Red Seal Ironworker (Reinforcing) Practice Exam

In reinforced concrete, what is the purpose of tensioning?

1. To create decorative patterns in the structure

2. To pre-stress the concrete and counteract tension opening in the structure

3. To ensure uniformity in the concrete mix

4. To delay the setting of the concrete

The correct answer is: To pre-stress the concrete and counteract tension opening in the structure

The purpose of tensioning in reinforced concrete is to pre-stress the concrete and counteract tension opening or cracking that may occur in the structure due to external loads. When concrete is subjected to tensile forces, it can lose its structural integrity because concrete is inherently weak in tension. By tensioning the reinforcing steel bars (or tendons) before or during the pouring of the concrete, the compressive forces introduced by the tensioned steel counterbalance these tensile forces when the structure is in use. This pre-stressing effectively allows the concrete to carry greater loads without cracking, improves the overall durability, and increases the lifespan of the concrete structure. The other options focus on aspects that do not relate to the fundamental engineering principle of tensioning. Creating decorative patterns does not reinforce structural integrity, ensuring uniformity in the concrete mix pertains to material properties rather than stress management, and delaying the setting of concrete does not feature in the tensioning process, as it is concerned with managing stresses in the hardened concrete.