Are all post-tensioned tendons required to be encapsulated?

[cliff234]

Can someone tell me if ACI 318-14 (or -19) requires the use of an encapsulated system for all unbonded PT construction for all slabs regardless of whether the slab is exposed to weather? We always use encapsulated tendons in garages; however, someone recently told me an encapsulated system is required for all PT construction. I can’t find this requirement anywhere. Thank you!

 

[bumbler]

Cliff,

I just ran across this the other day as well but haven't had time to look more into the actual requirement. I saw it in PTI Technical Note #18 at the following link: [URL unfurl="true"]https://www.post-tensioning.org/education/publications/faqstechnotes.aspx[/url]

See section "1-Introduction" for the relevant directive from PTI: "All unbonded single strand post-tensioning tendons used for structures designed in accordance with the Building Code Requirements for Structural Concrete (ACI 318) must be encapsulated, regardless of the exposure conditions." This is as far as my knowledge goes but it should give you a starting point.

 

[BAretired]

Yes, they all must be encapsulated. You could not stress them without encapsulation...too much friction, even with grease.

 

[OldDawgNewTricks]

ACI 318 references ACI 423.7 for unbonded tendon specifications. The commentary says: