What is the minimum waiting period for tensioning after the last concrete has been placed if testing is not being performed?

The minimum waiting period for tensioning after the last concrete has been placed, when testing is not being performed, is 10 days. This time frame is established to allow the concrete to reach sufficient strength and hydration, which is critical for achieving optimal performance and durability of the tensioned elements.

The early strength gains in concrete are significant in the first week after placement, and by waiting for this 10-day period, the concrete should have developed adequate compressive strength to safely accommodate the stresses induced during tensioning. Adhering to this waiting period helps ensure structural integrity and minimizes the risk of cracking or other detrimental effects resulting from premature tensioning.

Other options, such as 7 days, 14 days, or 28 days, do not align with the standard practice that balances the need for strength with the practicality of the construction schedule. Seven days might be too early, potentially leading to mechanical failures, while 14 and 28 days exceed the typical requirements for tensioning, causing unnecessary delays in the construction timeline.