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Discussion Starter · #1 ·
Elec. Contractor here pouring a slab in my job up against an existing slab.

Will do well the two together with rear but my question has to do with the subsurface

it been gravel for years and have various vehicles on it. I feel it's pretty compacted as it is....but does one determine if it's compact enough?
 

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Location?

He will still need to finish grade it, when the machine is there he can scrape it back to see how much is actually gravel. It should have at least 4" of uniform compacted base.
 

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Discussion Starter · #3 ·
Thanks are you saying all the gravel that's there needs to be pulled out and base put back in and compacted?

Location is illinois. I think existing slab is essentially in the same subsurface but not 100% on that
 

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Elec. Contractor here pouring a slab in my job up against an existing slab.

Will do well the two together with rear but my question has to do with the subsurface

it been gravel for years and have various vehicles on it. I feel it's pretty compacted as it is....but does one determine if it's compact enough?

Well, going off of that kind of weird description and not knowing what the slab is for I would say go ahead and pour.

You pays yous money you takes yous chances.

Andy.
 

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Discussion Starter · #5 ·
Lol typed that with phone just saw how jacked it was...sorry try again.

In my 40 X 60 shop I have 20 X 60 slab...the rest is gravel...been there for 10 tears or so. In process of pouring addtl slabs...10 X 40 at a time.

I've removed a lot of the loose gravel..tho most was already near solid from driving and parking. What I thot needed removed I took out and put a few inches of ca6 and tamped.

It feels solid enough to me but was wondering if there's a way to check/measure if it's compacted enough.

It will 5 in of 4000 psi fiber reiforced. For general use and plan for a two post lift.

also will drill and tie to existing slab with rebar...no plans to use expansion mtl against existing slab

Thanks!
 

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Love me some Concrete
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You have to put in expansion somewhere between the slabs and walls! As far as you're compaction, they have a meter that can be used or just pour it and go. DO NOT use rebar over the expansion joint, smooth greased steel dowels or steel dowels with plastic sleeves. If no expansion joint is installed over 60 feet you are asking for problems.
 

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Discussion Starter · #7 ·
Thanks! There's some rigid foam along footings where's sides of new slab will be I thought that to be sufficient there.

For expansion material against existing slab...do I use the black fiber expansion material?

For rebar I was just going to drill existing slab a place the rebar...no epoxy or glue to allow movement.

Can you pls describe the smooth dowel...just greased steel rod? Am I better off just forgetting trying to tie the slabs? Would just placing expansion mtl and pouring be better?

Tganks again!
 

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As for sub-base and this is for your own use, it sounds good to go. Yes, you can pay for testing, and that is an extra cost, it's your call.
 

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I use 5/8" smooth steel rods and I cut them to 18" long. Problem is rebar will still bind, you don't want that. But the foam on the side should be good enough, just drill rebar into existing slab to tie those pours together. If you have expansion on sides, that will be enough and you can just tie all pours down the center if you have foam all around.

The smooth dowels would be for the sides to keep them from falling, it did them on all my edges but a lot of people thinks it's over kill. I just didn't want the edges to drop.
 

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Discussion Starter · #10 ·
Thanks! Yes foam along entire footing.. ok I will source smooth 5/8 rod and toe like that. That was thot was to prevent new slab from settling and leaving a lip. Thanks again!
 
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