Corrosion protection for Rock Anchors 2

[suqlainUK]

The design for a basment under 5m head of water called for "ground anchors" to resist the buoyancy forces. The contractor has proposed "tension piles" using 40mm GEWI bar. The codes require "double corrosion" protection for ground anchors but are not so stringent for tension piles or soil nails? Although in this case the proposed single tension pile (no initial prestress proposed) has been galvanised to give nominal corrosion protection. The ground water contains no contaminanates.
1. Any expert views on the corrosion protection aspects? 2. Or when a ground anchor is not a ground anchor but a tension pile or soil nail?

 

[Qshake]

Will the pile, nails, or rock anchor be exposed to the air? If not then you can safely eliminate the formation of oxides as it requires oxygen for the reaction to take place.

Rock anchors aren't generally as large as piles and nails and perhaps there has been some sacrificial thickness incorporated into the design of those elements.

 

[phillyfrank]

In North America, rock reinforcement bars are "double protected" by having an epoxy coating, and then using polyester resin or portland cement grout as the anchoring media or "glue." I wrote a paper 2 years ago pulling together everything I could find on rock reinforcement corrosion and longevity. It is in the 2000 Ground Control in Mining Conference from West Virginia University in Morgantown, WV, USA. If the proceedings are not available to you, please contact me and I can fax or snail mail a copy of the paper "Rock Reinforcement Longevity." frankatagapito@aol.com