Red Seal Ironworker (Reinforcing) Practice Exam

What role does tensioning play in pre-stressed concrete?

1. It allows for a continuous flow of concrete

2. It helps to balance internal forces within the structure

3. It simply reduces the material costs

4. It improves the visual appearance of concrete

The correct answer is: It helps to balance internal forces within the structure

Tensioning in pre-stressed concrete is essential for balancing internal forces within the structure. By applying tension to the steel tendons before the concrete is cast, the resulting compressive forces counteract the tensile stresses that occur when the concrete is in use. This process helps prevent cracking and enhances the overall durability and performance of the concrete member under load. When the tendons are tensioned, they create an initial compressive stress in the concrete, which is crucial because concrete is naturally strong in compression but weak in tension. This pre-emptive measure of tensioning effectively ensures that the internal forces are optimized, enabling the structure to withstand external loads more effectively and extending its service life. While factors such as reducing material costs and improving visual appearance are relevant aspects of construction materials, they do not capture the primary purpose and significance of tensioning in pre-stressed concrete, which is fundamentally about managing and balancing internal forces to ensure structural integrity.