I am in the process of picking up a MaxJax 2-post 6k lift, and should have it this weekend. Odd thing is, I'll actually have the lift before I pour the slab I'm going to use the lift on. Pad will be 4-5" thick, dimensions 24x32. Here's my question. How long will the concrete need to cure before I can set the anchors for the MaxJax?
How long for concrete to cure?
- Thread starter Jason280
- Start date
nehog
Well-known member
30 days unless the manufacturer recommends otherwise.
Streetbu
Well-known member
I thought most lifts required at least a 6" pad, if not more?
readhead
Well-known member
Without knowing some mix specifics it will be hard to know what strength you will have at 7 days. I would wait at least two weeks especialy if you are using the supplied drop-in anchors. 28 days would be best.
We were working on a bridge once and had to wait 60 days before it got up to strength to set the steel. That is not common though.
Since you are going to have a car hanging over your head I would wait at least 28 days. If it will be permanant installation you might consider anchor bolts cast into the concrete. I would still wait to set the lift though.
We were working on a bridge once and had to wait 60 days before it got up to strength to set the steel. That is not common though.
Since you are going to have a car hanging over your head I would wait at least 28 days. If it will be permanant installation you might consider anchor bolts cast into the concrete. I would still wait to set the lift though.
rice rocket
Well-known member
- Joined
- Mar 24, 2011
- Messages
- 3,175
As long as you're not loading it to it's ultimate failure point, does it matter that it's not 100% cured (and if you ask the concrete nerds, it's always curing)? It can cure while you're drilling anchors and working on top of it.
Rookie2
Well-known member
wait as long as you can, 30 days
Milton Shaw
Well-known member
- Joined
- Feb 11, 2011
- Messages
- 4,845
While you are doing it I would put thicker sections under the lift with rebar tying it to the rest of the slab. You have one chance to do it right and never have any additional problems, so do it right and thicken and reinforce and wait until it cured. Yes it will seem like an eternity but in 20 years and crack/trouble free you will thank yourself for waiting and doing it right.
nolimits76
Well-known member
The safe answer is 28 days.
But many times you are at full strength in 3-10 days, depending on the specifics of the mix and temperatures. We've done less, but that was a specialty mix. The only way to be sure is to take enough samples when you are pouring so that you can break them and determine full strength.
If you take samples, make sure you store them in the same conditions as your slab cures. Remember, you want the most representative sample possible.
It's fun to break them....
Edited to Add:
Unless you have the testing equipment available to you, then you can hire out a testing lab to collect the samples and do the tests for you. Obviously, it will be an added cost you pay directly to the lab.
But many times you are at full strength in 3-10 days, depending on the specifics of the mix and temperatures. We've done less, but that was a specialty mix. The only way to be sure is to take enough samples when you are pouring so that you can break them and determine full strength.
If you take samples, make sure you store them in the same conditions as your slab cures. Remember, you want the most representative sample possible.
It's fun to break them....
Edited to Add:
Unless you have the testing equipment available to you, then you can hire out a testing lab to collect the samples and do the tests for you. Obviously, it will be an added cost you pay directly to the lab.
Last edited:
Dan in Pasadena
Well-known member
28 days IS the right answer for the concrete to develop full design strength. That said, most concrete we'll exceeds its design strength and should easily reach 70% of its design strength in 7 days.
Since you'll have the lift before you place the concrete you don't have to drill the slab for anchors after the fact. You can easily and accurately place embedded anchors before placing concrete, have a stronger anchor without hitting rebar for certain and have no worries about damaging the slab.
Since you'll have the lift before you place the concrete you don't have to drill the slab for anchors after the fact. You can easily and accurately place embedded anchors before placing concrete, have a stronger anchor without hitting rebar for certain and have no worries about damaging the slab.
Dan in Pasadena
Well-known member
You CAN make your own. Weld a nut to a plate and embed it but of course it's not galvanized so eventually rust would be an issue....in a few decades! You should never weld on galvanizing if you don't want brain damage.
Dale Leeds
Banned
I agree with the 30 day answers.
RivennHewn
Well-known member
28-30 days is for typical mixes. I've done mixes that hit their design PSI at 3 days.
There are options out there. Talk to a concrete sales person.
There are options out there. Talk to a concrete sales person.
Ross/Kzoo
Well-known member
Here's the rest of your answer, you didn't ask but a necessity. It won't cost much but it'll be worth it.
As far as curing, "You bet your life"!
30 days
Last edited:
Since you are pouring a slab, I'm guessing you have a build in process ? Work onthe interior of the garage while the concrete cures.
You've gone this long without a lift, why rush it now and take the chance of screwing it up, pulling out an anchor or something drastic. Be patient.
You've gone this long without a lift, why rush it now and take the chance of screwing it up, pulling out an anchor or something drastic. Be patient.
Bondo
Well-known member
Ayuh,.... Agreed,... Build in a footer, 'n reinforce it with yer steel attachment points,...
Then wait the entire 28 days for the concrete to cure,...
