Concrete and a lift???

[dreamingmuscle]

Ok no bashing or get a lawyer talk. I've resolved the problem with the contractor to my satisfaction.

Any way the hired hands that built my pole barn decided it was a good idea to add 80 gallons of water to each 9 yard cement truck. I complained loud and clear to the owner and reached a settlement with him.

I had the slab core drilled and it tested to a average of 2350 psi. I did have the area where I planned for the lift to be dug out to 8 inches thick.

So even though the psi strength is less than desirable. Does anyone think I should be ok by using longer anchors and epoxy in the holes to anchor a two post lift?

Cutting out the slab will a bear because of the thickness. I'm willing to go that route but would rather not. If you know what I mean.

I have access to some half inch steel plate, and could make the base plate bigger with more anchors. Would that help at all?

Thanks Glen

 

[kelpaso1]

80 gallons of water added to a truck load? WTF? Inept concrete idiots if you ask me Why is there so many bad concrete jobs lately? Are these guys so f'ed up on dope or what?

 

[Ironcrow]

Yes, of course it can be done. It depends on the lift and what you are going to put on it. The thickness of the pad helps. A larger mounting base helps. You need to have someone comfortable with the calculations help you.

 

[James-W]

I am assuming you are talking about a 2 post lift instead of a 4 post lift. Are they going to anchor the new concrete into the old by drilling into the old concrete, installing rebar, then poring the new thicker concrete?

 

[dreamingmuscle]

I am assuming you are talking about a 2 post lift instead of a 4 post lift. Are they going to anchor the new concrete into the old by drilling into the old concrete, installing rebar, then poring the new thicker concrete?

Two post. There is no old at this point. I haven't made a final decision on whether to go with what I have or cut and replace. But yes if I do cut and replace all will be tied together.

 

[dreamingmuscle]

80 gallons of water added to a truck load? WTF? Inept concrete idiots if you ask me Why is there so many bad concrete jobs lately? Are these guys so f'ed up on dope or what?

Slurry self levels.

 

[dreamingmuscle]

Yes, of course it can be done. It depends on the lift and what you are going to put on it. The thickness of the pad helps. A larger mounting base helps. You need to have someone comfortable with the calculations help you.

Where does one find such a person without spending as much money as cutting and replacing the concrete.

 

[ItsNemo]

They screwed up...get them to come back and cut out and re-pour properly for the lift following the mohawk directions.

 

[dreamingmuscle]

They screwed up...get them to come back and cut out and re-pour properly for the lift following the mohawk directions.

As stated above I've reached a fair settlement with the builder. It's all on me now.

Glen

 

[James-W]

Two post. There is no old at this point. I haven't made a final decision on whether to go with what I have or cut and replace. But yes if I do cut and replace all will be tied together.

I probably should have been more clear, but when I said old concrete I was referring to the concrete they already poured that was done wrong.

 

[8mpg]

I'd cut it and repour the lift area. What will be cheaper... cut and pour or a car that fell off a lift because the concrete broke and possibly injured you?

What size lift? I don't think you really need an 8" thick pad for the lift.

 

[dreamingmuscle]

Yeah I tend to over kill things. Especially when I'm not sure of what I'm doing.

Glen

 

[Low50s]

Ok no bashing or get a lawyer talk. I've resolved the problem with the contractor to my satisfaction.

Any way the hired hands that built my pole barn decided it was a good idea to add 80 gallons of water to each 9 yard cement truck. I complained loud and clear to the owner and reached a settlement with him.

I had the slab core drilled and it tested to a average of 2350 psi. I did have the area where I planned for the lift to be dug out to 8 inches thick.

So even though the psi strength is less than desirable. Does anyone think I should be ok by using longer anchors and epoxy in the holes to anchor a two post lift?

Cutting out the slab will a bear because of the thickness. I'm willing to go that route but would rather not. If you know what I mean.

I have access to some half inch steel plate, and could make the base plate bigger with more anchors. Would that help at all?

Thanks Glen

Ok my thoughts on your questions are .
1 - has the concrete been full cure to get that 2350 psi?
2- if you were to decide to mount a 2 post on that slab you need to make sure you were to frequently check the bolt tightness and vehicles properly spaced.
3- greg smith according to the oh-10x wants 4" at 3000psi and same with some of the other manufactures.

