Nitrates in p.t. grout

[ajk1]

Does anyone know if nitrates are corrosive to post-tendioning strand and should be limited as to their concentration in grout for bonded tendons, or not? I used to think they were corrosive, but recent checks to various references on the internet seem to indicate that they are not.

Do cement standards limit nitrate concentration?

 

[PEinc]

PTI's Fifth Edition Post-Tensioning Manual,page 284, Section 4.6, Corosion Protection says, "Permanent anchors placed in environments where any one of these tests (for resistivity, pH, sulfides, chlorides, sulfates)indicates critical values, must be encapsulated over their full length. The presence of other corrosive elements, such as nitrates, rhodanides, etc., may also be critical for the anchor tendon and require its full encapsulation." No threshold limit is given for nitrates in this section. Check with a tendon manufacturer.

http://www.PeirceEngineering.com

 

[ajk1]

PEInc.

Thank you for this. I should have thought to look in the PTI Manual before posting; I believe I have the latest manual in the office. Still, this does seem to put it at odds with internet info. When I get into the office later this week, I will check with PTI to see if their current thinking remains as per the latest publication of the PTI Manual. Checking with the tendon supplier as you suggest is also a good idea. Thanks again.

 

[ajk1]

To PEInc.

My 6th edition of the Post-Tensioning Manual (2006) does not have a section 4.6.
I checked all the references in the index about Corrossion Protection and then scanned the text quickly and could not find anything like what you quote from thr earlier edition. Perhaps I have missed it, but it seems that they have taken it out. I will call PTI and check with them.