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Re: Subject: Concrete Deck Tendon Repair

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Sharon,

There is a whole industry devoted to the repair and maintenance
of parking structures, PT or conventional reinforced.  Up here in
snow country, the chlorides from the snow melt on the roads can
ruin a parking deck in as little as 15-20 years.  You might try
contacting a rep from Sika.  I believe 2M is another company to try.

Dan Goodrich, P.E.
Provo, Utah


----- Original Message -----
From: <sharonb(--nospam--at)slarchitects.com>
To: <seaint(--nospam--at)seaint.org>
Sent: Tuesday, June 05, 2001 9:32 AM
Subject: RE: Subject: Concrete Deck Tendon Repair


> Thank you.  Your response is very thorough.
>
> I have done the walk-through visual investigation of all 6 levels of the
> garage including soffits, verticals and decks as well a chain drag to find
> the hollow areas in the decks.
>
> On the second level, where this occurs, there are nine exposed tendons.
> They are above one beam (perpendicular to the beam) and range from 12"
long
> to 21" long.  Two of the nine sheaths are damaged.
>
> I'm sure the defect was caused because of thin concrete coverage at the
high
> level of the tendons and the high traffic volume as most of the vehicles
> that use this garage pass over this area.
>
> Will you please explain what cracks you mean when you say "grease leaks
> through cracks."
>
> I appreciate your input.
>
> Sharon Robertson Bonds, PE
> Salerno/Livingston Architects
> 363 Fifth Avenue, Third Floor
> San Diego, California  92101
> (619) 234-7471
>
> -----Original Message-----
> From: Mark Geoghegan [SMTP:mgeoghegan(--nospam--at)structural-tech.com]
> Sent: Tuesday, June 05, 2001 5:36 AM
> To: Seaint
> Subject: Subject: Concrete Deck Tendon Repair
>
> sharon,
>
> a good technical and practical reference is the International
> Concrete
> Repair Institute (www.irci.org). they are about to release a guide
> specification on the repair of unbonded PT tendons.
>
> depending on the age of the parking garage will determine the type
> of
> sheathing used, and also the possible extent of damage. could be
> paper-wrap
> or plastic, push-thru, heat-sealed, or extruded. this will also have
> an
> effect on the repair that is undertaken.
>
> it appears that you can visually see the tendon (strand and grease,
> inside
> the sheath), so this could indicate that the tendon has failed
> (corrosion?)
> at some other location, released its tension, and erupted at this
> point. OR
> it may just be localized damage and corrosion is not the cause. you
> need
> more investigation.
>
> an investigation should be undertaken and begin with a review of the
> structural drawings and PT shop drawings, and a walk-through of the
> entire
> structure. during this initial visual and tactile investigation note
> any PT
> strand erupting, slab spalls, leaking joints, grease leaks through
> cracks,
> evidence of previous repairs, grout pockets loose etc.
>
> if this initial investigation reveals corrosion more investigation
> is
> prudent to determine more accurately the severity of the damage etc.
>
> any repairs should involve the owner, engineer and contractor. the
> repair of
> unbonded PT is specialized and safety is a concern, so a contractor
> with
> experience in such repairs is vital.
>
> if you describe the preliminary visual observations in a bit more
> detail, i
> may be able to assist further.
>
> HTH
>
> Regards
>
> Mark
>
> ------------------------------------
> Mark Geoghegan BE (Hons.-Structural)
>    S T R U C T U R A L   T E C H
> AUSTRALIA    -   GUAM    -    HAWAII
> ------------------------------------
>
> >Subject: Concrete Deck Tendon Repair
> >
> >Story:
> >On an existing parking garage concrete slab, post-tensioned tendons
> are
> >exposed at the deck surface because the concrete coverage was a
> little
> >thin.
> >At a few locations the tendons' sheathing is damaged.
> >
> >Question:
> >Are there any suggestions or sources of information for repairing
> the
> >sheathing?
> >
> >
> >Sharon Robertson Bonds, PE
> >Salerno/Livingston Architects
> >363 Fifth Avenue, Third Floor
> >San Diego, California  92101
> >(619) 234-7471
>
>
>
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