Certified Facility Manager (CFM) Practice Exam

Why are joints in concrete used?

1. To increase the surface area of the slab

2. To give more decorative options in concrete surfaces

3. To control the location of cracks

4. To facilitate water drainage

The correct answer is: To control the location of cracks

Joints in concrete serve a critical purpose in managing the behavior of concrete as it expands, contracts, and undergoes setting and curing. Specifically, they are strategically placed to control the location of cracks. As concrete cures, it inherently experiences shrinkage, which can lead to crack formation if there is no way to manage the stresses that develop. By incorporating joints, facility managers can predict and guide the areas where cracks are more likely to occur, thereby minimizing the potential for unsightly or structural damage. This approach allows for better durability and longevity of concrete surfaces. The design of these joints ensures that any cracking occurs along predetermined lines, thus preventing random and possibly more damaging cracks from forming throughout the slab. While other options might touch on aspects related to aesthetics, drainage, or surface area, they do not address the fundamental purpose of joints in mitigating cracking and ensuring structural integrity in concrete applications.