Post-tensioning involves stretching steel strands after concrete has been cast?

• A. False
• B. It does not involve tensioning
• C. It involves stretching before
• D. It involves stretching after

Answer: (D)

Post-tensioning introduces prestress after the concrete has been poured and has gained sufficient strength. Steel strands run through ducts in the concrete, are stretched with hydraulic jacks, and then anchored at the ends. This tension compresses the concrete, helping resist cracking and bending, which is why post-tensioned members can be thinner or span longer than non-prestressed ones. After tensioning, the tendons are often grouted to protect the steel and lock in the prestress. This is different from pretensioning, where the steel is stretched before casting. So the statement that post-tensioning involves stretching after casting is correct.