[lowROLLERchevy]

The shop i work at has a single lift, and one side of the lift was bolted to a patch of concrete that caped an old oil change pit. Turned out that that concrete was NOT suitable for bolting a lift to.

Last week the concrete there gave out, and to repair it we broke out a 3 x 4 section of the old concrete, compacted everything below, and poured a foot thick pad.

Yea ... 12+ inches of 5000psi concrete.

So now we've been told that we need to wait a full 4 weeks before we bolt the lift back down and use it again.

Is this correct or can we knock a week or so off that ?

 

[Cape Cod Bob]

http://www.ehow.com/info_8620507_long-concrete-driveway-dry.html :welcome:

 

[DanielC]

You might be able to knock a week off, and then wait another four weeks to do it again.

It seems there is never enough time to do something right, but then it takes up even more time being done over.

 

[327NUT]

An old saying by my Dad......"the hurry'r I go the behinder I get". And man is that ever true. By the way, since it's 12" thick, did you guys or the contractor (?) build a rebar cage of sorts to help strengthen the concrete?

 

[geezer69]

12"thick takes 100 years to completely cure. it will be at 90% of its strength in 28 days. it will be at 80% pluss in one week. bolt it down. you aint gona hurt nothin.

 

[lowROLLERchevy]

An old saying by my Dad......"the hurry'r I go the behinder I get". And man is that ever true. By the way, since it's 12" thick, did you guys or the contractor (?) build a rebar cage of sorts to help strengthen the concrete?

I wanted a 3'x6' slab, maybe 8" thick at most, pinned to the old pit walls on either side, and rebarred all together.

I was overruled.

 

[geezer69]

if it aint pinned with drilled in rebar where it contacts the old concrete it aint rite and i wouldnt trust it . its just a foot sittin in a dang hole now. 3x4 is a purdy good size but id keep an eye on it.

 

[dinger]

Is this footing surrounded by concrete or exposed on one or more sides? I would be more concerned of the footing breaking away if it is not completely surrounded by the old concrete. Did you set the bolts or are you going to drill? Regardless, I wouldn't do anything for at least 3 weeks.

 

[boatbob2]

Huh???????????

Hi,this little slab you poured,is the re-bar tied into the old re-bar?have holes been drilled into the old concrete at least 6 inches deep? (preferably 12 inches deep)? and re-bar jammed into the hole? then all tied together? if not,the weight of a vehicle on that peg leg hoist,will cause the new cement to drop down further.WAIT FOR AT LEAST 3 WEEKS FOR A PARTIAL CURE.wouldnt it be nice,to be working under the vehicle,only to have the pad collapse ON YOU???? your boss is an IDIOT,ill bet HE doesnt get under that hoist...DO IT RIGHT,OR DO IT OVER...... :nono: :smash: ain: :spank:

 

[MARTINSR]

We are talking about a two post lift right? The forces at that point where the lift bolts to the floor is a heck of a lot more than just down, the are also UP. That lift mounting is subjected to rocking, lifting up on the front and rear of the mounting. It had BETTER be done right, and it is nothing to screw with!

Brian

 

[Steel]

When I poured mine, I built a 30" square box 16 " deep caged with wire and rebar. I also watered my floor religiously for a month before I drilled and mounted my posts, no problems yet...

I would say as long as it is set up right, 30 days is plenty to bolt it up and be safe....

The only thing you dont see in the pics is the actual re bar and fencing that was installed prior to the pour.....

 

[lowROLLERchevy]

yes this a 2 post lift.

The north and south sides of the new pad butt up against the most horrible concrete work i have ever seen. the pit was filled almost to the top with random rocks and broken concrete and then a layer of concrete was used as icing..... as little as 1" of concrete in some spots.

The east and west sides of the new concrete butt up against the old pit walls. ni pinning or rebar were used in the pouring of the new pad.

Amazingly the old concrete cap didn't drop at all when the lift ripped out despite the fact that the rubble fill had settled an inch over time.

We didnt set anchors when the concrete was poured, we will be drilling new holes. All we did was jack the lift up on that side and put in on blocks & 4x4's... there was no way to figure out the proper location of embedments

 

[boatbob2]

Rip it out !!!!!!!!!!!!

Sounds to me,like you dont have a base for a 2 hole lift,time to rip the COMPLETE prior concrete work OUT,and start over.IF someone gets hurt IF AND WHEN,that concrete fractures,dropping that lift with a car on it,the bosses insurance company will refuse to pay for the damages,RIGHTLY SO.the guy that gets hurt,OR family if hes killed,will sue the crap out of the boss,AND/OR the boss is going to JAIL,HAVE a FRIEND phone OSHA,if you dont want to be identified.i would call in a heartbeat,send ME an EMAIL,and i will make the call,BUT,i will need ALL the info.im just an old guy,that gets pi---d off,when safety is no concern to employers. :nono: :nono: :nono: :nono: :nono: :nono: :nono: :nono:

 

[Jimbo17]

Cure time for New concrete

I have been in the building business for 40+ years and the cure time for New concrete has always been 28 day's.

Once you pure concrete you will notice it has a dark green kind of color to it but as it cures the color get's a much light shade of grey.

When we used to pure a slab of concrete you can walk on it the very next day but if you were to take a hammer and hit it on a corner the corner would break off.

Within a few days of pouring the slab we would install sill bolts which are the 2 X4'S for the bottom plates of a wall but we never tightened them now completely because you would pull them right out of the concrete.

Wait the 28 day's and do it the right way.

Jimbo

 

[sbchevfreak]

From your description of the existng floor, and the new concrete work, you could not pay me enough to lift a vehicle on that hoist, let alone walk underneath it!!! This piece of equipment holds YOUR LIFE in the balance. Tell your boss to do it right, or walk away. This guy cares ONLY about the bottom line, your safety means absolutely NOTHING to him. Whn a lift collapses, not fails, but collapses, you CANNOT move fast enogh to save your life. When that lift falls, and it will, whoever is under it will be killed, or at best grieviously injured. Do not let that person be you, and report the shop as unsafe to health and safety.