How are unbonded tendon fabrication procedures primarily initiated?

Unbonded tendon fabrication procedures are primarily initiated by coating the strand through melting. This process involves applying a protective coating to the tendon strands, which serves multiple purposes. The melting process allows the coating material, often a type of polymer, to adhere to the surface of the tendon, providing effective corrosion resistance and improving the durability of the tendon when used in various construction applications. The coating also helps in minimizing friction between the tendon and the surrounding materials, which is critical in maintaining the performance characteristics of unbonded post-tensioned tendons.

The other methods listed, such as casting or setting the tendon in a mold, do not reflect the primary initiation of the unbonded tendon fabrication procedures. While applying a corrosion-resistant sealant could be part of the overall process, it is not the initial step that defines the unbonded approach to tendon fabrication.