No control joints in slab?

[Hobby_Man22]

Can these be placed 3 years later? It's a 30x50 and only has one very minor in the middle. It stopped once it hit the footing.

 

[ConCretin]

Not much value in cutting them at this point. The only purpose of control joints is to relieve tension from drying shrinkage by encouraging cracks you can't see to prevent cracks you can. A slab will continue to expand and contract with thermal changes over time but those stresses are less and the concrete has developed the tensile strength to resist cracking. In other words, if it ain't cracked yet it probably won't.

 

[nadogail]

My concrete guy gives two guarantees with every Slab he pours and finishes: 1, Nobody will steal your slab and 2, Your slab will crack.

 

[wssix99]

My concrete guy gives two guarantees with every Slab he pours and finishes: 1, Nobody will steal your slab and 2, Your slab will crack.

If you hire a skilled designer/engineer and get a concrete finisher who can follow instructions, you can be in control of #2 and won't have to settle for excuses in advance of the job.

 

[Walkers]

If you hire a skilled designer/engineer and get a concrete finisher who can follow instructions, you can be in control of #2 and won't have to settle for excuses in advance of the job.

Are either of them unicorns?

 

[WNYflyer]

Seeing that you are in Texas are you sure the slab isn't some type of post-tensioned slab?

 

[wssix99]

Are either of them unicorns?

lol Quite possibly.

 

[brownbagg]

My concrete guy gives two guarantees with every Slab he pours and finishes: 1, Nobody will steal your slab and 2, Your slab will crack.

and hes an idiot

 

[Worsedog]

I have yet to understand the insistence that all slabs will crack. I understand that many do, but I believe it's a factor of ****** base prep and improper curing.

My garage is a single monolithic slab on grade 30x40. It doesn't have a single control joint or crack.

Additionally the Home Cheapo down the street is a bunch of 30 or 40 foot square slabs and there's no cracks in them either.

 

[ConCretin]

It's entirely possible to construct a slab that won't crack..........up to a point. Concrete cracks in new slabs result from shrinkage and as the slab gets larger, the inevitability of a shrinkage crack increases. Cement content, aggregate type and size, the volume of mix water, etc. determine how much the concrete will shrink but the size and design of the slab determine if and when that shrinkage results in cracks.

Slab A is a 3000 psi mix with 1" aggregate, a water reducer and fiber mesh placed on a flat sub grade with a vapor barrier and with no obstacles to restrain it from contracting as it shrinks. Slab B is a 5000 psi mix with 3/4" aggregate, straight water mix and steel reinforcing placed on a crushed stone base with thickened edges. Slab A could be several times larger than Slab B before shrinkage cracks occurred and control joints were needed.

Honestly, If a never hear the old "two guarantee" thing again, I won't miss it. For an moderate sized residential garage slab, it's entirely possible to avoid cracks if you and your finisher are willing to put in the effort. Most people, including myself in most cases are content to cut a few control joints so we don't have to look at cracks if they happen.

 

[CraigStu]

Certainly it is possible to have a slab that doesn't crack. It just takes more effort. There are 3 new neighbor hoods being built in our town. They are still in the 'moving tons of dirt all over the place' stage. When I see how the original hills and valleys are changed into much flatter land I always wonder how it will work out. A lot of the houses will be built in what used to be valleys. If they lop off the high spots to fill them in, it seems to me that the standard theory of digging for your footers until you reach undisturbed soil is blown up. I know that there will be a lot of heavy equipment run over the whole area which will help compact the soil but I still think that I'd prefer my house be built on a shaved off hill rather than a filled in valley.

 

[jrsavoie]

My concrete guy gives two guarantees with every Slab he pours and finishes: 1, Nobody will steal your slab and 2, Your slab will crack.

I had somebody steal my dirt.

 

[joshmodelskidoo]

The control joints are the thinnest spots in concrete to control cracks correct? Run a grinder/saw over it and make some control joints if you like. I would assume that’s how it should be done anyway

 

[Yankee2bbq]

The control joints are the thinnest spots in concrete to control cracks correct? Run a grinder/saw over it and make some control joints if you like. I would assume that’s how it should be done anyway

No.

 

[brownbagg]

concrete cracks because of poor workmanship

 

[Hobby_Man22]

The control joints are the thinnest spots in concrete to control cracks correct? Run a grinder/saw over it and make some control joints if you like. I would assume that’s how it should be done anyway

So it controls it from the top? Doesn't it crack at the bottom too?

 

[joshmodelskidoo]

Yes but the control joints are only on top as far as I know. Im no contractor but i believe that’s how it works

 

[Dagny]

There are a lot of things that the cement man can not control.

 

[Michaelhoot]

Can these be placed 3 years later? It's a 30x50 and only has one very minor in the middle. It stopped once it hit the footing.

I have a 72 x 60 slab with no joints. I am in TX so we don't get the cold swing. Very few tiny cracks and has been a year.

 

[Hobby_Man22]

I have a 72 x 60 slab with no joints. I am in TX so we don't get the cold swing. Very few tiny cracks and has been a year.

I took a better look a few days ago. I have two cracks right down the middle, so the slab is essentially cracking in half. Hopefully this isn't going to be an issue.

 

[ConCretin]

I took a better look a few days ago. I have two cracks right down the middle, so the slab is essentially cracking in half. Hopefully this isn't going to be an issue.

Shrinkage cracks are nothing to worry about. Think of it this way. If you'd cut control joints originally, you'd have cracks you couldn't see and wouldn't worry about instead of cracks you can and do. The cracks themselves aren't any different other than random cracks happen wherever they feel like while control joints crack (hopefully) where you tell them to.

 

[Alchase]

Question for those who know, I have a 84”long 3 car driveway. It does have expansion joints cut both width wise and length wise down the middle.
I bought self leveling filler a few years ago, just have not got around to using it.

my question is do you recommend filling the expansion joints with self leveling filler?
I have heard both yes and no.