Concrete anchors/ 2 post lift help

[Scottb37]

Hey yall, long time lurker here. I recently came in to possesion of 9000# 2 post rotary lift. I am almost done with install but hit a snag, one of the 3/4wedge anchors wouldnt tighten and pulled completely through the hole. I am sure this would be a good place for epoxy but I dont know enough about it to be sure. Does anyone have some advice or guidance?

Do I need to epoxy in the wedge anchor or use a new piece of all thread?

Do I need to enlarge the hole before injecting the epoxy? Or use a smaller bolt?

Do the box stores stock an epoxy that is rated for this application or do I have to order some?

Is there an epoxy available that uses a standard caulk gun or will have buy a specialty mixing gun?

Yes, I am a bit naive in this area and I am not afraid to admit it.

Any and all advice is greatly appreciated.

Thanks, Scott

 

[AngryBeaver]

Going to assume you: A) have thick enough concrete, B) used the correct anchors for a lift,

Did you use a rotary hammer, or some harry homeowner "hammer drill"?

If you used the basic hammer drill, your hole is now larger than it should be, hence why the anchor pulled out. the rest of your holes are now comprised. You need a rotary hammer to properly set support anchors for lift that you'll be under.

its your life, not some shelf hanging on a block wall.

Get the next bigger size anchor... Get a rotary hammer, or pay someone to do it correctly.

epoxy is a great addition to a properly fitted anchor. IT IS NOT a bandaid for an anchor that has pulled through, from too large of a hole or too weak of concrete when your life is underneath a lift.

 

[matt_i]

Epoxy works great if the hole is fully blown out with compressed air with a nozzle that can reach the bottom...and if the epoxy coats the entire wall of the hole plus the OD of the fastener.

The problem with leaving any dust is the epoxy adheres to the dust layer instead of the concrete and I can tell you for certain that a dust layer is low strength. The problem wil drilling a hole that's "too small" is that nobody wants to take the time to take a little coathanger and coat the walls of the hole plus a gloved hand and wipe it on the OD of the fastener and then twist it all the way to the bottom of the hole. And so the epoxy ends up with only a partial bond the rest being air gaps. The epoxy is strongest in shear with a thinner layer but the practical application says drill a hole oversize and use approx 1/16" of epoxy thickness (OD of fastener + 1/8" dia drill bit) for max reliability.

Home Depot used to sell Sika AnchorFix 2 which is an appropriate epoxy and dispenses with a standard size caulk gun. Be wary of the min cure temp which is approx 50F and give it extra time if its on the colder end, 24hrs would be minimum in any case, to cure fully before attempting to tighten the bolt.

I would spec Grade B7 threaded rod for your app, its available at McMasterCarr its approx a Grade 5 bolt in tensile strength.

 

[Scottb37]

When drilling the holes I measured 5 1/2 inches concrete minimum. I used a Bosch SDS drill and Simpson 3/4 x 5 1/2 wedge anchors. The rest of the bolts are torqued to 110# so far, still have 1 more step to get them torqued to 150# per Rotary's instructions. I am not sure what happened on this particular hole, but I can go up to 7/8 anchor bolt.

Thanks, Scott

 

[wssix99]

Does anyone have some advice or guidance?

Do I need to epoxy in the wedge anchor or use a new piece of all thread?

Do I need to enlarge the hole before injecting the epoxy? Or use a smaller bolt?

100% - Call Rotary. Their engineers will give you the proper advice. We may not. There are many reasons why mechanical anchors are safer and easier to install, but your situation comes up all the time and Rotary will have professional advice for your particular model.

Do the box stores stock an epoxy that is rated for this application or do I have to order some?

Generally, no. Epoxy is generally poor in tensile applications because it creeps. Only a small subset of epoxies are rated for this kind of load.

Home Depot used to sell Sika AnchorFix 2 which is an appropriate epoxy and dispenses with a standard size caulk gun.

Case-in-point, Sika warns about using this product:

https://usa.sika.com/dms/getdocumen...12d07bbe66f/pds-cpd-Sikadur-AnchorFix2-us.pdf

"Limitations THE NTSB HAS STATED THAT THIS PRODUCT IS APPROVED FOR SHORT TERM LOADS ONLY AND SHOULD NOT BE USED IN SUSTAINED TENSILE LOAD ADHESIVE ANCHORING APPLICATIONS WHERE ADHESIVE FAILURE COULD RESULT IN A PUBLIC SAFETY RISK.
CONSULT A DESIGN PROFESSIONAL PRIOR TO USE."

^ This is a creeping epoxy.

 

[aarcuda]

When drilling the holes I measured 5 1/2 inches concrete minimum. I used a Bosch SDS drill and Simpson 3/4 x 5 1/2 wedge anchors. The rest of the bolts are torqued to 110# so far, still have 1 more step to get them torqued to 150# per Rotary's instructions. I am not sure what happened on this particular hole, but I can go up to 7/8 anchor bolt.

Thanks, Scott

I wouldnt go to 150 ftlbs if I had to do it again.

I work in aerospace and spoke with a very knowledgable mechanical engineer who explained that you want the wedge to set into the concrete but not over torque it. Basically youre pulling the stud up forcing the wedges out to grab the concrete and then the bolt is locked in. By going to 150 youre trying to pull the bolt out of the concrete and you can.

The lift it designed to put the weight onto the slabdown through the posts so the force to pull out of the concrete shouldnt be there if the lift is loaded correctly. The lift isnt going to try and run away. it wants to stay upright so you are doing more harm than good by going to 150.

I tried both 150 and ~100 ft-lbs on mine. the bolts at 150 show more thread up top than the others and I HATE IT. The bolts set at 100 are tight and I check the torque on the all a lot and they arent moving.

If I ever do it again I wont go to 150. In fact, I am thinking of replacing those with new anchors at 100 but Im worried the hole will be oversized by the previous bolt and by punching it thru for the new one.

 

[aarcuda]

see this post too! https://www.garagejournal.com/forum/showthread.php?t=146021

 

[Diesel Dan]

Hilti calls for 110 lb/ft for their 3/4" fasteners.