68gtxman
I used to reMember
Even with the control joint.
Anchor depth
- Thread starter Evan Dutch
- Start date
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Evan Dutch
Well-Known Member
I’m going to get the highest psi I can find it’ll be 12in deep and most likely fiber reinforced
68gtxman
I used to reMember
The pin should be tight in the hole. When people are tying two large slabs together, one end of the pin is epoxied in and the other end is greased - but they use expansion joint filler between the two slabs. You won’t be doing that.
No, you won’t be compromising the 4” slab. Just center the pin in the thickness.
Sure, fiber mesh reinforcement is fine, but you will see some fibers sticking up on the surface when you trowel it out. It will just look a little funny. Still use the 4 rebar (2 each way) in the new concrete.
Sure, digging out a little under the 4” Sides will help ensure the pins never shear, though I don’t think it’s really necessary. Do it if you makes you feel better.
If I was doing this, I would not include the 4” of already pour floor in my measurements. I would buy or rent a post hole digger and dig further into the pit to make a column. Another 18” give or take, I would hammer the rebar in the hole and leave enough of it to insure continuity…..
Evan Dutch
Well-Known Member
I’ve got a post hole digger. Would 12inches below the 4inches work? Giving me a total depth of 16in of concrete. Hammer vertical rebar into the floor of the hole below the point in which the anchors would be placed. so that there is no chance of hitting rebar with an anchor? Change the entire depth of the pit correct?
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Evan Dutch
Well-Known Member
ok. Would 1/2in rebar be overkill? Should I line just the floor of the new holes with vapor barrier or the floors and the walls? Would I pour the squares to where they cover the control joint and then recut the joint in the new concrete to match the existing control joint? Or pour the concrete to where the existing control joint is not disturbed.
Sorry if I’m asking to many questions. I want to do this right, and once.
The joint has not value here, these are placed to let the concrete follow a predetermined line to allow hair fractures to surface without causing surface factures. Another words cut your hole that is best suited for your application. After your pour I would use a joint trowel and joint the new area.
68gtxman
I used to reMember
No vapor barrier on the walls - just the bottom. 1/2” rebar is fine. The control joint is most likely just a saw cut that is 1” deep (1/4th the depth of the slab). Just cut right through that joint (put your saw blade right in it and saw the rest of the way through the slab) and dig it out. If the joint is really an expansion joint, there will be a filler board in it. In that case, cut the filler out inside your new hole and butt the new concrete directly against the existing concrete. You don’t need to recut the control joint in the new interface. That interface will already be the weak spot that will crack before the uncut slab will crack. Control joints are used to direct where the slab will crack.
Evan Dutch
Well-Known Member
It is a 1in control joint. Cut when the concrete was still wet.
So if it is placed in the orientation shown with the lift columns being placed 6” from where the edge of the new slab is poured. Would this be a problem? Since the interface where the new concrete meets the old is 6” from the lift columns? If a crack forms
68gtxman
I used to reMember
No problem. Cracks do form in concrete. That doesn’t mean it will fail. The pins and rebar will keep it all together.
Evan Dutch
Well-Known Member
or should I pour the new slabs in a way so that the lift columns mount directly in the center of them? This would place the new slabs so that the current control joints intersect them
68gtxman
I used to reMember
That would work too, and would be preferable. It won’t matter if the control joint dead ends into the new concrete sides. But as @Dicer recommended, use an edging tool to round over the perimeter edge of the new concrete, as it will likely crack in that joint. A rounded over edge would hide the crack and likely direct it/them around the new concrete and not across it.
Do not worry about the joints...its nothing but a thing.. and yes I would place the lift in the center of your new pour.....
Evan Dutch
Well-Known Member
Using a tool like this to round the edges correct? This would essentially give me small control joints around the perimeter of the new slabs correct?
Evan Dutch
Well-Known Member
1/2 diameter rebar acceptable for this as well? If using this kind of design, fiber concrete is not necessary right?
does the rebar need to be coated with anything to prevent rusting or am I being paranoid at this point?
68gtxman
I used to reMember
1/2” is great. Yes, that it the correct tool. Fiber is not necessary. Uncoated rebar is fine. The little bit of rust that may form on it gives it bite into the concrete. The rebar lends tensional strength to the concrete as concrete is only really strong in compression.
Evan Dutch
Well-Known Member
Alright.
since the new pad is the primary support of the lift columns. Let’s say I’ve got a heavy load on the lift, would the force being applied to the new pads have any effect on the surrounding 4” concrete that is connected to the new pads with rebar?
68gtxman
I used to reMember
Yes, the pins will transmit part of the load into the adjacent slab. But it will be more of a bending moment force than anything. This will make the smaller new concrete act like it is much bigger than it’s actual size.
Krooser
Building Chinese Free Engines since 1959...
My anchors are 1" diameter and expand after they break thru the concrete. They can never pull out.
As far as concrete strength 4" is plenty thick. Mine is 3 1/2" of six bag mix with fibermesh. I installed my lift in 1995. It's an older model Weaver made from 1" thick steel...weighs over 1500 lbs. itself. I have used it to lift my one ton vans and duallies. No issues ever.
Everyone goes beserk about lifts and thick concrete. I bought a HD 9K lift as it's much stronger than the cheap Chicom junk that had flooded the market. The concrete will never fail.
As far as concrete strength 4" is plenty thick. Mine is 3 1/2" of six bag mix with fibermesh. I installed my lift in 1995. It's an older model Weaver made from 1" thick steel...weighs over 1500 lbs. itself. I have used it to lift my one ton vans and duallies. No issues ever.
Everyone goes beserk about lifts and thick concrete. I bought a HD 9K lift as it's much stronger than the cheap Chicom junk that had flooded the market. The concrete will never fail.
Rule of thumb here is 1 pound of fiber to one yard of cement. Call ahead and ask your cement people, they will add it to the truck before it get to your garage, if you wish. Some rebar is coated some are not, would not worry either way, it's all good, 1/2" dia. is fine.
MiradaMegaCab
Well-Known Member
If you wish you can "hand stone' your edge of the pit before you pour....to make a nice rounded edge.
Evan Dutch
Well-Known Member
Would I still need to round the edge of the new pad as well as the edge of the old concrete?
New pour yes round the edges using the tool you pictured. If you wanted too, but not necessary.... use the tool (hand stone) to have both edges rounded.....just for looks.
Edit: I think it would also keep the edge from chipping....
Edit: I think it would also keep the edge from chipping....
Evan Dutch
Well-Known Member
How deep does the rebar in the pit need to be embedded into the ground?
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