×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

epoxy for doweling rebars in existing concrete

epoxy for doweling rebars in existing concrete

epoxy for doweling rebars in existing concrete

(OP)
what is your take on the use of epoxy to anchor rebars in concrete.
how does the code fit in the picture here?

RE: epoxy for doweling rebars in existing concrete

Based on my experience, I do not have major problems with Epoxy for dowells in concrete.  In practice, we usually use HILTI ANCHORS or HILTI epoxy with rebars.  However, the dowel-in length must be followed according to HILTI manual.  I had a job failed in pull out force of rebars because the contractors did not dowel deep enough in concrete to develop sufficient bonding force for rebars.  Be carefull, when you design HILTI epoxy system and also specifically require the min. dowel in length for contractors.

RE: epoxy for doweling rebars in existing concrete

A few years back, we used 5000 Hilti C-100 concrete/brick anchors in the earthquake retrofit on one of the buildings at USC.  The Los Angeles county inspectors did a 10 percent pullout and ALL passed.  With this many to install, we used an pneumatic roto-hammer which aided in cleaning out the holes and the  pneumatic Hilti injector tool (expensive) which eased the work load.  In my experience, failure is caused by not following the instructions to brush out and blow out the holes before injecting the epoxy.  With the brick anchors it is difficult not to drill deep enough because the cages stick out too far, but with rebar it is possible and you must have concientious and qualified workmen doing the installation.  Newer epoxies are now being used and you seldom see the C-100 any longer.  As an engineer it would seem a certain redundancy in this type of installation would be of benifit.


Rod

RE: epoxy for doweling rebars in existing concrete

Epoxy anchors are not specifically covered in building codes yet.  ACI is in the process of developing code requirements for various types of post-installed anchors for the next code cycle.  In the meantime, such anchors are covered by ICBO or NES evaluation reports.

The quality of epoxy anchors is generally very good.  One thing to keep in mind is that the epoxies typically lose significant strength at high temperatures.  So be careful if you are using them in fire-resistive construction.

RE: epoxy for doweling rebars in existing concrete

Also, curing times in cold weather is a problem.  Do not use epoxy in weather colder than 40 degrees F.  Another thing is clean out of holes.  If the holes are dirty, the bond strength is reduced.

Now, Hilti has a new product the HIT RE 500 epoxy they say can cure at temps down to 23 deg F.  They also have a new bolt that can be placed in dirty holes.  I think its called the HIT-TZ bolts.

RE: epoxy for doweling rebars in existing concrete

So a remark is that maybe when non redundant to an independent structural system these adhesive connections should be forbidden when they may be affected by (fire) heat...to what extent, or under which protection, or to what temperature?

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources