Annex B
(informative)
Investigation testing of corrosion protection
This annex describes investigation methods for establishing the integrity of the corrosion protection of a prefabricated anchor encapsulation in a loaded or post-loaded condition. These tests are undertaken in a test frame. Figure B.1 shows the general arrangement of the test apparatus.
TEST A
This method involves the loading of an encapsulated tendon with the encapsulation unconfined.
The tendon, the encapsulation grout and the surrounding plastic duct(s) are subjected to loading conditions identical to those on a service anchor.
The anchor is loaded to the maximum load it will be subjected to during testing in situ.
The flexibility and crack resistance of the duct is observed externally during the loading of the anchor.
The tendon is subsequently unloaded to zero load.
A section of the outer plastic covering is removed and the tendon reloaded to the lock-off load in order to inspect the condition of the inner duct and to check the crack distribution and crack widths in the encapsulation grout.
TEST B
This method involves the loading of an encapsulated tendon in a confined and bonded state within a grouted split gunbarrel.
The loading condition simulates that applied to a service anchor.
The anchor is loaded to the maximum load it will be subjected to during testing in situ.
The tendon is unloaded to zero load.
The gunbarrel is split open and the gunbarrel grout removed from the outer plastic duct. The integrity of the outer plastic duct is then proved by inspection.
On removal of the outer duct either the inner duct is inspected or, in the absence of an inner duct, the distribution of the cracks in the encapsulated grout is measured.
The tendon extension under the applied service load divided by the number of cracks observed is an indication of the average width of crack in the grout under service loading condition.
Key
- 1 Inspection of inner duct or grout crack distribution/carck width observed/measured in a loaded (Test "A") or unloaded (Test "B") condition at various locations
- 2 Test frame
- 3 Anchor encapsulation
- 4 Bar or multi-strand system
- 5 Split gunbarrel
- 6 Grout
A Test "A" Unconfined condition
B Test "B" Confined condition
