Systematically Testing Post-Installed Anchors?

[Archie264]

Is there any practical and cost-effective way of load-testing post-installed anchor bolts as they are installed? From a quick internet search I saw the following gadget, along with other similar apparatuses (apparati?):

http://www.ndtjames.com/Anchor-Test-System-s/38.htm

Has anyone here had experience with this type of thing? I know the post-installed anchor manufacturers are emphatic that to achieve capacity capacity the installation procedures must be followed exactly. But short of someone watching over the installers' shoulders full-time what's to ensure that will happen? Further, even if it is, what's to guarantee the exact condition of the concrete at all locations? It seems to me that this is an issue that would have been addressed long ago but thus far I haven't found too much regarding it. What am I missing, I wonder?

 

[Ingenuity]

Post-installed ADHESIVE anchors?

 

[TLHS]

Proof testing anchor rods, especially post installed ones, is pretty typical in some parts of the world. Search for anchor proof testing or pull testing and you'll find a lot.

 

[Ron]

We have a similar device for testing smaller fasteners. For larger fasteners we use a ring spacer made from an 8" dia pipe with a flat plate on top, a coupling and all-thread rod extension going thru a calibrated center pull jack. This setup is accurate and a lot less expensive than a dedicated fastener tester (we can use the jack for a variety of load tests)

 

[Ingenuity]

For post-installed ADHESIVE anchors in the US, "...because ACI 318-11 has been adopted by the 2012 International Building Code (IBC), whenever the 2012 IBC becomes effective in a state or other jurisdiction, ACI 318-11 effectively will be law..." so that requires adhesive anchors under sustained tensile load to be undertaken by certified Adhesive Anchor Installers. ACI conducts such cert classes, and also Inspector classes too. Link

I took the Installer class - both written/theory and practical exam - the practical exam is rather difficult - the overhead anchor simulation samples are cut in half and examined for % of voids, and pass/fail based upon the voids. Typically, the pass/fail rate of classes is about 50%. Even installers with 30 years experience are failing - been doing it wrong for all those years, maybe!

Interestingly, every aspect of the adhesive anchor installation (for anchors under sustained tensile loading) has to be undertaken by a certified installer - drilling, hole cleaning, epoxy install, and anchor installed - so a crew of 3 or 4 installing such anchors, all members, not just one member, who carry out any aspect of the anchor work have to be certified.

I don't think there is any systematic testing of installed anchors in the field. More often than not it is undertaken when there are "issues" - like no special inspector, install looks crappy, maybe partial failures, did not follow manufacturers printed instructions, etc., OR a federal or state agency requires testing to begin with.

We recently did #10 rebar proof testing for a FAA project. For a CONFINED proof loading test, our set up was as follows: Center-hole bearing/stressing stool, center-hole ram, load cell, and wedge-grip barrel, complete with hydraulic pump and displacement gauges:

For smaller anchors we have 3 ton, 12 ton, 25 ton and 50 ton hydraulic rams, and for very small mechanical anchors, we have an older manual HILTI test unit, originally from Europe. HILTI sell this test unit in all markets except the US:

Simpson Strong-Tie no longer conduct field testing of their adhesive anchors - they leave the testing liability to others!

 

[wannabeSE]

Ingenuity,
Was the 50% failure rate in the class with a piston plug or without? My office has discussed changing our general notes to require the contractor to use a piston plug for horizontal and overhead installation of adhesive anchors.

 

[Ingenuity]

wannabeSE:

Exam failure was possible by failing the written exam, the piston plug practical, OR the end-cap practical.

Only 50% passed all 3 categories and obtained certification for piston-plug AND end-caps installations. Of the 50% who failed, half of them (25% of total) failed the piston plug. Some also failed the written portion.

The cert class now has the option for applicants to only take the piston-plug + written. IMO, no one should be using the end-caps - they don't work. Even Simpson ST personnel have failed the practical exam of end-caps multiple times.

 

[Archie264]

All,

Belated thank you very much. And I know realize there's a lot more to it than I thought. I didn't realize it had been codified in ACI318-11, for example. Also interesting that Hilti sells that device everywhere except the US and that Simpson's folks are failing the certification test. Almost makes me want to through-bolt and plate everything but I know that won't wash. Anyway, thanks again.

 

[MrHershey]

Simpson Strong-Tie no longer conduct field testing of their adhesive anchors - they leave the testing liability to others!

Thanks for mentioning this. Guess I should stop telling contractors that Simpson will pull test their own anchors for free. Curious why they stopped. Wouldn't think there'd be a ton of liability in just pull-testing anchors and reporting results. Unless they were extrapolating where they shouldn't have been or the anchors weren't holding and they'd like to be able to blame it on the tester rather than the installer.

 

[epoxybot]

All those dispensing guns should come with a shoulder strap and probably only the pneumatic guns allowed. Trying to squeeze the manual gun & have a feel for what your doing with the other hand is probably contributing to a high failure rate. They are all too bulking & too heavy. A tube on the end of the static mixer is the way to go.

I was looking for some information on material temperature limits and really didn't find what I was looking for. Even a 10F degree drop in material temperature from lab/data sheet temp of 68F to 73F can have wildly different effects on the A & B components of a particular epoxy formulation. Usually the Resin viscosity shoots way up while the Curing Agent lags behind, leading to a Curing Agent rich mix at the end of the nozzle. It becomes more of a problem with filled materials.

 

[Ingenuity]

Thanks for mentioning this. Guess I should stop telling contractors that Simpson will pull test their own anchors for free.

No problem, however, I probably should clarify: In Hawaii, Simpson-ST do NOT do anchor field testing of their anchors. The local S-ST rep told me it was a nationwide policy, but I can not confirm this. Best to check with your local/regional rep.

Similarly, Hilti in Hawaii do not undertake anchor field testing of their anchors.

 

[hokie66]

If these companies don't provide a testing service, I wouldn't use the adhesive anchors for tension service. But then, I never did anyway.

 

[hawkaz]

If the anchors are inspected, why do you need to pull test them? Don't all of these require special structural inspection?

Ingenuity- From your pictures above, watch out with the first method shown. The jack will push down as much as it pulls up, impacting your break out cone. That is why the Hilti product shown in the 2nd picture has the legs pulled out.

 

[Ingenuity]

Ingenuity- From your pictures above, watch out with the first method shown. The jack will push down as much as it pulls up, impacting your break out cone. That is why the Hilti product shown in the 2nd picture has the legs pulled out.

That is why the first graphic it is called a CONFINED pull-test - it is NOT testing the pull-out cone, only the bond-related aspects of the adhesive/anchor.

To undertake an UNconfined pull-test, where the pull-out cone is applicable, you need a 'bridge' to span across the anchor, as per ASTM E488-15 STANDARD TEST METHODS FOR STRENGTH OF ANCHORS IN CONCRETE ELEMENTS or ASTM E3121-17 STANDARD TEST METHODS FOR FIELD TESTING OF ANCHORS IN CONCRETE OR MASONRY

 

[Yves De Lathouwer]

Hydrajaws is the producer of most of the pull-out tester in the world, including the one used by Hilti.
Here you find their website with all the options

http://www.hydrajaws.co.uk/

For a less precise test, in case you fear that the installation procedure was not followed as required, a very "unprecise" procedure but cheap and quick is to apply a Torque Moment with a short evaluation of the conversion. It's highly not precise but if you fear a really bad installation, it can be pretty usefull.

regards
Yves De Lathouwer
Head of Engineering Department Adit Ltd

http://www.adit.org.il