Is prestressed concrete considered a passive or active form of reinforcing concrete?

• A. Active
• B. Passive
• C. Neither
• D. Both

Answer: (B)

Prestressed concrete is considered a passive form of reinforcing concrete because it involves the application of pre-compressive forces to the concrete before it is subjected to any service loads. This technique enhances the concrete's ability to resist tensile stresses that develop during service, effectively overcoming its natural weakness in tension. The prestressing is performed through methods like pre-tensioning or post-tensioning, where tendons or cables are tightened to create this beneficial compressive state.

In contrast, active reinforcement would involve the continuous or dynamical application of forces or corrective measures after the initial placement and curing of the concrete, which is not the case with prestressing. Therefore, since prestressed concrete relies on the initial introduction of compressive forces to improve performance and does not require further adjustments during its use, it is classified as a passive reinforcement technique.