Concrete Slab repair

[lbhsbz]

I have a halfassed single car garage added onto the side of the real garage and evidently no rebar was used in the slab...from what I can see, it’s about 6” thick and has this big ass crack all the way through.

I know that the proper fix is to tear it all down and pour a new one, but that isn’t in the cards right now.

Mainly would just like to seal it up...if possible prevent further degradation, but I imagine if I add reinforcement, it’ll just crack elsewhere.

Thoughts from the concrete guys?

 

[ka0tyk]

my neighbor had a company drill and put this expanding foam stuff under his slab to lift it back up into place. was pretty cool to see it lift a giant slab.

 

[Rajobigguy]

Is it just separated or is it lifting? If it is just separated I would pour epoxy grout in there and call it good.

 

[lbhsbz]

Is it just separated or is it lifting? If it is just separated I would pour epoxy grout in there and call it good.

Not lifting much, if any...just separating.

 

[Go-Fly]

Concrete comes with three guaranties. It won't blow away in the wind, it won't burn and it's going to crack. That looks like a footing roll out.

 

[WYRD]

Structural grade foundation repair. I think sikaflex make some. Check your walls to make sure it's not pulling them apart or stressing them

 

[JDub24]

How is the structure above it look? I’m curious how it has separated that much with no other effects.

If all you want it cosmetic check out Sikaflex products. They make caulking specific for larger joints (sidewalk expansion joints) that is rated for outdoor use so it should do ok in your application.

As you already stated the best thing to do (in the future) is remove/replace it. But before you do that I would try and figure out why it happened in the first place. That’s a big ass crack.

 

[Yellowboat]

Not much you can do that wont cost more the a new slab. You could cut 2' out drill and epoxy in some pins, yie rebar to that and then pore it. But i doubt it is worth it. I thinkbi would just add hydrolic cement and be happy.

 

[JUSTWANNARACE]

Couple tubes of JB Weld should fix that right up!!

 

[nrbr]

I agree something more then just a concrete crack going on. But my quick temporary fix would be a couple tubes of Simpson set22 .

 

[Taboma]

Would seem they didn't pump enough sea water back in after they pumped all the oil out --- or too much ?

 

[NicPaus]

My Brothers garage same way. Once it starts raining it will move almost closed. Summer the Adobe dries out and it opens up just like your picture.

 

[lbhsbz]

I agree something more then just a concrete crack going on. But my quick temporary fix would be a couple tubes of Simpson set22 .

The crack is 2+ inches wide and about 6" deep running for 10 feet (it's only about 1/2" wide at the other end). I'd need a 5 gallon bucket of set22...at which point it would be cheaper to pour a new slab.

 

[lbhsbz]

My Brothers garage same way. Once it starts raining it will move almost closed. Summer the Adobe dries out and it opens up just like your picture.

It didn't close up much last year with all the rain we have...or it was full of saw dust, can't remember.

This particular lot is a bit strange...not the typical long beach clay...it's real sandy. My lot, and the ones on either side of me were evidently used as the "staging area" for all the materials when they built out the area back in '44. It depends where you dig...one spot you'll be in nice sandy loose dirt, move 10 feet and it's like a rock...move another 10 feet and its sandy again.

I'll talk to my tile guy tenant and have him bring over all the half empty bags of thinset and grout he has...

 

[RandyH]

The crack is 2+ inches wide and about 6" deep running for 10 feet (it's only about 1/2" wide at the other end). I'd need a 5 gallon bucket of set22...at which point it would be cheaper to pour a new slab.

Foam backer rod for the bulk, stuff it, then cap it with grout, trowel it smooth and move on.

 

[Mandelon]

How much work do you want to do? We do a few different methods depending on severity and budget.

If you are looking quick and cheap, Fill it up with a concrete patcher. Use a concrete adhesive on either side. This will most likely crack again.

Better fix would be to epoxy it. You can buy gallons of part A and B epoxy at various supply houses. It think HD Supply aka White Cap sells them. You can mix the epoxy with sand to stretch it. Sika Products SikaDur is the stuff. I forget which particular one, but perhaps check this: https://usa.sika.com/en/constructio...lti-purpose-epoxies/sikadur-31-hi-modgel.html This is a two parts, consistency of thick toothpaste. You mix it up with sand and pour it in. Finish with a wide plastic putty knife. Leave it high, then grind off with cup grinder. Its stinky but the concrete is likely to fail somewhere else before this stuff lets go.

Sutures are another good option. Sawcut and chip out in a perpendicular fashion across the gap every 24" or so maybe 3" deep. Then epoxy in rebar across the gap.

If you are going to get more serious many engineering reports will often have us cut back on either side of a larger crack about 18 to 24." remove the concrete. Dig out the soil down a foot. Replace with sand. Then dowel rebar into each side and epoxy rebar into place. Tie these together across the crack. Repour new concrete keyed under the existing slab on both sides. Use a diamond disk grinder for finishing smooth.

We have done this dozens of times with good results.

 

[lbhsbz]

Sutures are another good option. Sawcut and chip out in a perpendicular fashion across the gap every 24" or so maybe 3" deep. Then epoxy in rebar across the gap.

.

This thought crossed my mind....might try it. Thanks.

 

[Mandelon]

Or bend the sutures on the bottom so they are shaped like giant staples for even more holding power!

 

[lbhsbz]

Or bend the sutures on the bottom so they are shaped like giant staples for even more holding power!

That's even better than my idea of drilling holes on compound angles through both pieces from each direction

 

[Havasu blue label]

Put a couple of footings on the outside of structure below grade tie some strapes. Then fill that crack in garage

 

[Joker]

Don’t try to fill it with epoxy to hold it together. They will lose their properties after 1/4” and fail as the heat in mass becomes a weak point.

 

[rivermobster]

@Joker

 

[Rajobigguy]

Not lifting much, if any...just separating.

Philadelphia Resins Chock fast red, about $300 a unit and one unit will be way more than need.

 

[CoolCruzin]

That’s not a crack it’s a damn valley
Wow

 

[WYRD]

Grab a beer, and a tube, slap a garden hose in it and tube away

 

[4Waters]

The guy on TV swears by this stuff

 

[ElAzul]

Call your earthquake insurance guy

 

[FreeBird236]

Put a dozer blade against the outside of the foundation and push it back together.

 

[nrbr]

The crack is 2+ inches wide and about 6" deep running for 10 feet (it's only about 1/2" wide at the other end). I'd need a 5 gallon bucket of set22...at which point it would be cheaper to pour a new slab.

Oh hard to tell on phone screen. Yellow boat mentioned cutting a 2' trench , doweling and repour. That would be a cheap fix. Labor intensive but super cheap

 

[Classic Daycruiser]

Cu

I have a halfassed single car garage added onto the side of the real garage and evidently no rebar was used in the slab...from what I can see, it’s about 6” thick and has this big ass crack all the way through.

I know that the proper fix is to tear it all down and pour a new one, but that isn’t in the cards right now.

Mainly would just like to seal it up...if possible prevent further degradation, but I imagine if I add reinforcement, it’ll just crack elsewhere.

Thoughts from the concrete guys?
View attachment 816632

Cut out just enough with a small concrete saw to square it up, then re-pour. Should look great for another 10-25 years.