North Carolina General Contractors Practice Exam

What need does the design of control joints in CMU address?

1. Expansion and contraction

2. Aesthetic considerations

3. Weight reduction

4. Utility conduits

The correct answer is: Expansion and contraction

The design of control joints in Concrete Masonry Units (CMU) primarily addresses the need for managing expansion and contraction that occurs in masonry walls. As temperature changes and moisture levels fluctuate, materials can expand and contract, potentially leading to cracking if these movements are not properly accommodated. Control joints provide the necessary space for this movement and help to minimize structural stress, allowing for natural expansion and contraction without compromising the integrity or aesthetics of the wall. While aesthetics, weight reduction, and utility conduits are important factors in building design and construction, they do not directly relate to the critical function of control joints in handling thermal and moisture-induced movement in masonry structures. The main purpose of control joints is to ensure that any potential stress resulting from these forces is managed effectively, preserving the overall longevity and durability of the masonry system.