Oh, UNBONDED! Sorry.
PTI 6.4.2 says: Generally, the free stressing length should remain unbonded after stressing, except to satisfy specific structural requirements. PTI C6.4.2 says: Unbonded free stressing lengths allow a more flexible performance of the anchor and the averaging of structure strains resulting in less load shange in individual anchors. Typically, fully bonded and partially bonded free lengths are only applicable in massive concrete structures (dams, diaphragm wall t panels, etc).
PTI 6.8 says: The free stressing length for rock anchors and soil anchors shall not be less than 4.5 m (15 ft) for strand tendons and 3.0 m (10 ft) for bar tendons. PTI C6.8 says: The minimum stressing length recommended is to prevent significant subsequent reductions in transfer load due to seating losses. Shims placed below the wedge plate can compensate for these losses. For more information, the designer should contact the anchor tendon manufacturer.
There is even more about the free stressing (unbonded) length in PTI 6.8.