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  • 1.  Epoxy Set Anchor Bolts

    Posted 10-29-2019 07:50 AM
    Edited by Tirza Austin 10-29-2019 07:49 AM
    Hi all, I am a construction manager/engineer on a residential project in the western pacific. The contractor has poured a 10"x8" concrete bond beam around the top of the exterior wall per the plans (about 150 LF total). The bond beam has #3 stirrups spaced at 4" OC. The contractor failed to set the L anchor bolts during the pour. The plans for a separate house call for the anchor bolts to be set in an existing concrete bond beam with Sikadur 32 Hi-Mod.  This epoxy is a high strength bonding agent and is moisture tolerant. My question is how long should I make the contractor wait before drilling and setting the anchor bolts? 

    I am aware of the 21-day rule specified for adhesives in the ACI 318. It is not clear that this applies to epoxy (as they are different).  I have read other documents that state to wait 7 days. I feel that this should be considered a small pour and the concrete cured at a pretty rapid pace with the heat on this island. I have not had any trouble on previous projects setting anchor bolts with high strength epoxy 24 to 36 hours after the pour. The owner has a new engineer on staff that is trying to challenge my position. Any assistance or guidance is much appreciated. 

    Thanks,



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    Hamilton Smith P.E., M.ASCE
    Austin TX
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  • 2.  RE: Epoxy Set Anchor Bolts

    Posted 10-29-2019 08:36 AM
    It is a matter of judgement.  The only way to know for sure is to follow the manufacturer's instructions.  Call tech support if needed, they can be pretty quick with an answer.

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    Chad Morrison P.E., M.ASCE
    Professional Engineer
    Greenville RI
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  • 3.  RE: Epoxy Set Anchor Bolts

    Posted 10-30-2019 07:46 AM
    I concur 100% with Chad's comment.

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    Kenneth Clark P.E., M.ASCE
    Civil Engineer
    Oklahoma City OK
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    Original Message


  • 4.  RE: Epoxy Set Anchor Bolts

    Posted 10-30-2019 10:35 AM
    Go with a mechanical concrete anchor such as a Simpson (Titan), Ram​set, etc. Not many residential carpenters qualified per minimal ACI training requirements for adhesive anchors.  Also, concrete screws have better values.  They have a reduction on new concrete installations if under full loading.   Make sure whatever you do that it is ok by your Structural Engineer of Record.  SE might require full special inspection.  With wall panels, nobody cast in anchors anymore.

    MGF
    Prof Eng


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    Mark Flott P.E., M.ASCE
    SUBSTATN ENGR
    Papillion NE
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    Original Message


  • 5.  RE: Epoxy Set Anchor Bolts

    Posted 10-30-2019 11:09 AM
    It is a good idea to call the manufacturer as Chad Morison stated above. In my judgment, 7 days is good enough to allow contractor to keep working. Since you have a new Engineer assigned, let him make the decision and don't feel that you are challenged, this is just part of our work. Ultimately, he is the responsible in charge.

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    Mohamad Annan P.E., M.ASCE
    Transportation Engineer
    Clovis CA
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    Original Message


  • 6.  RE: Epoxy Set Anchor Bolts

    Posted 10-30-2019 07:46 AM
    If you do decide to set the anchors prior to 21 days, I would recommend a load test of the installed anchors to show that they can develop the required strength.

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    Jason Draper P.E., M.ASCE
    Burns & McDonnell
    Kansas City MO
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  • 7.  RE: Epoxy Set Anchor Bolts

    Posted 10-30-2019 09:18 AM
    I agree with this suggestion.

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    Michael Hershey P.E., M.ASCE
    Executive Director
    New York NY
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    Original Message


  • 8.  RE: Epoxy Set Anchor Bolts

    Posted 10-30-2019 11:45 AM
    I also agree with that and also checking with the manufacturer.
    In that way the owner's engineer would have nothing more to say.

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    Napoleon De La Colina Ing., A.M.ASCE
    Eng Mgr
    ICM - Ingenieria Civil Montajes
    LIMA
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    Original Message


  • 9.  RE: Epoxy Set Anchor Bolts

    Posted 10-30-2019 11:45 AM
    I've done heavy civil construction and have run across this situation upon occasion.  I don't know if you took concrete cylinders, but a 7 day break should be at 80% capacity if you are to determine you are on track to achieve concrete strength.  It is possible to determine the yield capacity of your L lags as the diameter of the bold and steel grade.  This is the capacity you want in your epoxy substitute.  We calculated a conic pull-out capacity of our concrete to determine required bolt depth at 125% capacity (ignore stirrups).  Lag embedment is variable with changing conic surface area so setting up the equation for capacity will yield depth.  We then chose a low creep epoxy to sustain that load.  As an added tip, the contractor *Must* blow out the holes thoroughly before applying epoxy.  That little bit of drill dust can dramatically reduce pull out capacity.  In the end, if a pull-out test is conducted (on a set-aside test bolt), you should find you have reliable full capacity for your design.
    Matt

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    Matthew Socha P.E., M.ASCE
    Transportation Engineer
    Eureka CA
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