naturally occurs due to temperature fluctuations and moisture changes, helping to maintain the integrity and aesthetic of the wall. This design consideration ensures that the wall performs well both structurally and visually over time.