Personally if it was me. id give it a shot and monitor everything. you can remove the lift and repour if you need as long as you dont have a car come crashing down. if you are worried you could have a welding shop extend the feet for a larger stance and then you could add more bolts but that would also create more tripping hazard.

how many people buy a home that was built by someone else and throw up a new lift in a garage not knowing what the contractor that built the home did ?

 

[wssix99]

So even though the psi strength is less than desirable. Does anyone think I should be ok by using longer anchors and epoxy in the holes to anchor a two post lift?

You are definitely not OK with the lift as-delivered. Longer anchors would definitely be needed, but the question is: How much longer do the anchors need to be to enlarge the stress cones so they give you the same factor of safety that the original anchors would in spec concrete?

Maybe your lift manufacturer would tell you? (I'd share that you had a core tested, that's something precise for them to work with.)

I'm not a fan of using epoxy. Most of the world uses the mechanical anchors for a number of reasons. If you don't get a good bond at the bottom of your hole, then the whole thing is orders of magnitude weaker. (With a mechanical anchor, you know 100% where it's biting.)

I did have the area where I planned for the lift to be dug out to 8 inches thick.

This may actually be working against you. The lift instructions don't call for this (they call for normal flat slabs) because it introduces several mechanisms where the slab can develop cracks around the thickened area. I would be more concerned about this where the concrete is of poor quality.

I've probably talked enough about the details regarding this in other threads, but in your situation (once you get to your 30 or 60 day cure points), I would wet the floor lightly to make sure you don't have any hairline cracks developing along the edges of this thickened area. If so, the area will need to be cut out for that reason, alone.

 

[dreamingmuscle]

Ok my thoughts on your questions are .
1 - has the concrete been full cure to get that 2350 psi?

It cured 6 months be for being tested.

You are definitely not OK with the lift as-delivered. Longer anchors would definitely be needed, but the question is: How much longer do the anchors need to be to enlarge the stress cones so they give you the same factor of safety that the original anchors would in spec concrete?

Maybe your lift manufacturer would tell you? (I'd share that you had a core tested, that's something precise for them to work with.)

I called both rotary and bendpac. They both took my information and promised to call back but didn't. Maybe I should call a installer??

I'm not a fan of using epoxy. Most of the world uses the mechanical anchors for a number of reasons. If you don't get a good bond at the bottom of your hole, then the whole thing is orders of magnitude weaker. (With a mechanical anchor, you know 100% where it's biting.)

I would use both epoxy and Red Heads. Over kill maybe??



This may actually be working against you. The lift instructions don't call for this (they call for normal flat slabs) because it introduces several mechanisms where the slab can develop cracks around the thickened area. I would be more concerned about this where the concrete is of poor quality.

I've probably talked enough about the details regarding this in other threads, but in your situation (once you get to your 30 or 60 day cure points), I would wet the floor lightly to make sure you don't have any hairline cracks developing along the edges of this thickened area. If so, the area will need to be cut out for that reason, alone.

It's been almost two years since the pour was done. There are some hair line cracks thru out the slab. It was fiber glass reinforced no rebar though.

Thanks wssix99 this was the kind a informative reply I was looking for.

Glen

 

[firebirdparts]

I will just add that the lift itself can be modified to improve the situation, but the manufacturer probably won't like that. Instead of more anchors the bigger benefit would be spreading them out and getting them farther away from the supposed fulcrum. My opinion.

 

[matt_i]

Just cut it out. Its just work. You don't even have to form it...

I would edge-dowel the existing slab to keep everything aligned though.

 

[mcbassin]

Dang that's a hell of a deal....I hate to hire this kind of work out. Seems like it always ends up with me being disappointed with the results.

 

[Stellaontap]

Just cut it out. Its just work. You don't even have to form it...

I would edge-dowel the existing slab to keep everything aligned though.

I agree....not that much work for peace of mind. I assume you ordered 3000 psi concrete and after 6 months you are at 78% of your design strength of where it should have been at 28 days. Don’t forget that with the decrease in compressive strength you have also decreased the shear and flexural strength of the concrete.

Eric

 

[LX-Markham]

Initially I thought "cut it out and re-do".
But I would wait until you hear back from the lift manufacturer. They may suggest a different anchor.

 

[nolimits76]

I've been in heavy commercial & civil (road/bridge) construction for 20+ years. In that interim I've seen a lot of goof ups and fixes done. Some quality stuff figured out by guys in the field doing the work, and some that required engineering solutions.

If I'm hearing you correctly, you want a peace of mind that comes from an engineered solution. I get that and would probably like the same if I were in your situation.

I'd recommend you get in contact with independent engineer that specializes in this sort of work. I have a guy I used (and still use) on occasion. I'm not sure what you consider a small or large cost, but I'd think about $500 or so would get you an engineered solution and some basic details/plans to build to.

The issue I've seen in these situations is that the solution is rarely "yep, it's okay". I think best case scenario would be longer anchor bolts. Whoever looks at the design can make a recommendation on the best type. Anytime you drill/epoxy bolts, it is critical to blast the holes with air and get them clean so the epoxy adheres properly to the concrete and not the dust. While I admit that epoxy isn't my first choice, there are some great products and when done properly they do offer a good solution.

Being from OK, the guy I use is also from OK but I can share his contact info if you can't find anyone local to you. You can send over slab details, test reports, etc. along with the specs on the desired lift and how you'd like to proceed. He will then do the calcs and provide a solution that works.

 

[ConCretin]

I was also curious how old the concrete was when you had the cores cut. Concrete anchors are typically rated by the psi of the concrete and depth of embedment. You can probably find a deeper anchor that gives you the same or better ratings as the original anchors in 4" of 3000 psi concrete. I guess the good news is that you know how strong your concrete is and can select your anchors accordingly. I suspect a lot of guys have put lifts on slabs without that info.

 

[ItsNemo]

As stated above I've reached a fair settlement with the builder. It's all on me now.

Glen

How fair? I would hope they have given you enough back to cut out and re-do the section they screwed up. If not, I wouldn't call it fair.

 

[dreamingmuscle]

How fair? I would hope they have given you enough back to cut out and re-do the section they screwed up. If not, I wouldn't call it fair.

Not that it matters, but the cost of the cement it self. Which was $2600. Could I sue for more sure? Would I win, probably? Would I be able to collect, probably not. So in the end only the lawyers would have won.

I did forget to add that I lnstalled two chain anchor pots in the slab they look similar these below.

I hooked up the engine hoist to one and pulled till the chain hummed like a violin string and I was sure the 3/8th chain was starting to stretch. The pot didn't give way.

 

[ItsNemo]

Not that it matters, but the cost of the cement it self. Which was $2600. Could I sue for more sure? Would I win, probably? Would I be able to collect, probably not. So in the end only the lawyers would have won.

I did forget to add that I lnstalled two chain anchor pots in the slab they look similar these below.

I hooked up the engine hoist to one and pulled till the chain hummed like a violin string and I was sure the 3/8th chain was starting to stretch. The pot didn't give way.

Well that ain't half bad then...$2600 should easily cover the cut/remove/re-pour of a sufficient section to properly install the lift. Nice that they did refund that much for you, definitely not worth fighting for anything more.

 

[69gp]

I am not engineer but i would maybe try this avenue. Find out the size of the footprint of the posts of lift you want. Say its 18" across the widest point. I would then get a coring company to core 24" holes where the feet are going to be located. I would then dig down a few feet and undermine the existing slab as much as I could. Dowel rod into the existing slab. Make sure the steel will not be in the way of any anchors. You could possibly make a template and install your anchors directly into the pour. Cored holes will not lead to cracks forming and will also make for a clean detail when you are finished.No over cutting from using a concrete saw.

 

[Spot84]

I have to cut out existing concrete and pour for my 2 post lift. If you decide to do this each manufacturer will have a different recommendation if you decide to cut out existing concrete and repour. Rotary lift recommends 4'x4'x6" 3000psi for each column(this information is on there website under Frequently asked questions. Doesn't say anything about pinning into existing slab. http://www.rotarylift.com/Support/FAQ/

Greg Smith equipment recommends 4'x4'x10" 3000 psi for each column. They also say to pin into existing concrete with rebar. http://www.gregsmithequipment.com/2-Post-Lift-FAQ-Concrete

I spoke with Bendpak and they recommended a new slab at 157"x113"x4" 3000 psi. This would be one continuous slab between the 2 post. It seems that these dimension would be a stand alone.