Ft.ValloniaStreaker
Well-known member
My Grandpa always said, 80 years to cure 80 years to rot......but he said a lot or things like that...lol
willymakeit
Well-known member
If you haven't poured it, Have an engineer take some cylinder of it. They will do a break at 7,14, and 28 days. This will let you know what the strength is. Common practice in commercial work and is required by OSHA before setting steel on bolts.
Sheriff245
Well-known member
- Joined
- Oct 18, 2013
- Messages
- 88
As I was reading the answers and thinking of what to write, I came across this answer. I say +1 on the embedded anchors. Easier, faster and cheaper.
Having cylinders done on site for testing would allow you to determine when is the right time to start using your lift. If not, wait at least 28 days after the pour. As for installation, it depends on the weight of the lift itself, I am not familiar with those, but it could probably be done sooner.
Steve in Louisiana
MEMBER EMERITUS
- Joined
- Aug 9, 2012
- Messages
- 76
Wait 28 days . . .
Buy as high PSI as you can afford. (per yard will only cost a few dollars)
Have structural fiber added to mix. (will reduce spider cracks)
Do NOT let finishers keep adding the water to concrete. Concrete is not supposed to be any where NEAR self leveling. You do not want a soupy pour, it yields weak concrete.
Even if you don't want to spend the bucks on the test, have the cylinders on site & fill three with each truck.
This gets the point across to to your contractor and the finishers that they will be held accountable for a "weak" slab.
They know what those cylinders mean.
My 2 cents . . .
Steve
Buy as high PSI as you can afford. (per yard will only cost a few dollars)
Have structural fiber added to mix. (will reduce spider cracks)
Do NOT let finishers keep adding the water to concrete. Concrete is not supposed to be any where NEAR self leveling. You do not want a soupy pour, it yields weak concrete.
Even if you don't want to spend the bucks on the test, have the cylinders on site & fill three with each truck.
This gets the point across to to your contractor and the finishers that they will be held accountable for a "weak" slab.
They know what those cylinders mean.
My 2 cents . . .
Steve
Todd.Brock
Well-known member
Not sure if plan for epoxy anchors, but I would recommend going much deeper in the area where the lift is going to sit. The epoxy anchors are LONG! If you could go 7 inches in a couple sq ft around each post, that will give you some wiggle room. Just .02 from a guy who has 4" concrete and a maxjack. I will say the epoxy anchors are solid feeling. So many people in the MaxJax thread wish they had thicker concrete, guys are saw cutting and repouring thicker pads, etc.
If you are inclined to dig a little deeper hole , it would go a long way to getting a solid mount when you are ready.
Sent from my iPhone using Tapatalk
If you are inclined to dig a little deeper hole , it would go a long way to getting a solid mount when you are ready.
Sent from my iPhone using Tapatalk
Thanks for the information.
I picked up the MaxJax yesterday, so now I need to get my slab formed and poured. I've considered setting up metal forms/bases and "floating" them on the slab, basically digging two pillars that the slab will pour around. Only problem with this, I'm concerned I may not get them exactly correct, which could cause issues once I bolt in the posts for the lift. Benefit, though, is that they would allow me to use the lift sooner than the Wej-Its.
I've spoken with the local concrete guys, I can get 5k PSI with fibers for basically $100 more than 3k, so the price difference is really moot.
I picked up the MaxJax yesterday, so now I need to get my slab formed and poured. I've considered setting up metal forms/bases and "floating" them on the slab, basically digging two pillars that the slab will pour around. Only problem with this, I'm concerned I may not get them exactly correct, which could cause issues once I bolt in the posts for the lift. Benefit, though, is that they would allow me to use the lift sooner than the Wej-Its.
I've spoken with the local concrete guys, I can get 5k PSI with fibers for basically $100 more than 3k, so the price difference is really moot.
Pathfinder
Well-known member
The 5k PSi and fibers is a no brainer. Well worth the $100 extra. Since you already have the lift I would go with what Dan in Pasadena said and cast the anchor bolts for the lift in the slab.
To do this cut two squares of plywood the exact size of the lift base plates. Trace the bolt holes from the lift onto the plywood, drill and double nut the anchor bolts to the plywood. Fasten the plywood squares to a 2x4 the exact distance apart as required for the lift. Once the slab is pored and bull floated set your anchor bolt jig in place and embed the bolts. Just before steel trowling the slab remove the plywood jig. Wait 7 days and set up your lift. Wait 28 days and use your lift.
John Minton, Architect
To do this cut two squares of plywood the exact size of the lift base plates. Trace the bolt holes from the lift onto the plywood, drill and double nut the anchor bolts to the plywood. Fasten the plywood squares to a 2x4 the exact distance apart as required for the lift. Once the slab is pored and bull floated set your anchor bolt jig in place and embed the bolts. Just before steel trowling the slab remove the plywood jig. Wait 7 days and set up your lift. Wait 28 days and use your lift.
John Minton, Architect