North Carolina Building Contractor License Practice Exam

In what location should WWM be used when placing in a concrete slab?

1. On the top

2. In the middle

3. On the bottom

4. Near the edges

The correct answer is: In the middle

The correct approach for placing welded wire mesh (WWM) in a concrete slab is to position it in the middle of the slab. This placement is critical because it provides optimum tensile strength, helping the concrete resist cracking and load pressures. Since concrete is excellent in compression but weak in tension, situating the WWM within the core of the slab enhances its structural integrity by allowing the mesh to help control cracking that may occur due to tensile stresses. Additionally, placing the WWM in the middle ensures that it is adequately encased within the concrete, safeguarding it from corrosion and exposure, which could diminish its effectiveness over time. This strategic positioning complements the overall design of the slab and contributes to a durable and reliable foundation for various applications, from driveways to floors.