After speaking with a very large heavy equipment company that specializes in installing lifts, alignment machines etc the owner also recommended a 4'x4'x6" 3000psi for each column pinned into original slab.

Bendpak and Mohawk both recommend larger slabs. Mohawk actually states there slab would be a stand alone system. http://www.mohawklifts.com/library/manuals/Slab_Require_Recommend_11_07.pdf

Conclusion: I myself have decided to go with 4'x4'x10" 4000psi concrete under each column. It will be pinned into the existing 6" reinforced slab and also underpinned. It will be reinforced with #4 rebar. The rebar will be spaced so that it won't be hit when drilling for anchors.

All of the recommendations are for a 10k 2 post asymmetrical lift.

I pray that this helps friend. The great part is there are some really knowledgeable fellas on here that will offer really good advice. I hope they chime in!

 

[dreamingmuscle]

Wow your 1st post was for my problem! I'm honored to say the least.

I've made up my mind to cut the slab and order in some 4k concrete. A five yard minimum is going to dictate how big I make the replacement pads.

 

[wssix99]

Thanks wssix99 this was the kind a informative reply I was looking for.

I called both rotary and bendpac. They both took my information and promised to call back but didn't. Maybe I should call a installer??

Rotary and Bendpak will have engineers. Whoever designed your lift will care enough to press their engineers on your problem. I wouldn't think your installer will have the necessary skills. (I wouldn't trust the internet for the calcs, either.)

I would use both epoxy and Red Heads. Over kill maybe??

They don't go together. Epoxy for special epoxy anchors. Wedge anchors go in dry.

It's been almost two years since the pour was done. There are some hair line cracks thru out the slab. It was fiber glass reinforced no rebar though.

If you have cracks within the zone your lift manufacturer warns about for installation - you definitely need to cut out the slab. By now, hopefully all of that has stopped.

 

[like2wheel]

Just curious, how large of an area was poured 8"?

 

[dreamingmuscle]

4'x 12' give or take.

 

[lakeroadster]

The lift folks will tell you to find a local structural engineer.

They have nothing to gain and much to loose by diagnosing concrete issues over the phone.

 

[mcbane]

If it were my slab I would cut out and replace the portion that will support the lift.

Unless you got lots of cores I wouldn't trust the 2350 psi figure. Grossly overwatered concrete may not be very uniform in strength since the mix may well have segregated more in some areas - so there is a possibility that a single core might just be the strongest part of an otherwise 1500 psi slab.

The lift manufacturer probably has lots of experience with lifts on concrete specified as 3000 psi. That means they have lots of experience with lifts on concrete specified as 3000 psi and with an as-built strength way over 3000 psi in most cases for most of the service life of the lift. If it has been 90 days or more and you are still at 2350 psi, your concrete is way weaker than concrete that has generally performed satisfactorily with their lifts.

 

[dreamingmuscle]

3. Cores were drilled. 2350 was the average.

 

[wssix99]

3. Cores were drilled. 2350 was the average.

What was the spread between the three?

 

[dreamingmuscle]

10 foot for a total of 20 feet

 

[dreamingmuscle]

Grandson came running into the house when he seen them and exclaimed that a rabbit had dug holes in my floor.

 

[wdrumheller]

I was also curious how old the concrete was when you had the cores cut. Concrete anchors are typically rated by the psi of the concrete and depth of embedment. You can probably find a deeper anchor that gives you the same or better ratings as the original anchors in 4" of 3000 psi concrete. I guess the good news is that you know how strong your concrete is and can select your anchors accordingly. I suspect a lot of guys have put lifts on slabs without that info.

I remember reading information in your thread about concrete thickness, and when I poured the slab in the lift area of my barn / garage, I had them pour the slab under the lift 8-10" thick and used anchors that were 10" long x 3/4" diameter. It was WAY too strong but I've never regretted the extra cost, not one single second.

 

[wssix99]

10 foot for a total of 20 feet

Sorry, how many psi were the samples off from each other?

 

[Ironcrow]

I've made up my mind to cut the slab and order in some 4k concrete. A five yard minimum is going to dictate how big I make the replacement pads.

If 5 yards is as low as the bid goes, your variable cost is the price of the hole . With 5 yards you can get plenty of structure under the lift AND has some left over for a new sidewalk or something (don't waste it)