Concrete epoxy lift anchor prep?

[xjfish]

I am proceeding to install a 2 post lift in personal shop and I'm trying to be **** about epoxy prep... Have holes drilled already in minimal depth spec'd concrete for included expansion anchors. I have drilled all the way through concrete. I realize this is not typically recommended. I am going for max embedment with 3/4" threaded rod. Hoping epoxy will run under concrete and create a little extra bite there. No void and the packed sandy subsoil is tight to concrete except for what I have blown out with compressed air. A couple of holes will get cardboard packed down to prevent epoxy runoff. I might need a lot? Using Redhead T7+. It cures very fast and meets specs I could find...

I have cleaned 7/8" holes with a 1" nylon tube/pipe brush chucked in a drill, several times. I also made a reverse blow gun tip to blow upward from drilled hole because the bottom is sand and just a base now. Vacuuming like a madman until no dust comes out. I can twist a finger in the hole and concrete dust still coats it.

How clean does this need to be for epoxy? Like finger lickin' clean? Maybe I should wet the hole brush and spend some more time? Stuff will set up underwater... best kept dry? Holes were initially cleaned out with lift posts moved out of way. They are leveled and loosely bolted together now.

B7 threaded rod will be wire wheeled clean and hit with brake cleaner before install. I feel like I'm going to make a huge mess until I figure out roughly how much is needed per hole... Thanks for any 2c

 

[wssix99]

If you are particular and "****" about this install, why would you use a method that isn't in the manufacturer's instructions.

There are many reasons why manufacturers do not provide this as a safe installation method. The science is challenging to grasp, but the professionals who work for your lift manufacturer have this down. (Some manufacturers will provide epoxy options as back-up/repair options, but I have never seen them use threaded rod.)

The way you are going about this may seem 'strong' but you are inviting several avenues for imperfections and failure of the anchors. Even if you were to throw the lift manufacturer's instructions away, you would still be wise to follow the epoxy manufacturer's instructions for this type of install. (Likewise, you would want to make sure your epoxy is blessed by your lift manufacturer for sustained tension and will not creep. Epoxies that are suitable for wall installations are often not appropriate for tension installs like a lift.)

Any bit of dust is an area where the epoxy will not bond to the concrete. Any dust is bad dust.

 

[xjfish]

If you are particular and "****" about this install, why would you use a method that isn't in the manufacturer's instructions.

There are many reasons why manufacturers do not provide this as a safe installation method. The science is challenging to grasp, but the professionals who work for your lift manufacturer have this down. (Some manufacturers will provide epoxy options as back-up/repair options, but I have never seen them use threaded rod.)

The way you are going about this may seem 'strong' but you are inviting several avenues for imperfections and failure of the anchors. Even if you were to throw the lift manufacturer's instructions away, you would still be wise to follow the epoxy manufacturer's instructions for this type of install. (Likewise, you would want to make sure your epoxy is blessed by your lift manufacturer for sustained tension and will not creep. Epoxies that are suitable for wall installations are often not appropriate for tension installs like a lift.)

Any bit of dust is an area where the epoxy will not bond to the concrete. Any dust is bad dust.

Thank you. I know you are not a fan of epoxy anchors, and I understand to a point. I will spend considerably more time prepping and cleaning. I have spoken with 2 "professional concrete guys" who have approved of my "plan" for this project. Lift will be tested/used carefully. I have no reason to believe epoxy will fail? Why would it assuming install not botched? IF the concrete ever shows signs of failure, its will be remedied.

 

[Doubled33]

I am not a fan of epoxy anchors when the concrete is drilled all the way though.

with that said for piece of mind if you brush and vacuum your holes 2 or 3 times you should be fine on bite. However The drilled through concrete may not let the epoxy push to the top and get good engagement. when you epoxy bars or threaded rod you insert slow and listen for a little pop of the released air.

If you are really worried pull test them after the epoxy sets.

when they fail from a dirty hole you generally won’t get a lot of force before it will pull out.

 

[wssix99]

Thank you. I know you are not a fan of epoxy anchors, and I understand to a point. I will spend considerably more time prepping and cleaning. I have spoken with 2 "professional concrete guys" who have approved of my "plan" for this project. Lift will be tested/used carefully. I have no reason to believe epoxy will fail? Why would it assuming install not botched? IF the concrete ever shows signs of failure, its will be remedied.

Epoxy anchors are great, perform similarly to mechanical anchors and have their own stellar benefits.

The challenge in an application like a two post lift is that one needs to go through a lot of extra steps with specialized equipment in order to confirm if they have bonded properly and safely to the concrete. (This makes epoxy impractical to work up to 100% safe solution.)

When a mechanical anchor is embedded in the concrete, it will hold torque and that is our assurance that the failure point will be the concrete floor. (If the floor fails, we can obviously see it.)

Epoxy would require a load test to give the same level of assurance that the bond has been achieved it it will transfer the load to the concrete.


Without a test, one is just guessing and hoping that the epoxy is good. Instead of the concrete failing first, the anchor could just pop right out of the hole.

The other complication is that if one wanted to test epoxy anchors for a lift, one would need to work with the manufacturer to confirm what the test should be run to. Here's an article that calls out some common/standard tests, but they test to the anchor strength and not the full design of the concrete. If one were to pick an anchor stronger than the lift manufacturer designed, the epoxy test could break the concrete, would also be a bad thing: https://seblog.strongtie.com/2020/0...guidelines-on-proof-loading-adhesive-anchors/

 

[claymont]

Simpson Strong-Tie® Anchor Designer™ for Concrete

 

[Rusted Nut]

As long as your holes are the correct diameter for the anchor rod you are using, which by your description they are, you should be good to go. If you drilled all the way though, you can stuff a piece foam in the bottom of the hole to prevent epoxy from bleeding out. Make sure you squirt out some epoxy before placing in the hole, to make sure it is properly mixed, you can tell this by the color, per manufacturer spec. I’ve had hundreds of anchors, both expansion and epoxy tested, I would have no issue getting under your lift. Make sure to follow manufacturers instructions for cure/bolt up/torque/cure time.