# Pouring a patio without rebar????



## luweee

I have a person thats bidding my patio pour. He claims to be a 40 + year union worker in concrete... seems really knowledgeable. But he says he doesnt use rebar in his concrete for reinforcement. He uses fibrous mesh instead?

will this do the job and last as long? is it a correct way of doing it?

Thanks


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## stadry

so far he's right but ask him about jnt pattern, slump, wtr/cement ratio, insurance, license,,, whether or not he's ' union ' doesn't mean much but not necessarily a minus, either,,, neither mesh NOR fiber mean much in a 4" patio.

' correct ' means 1 method & his is,,, more interested in the ' why ' of HIS thinking,,, that would tell me more,,, we rarely use either - why spend the $ for no appreciable benefit in this project ?

better he's got enough people on hand who know what they're doing w/o being told,,, hate seeing a crew 1 man short so its nec to ' bless ' the mud before it gets away from them & makes proper finishing almost impossible :furious: 

btw, sawing a proper jnt pattern at the correct time does more to eliminate random cracking in your conc than anything else :thumbsup:


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## PaliBob

Excellent advice in Post #2 from a Pro




luweee said:


> ......will this do the job and last as long?....


City sidewalks and curbs do NOT have rebar. 
.


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## posylane

I can't answer about the fiber since I don't know what he is actually using.

Metal mesh is junk. It will rust out in a few years (since it is thin) and won't be effective. Rebar is thick and will last a long time.

In Dallas sidewalks and curbs have rebar.

I don't think a decent fiber mesh will be as cheap as rebar. I'd ask him to provide the exact product name and then go research it. I have used fiber in all my hand done concrete (40 yards) but it is short (1" or so) loose fiber you put in the concrete as it is mixing. It is good stuff - I made 4" x 4" x 4' triangular concrete peices with just the fiber and you can pick them up in the middle and they won't break.

But I'd never substitute that for rebar on a patio - you want that to last a long time.


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## jlc791

I widened my driveway four years ago and poured 5" of fiberglass reinforced concrete at the recommendation of the concrete supplier. Only slightly more $$ than without the fiber but a lot cheaper - and faster - then setting up rebar. Not a single crack to date. 

jlc


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## joed

Never used rebar in a patio.


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## posylane

Unless you are looking to spend as little money as possible or don't care about unconrolled cracking, I don't know why you wouldn't use rebar. If you don't use rebar (and you are using regular concrete) you are likely to get more and bigger cracks, and sections of the slab could crack/break and fall in relation to the rest of the slab.

Bad thinks like this are not certain to happen, depending on your ground, plants/trees near the work, ect., but you are opening the door. Rebar is cheep. A bad job is expensive.


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## Yoyizit

http://en.wikipedia.org/wiki/Carbon_grid


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## jomama45

posylane said:


> Rebar is cheep. A bad job is expensive.


 
I couldn't agree more with this. As of this point in time, I haven't discovered a way to retro-fit steel re-enforcement into concrete, so I stick to putting it in right away. As a professional, the minor cost of 3/8" rebar, and minimal labor to handle install it, is a meager few percentage of the cost of an entire job.

The transition to "Fibermesh" to replace all steel was made here 15 years ago. Ironically, every reputable contractor in my area has gone back to sttel re-enforcement in the last few years. If they didn't revert, the odds are that they wouldn't make it in business in this trade. The fiber has little to no effect in holding separate slabs together in my experience, which is a big deal when pouring over expansive soils that are subject to 4' of frost in the winter.

Now, this is just how we construct here in a cold climate with these soils, but I can honestly not see fibermesh having any long term advantages to steel. The advantage is a little cost savings at the time of installation due to slightly cheaper material & labor costs.


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## kwikfishron

I couldn’t agree with posy lane and 45 more. Bar is cheap, what 4-5 bucks a stick?

OP never said how big the patio was but what, 20, 40, 60 bucks of bar and 30 min. of labor for peace of mind?

The entry to the 100 + year old home I’m in now (who knows when the Crete was poured) has a 5’x25+’x 6”+ thick wrap around concrete porch, broke in two places with 1 ½” gap at the top on hard clay soil. I look at it and think, if only there were a few sticks of bar in there.

Half of what I do in my business isn’t required, but I do it.


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## Tscarborough

Rebar does not prevent cracking in concrete. It holds the peices together, but that is not why it is there, it is there to increase flexural strength, which is not likely to apply to a patio unless you are in the habit of driving dumptrucks over it on a regular basis.

If your soils are extremely expansive (like Dallas), it is a good idea to use both Fibermesh (a brand name) and rebar. Poly fibers are not arranged in a mesh, they are chopped and distributed randomly through the concrete. They increase impact resistance and microcracking, as well as flexural strength.

All concrete cracks, the best you can do is to convice it to crack where you want it to, i.e. control joints.


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## stadry

'scar, they have ears but do not listen,,, they also have eyes but do not see :laughing:

adding bar at a d/w throat makes sense due to ' moment loading ' while its not needed 4' in from the st as the load's dynamic ( rolling ) & weighs less than if static ( parked ),,, using dble mats on a bdge makes sense yet senseless in a patio,,, conc usually cracks due to: 1, an improper jnt pattern; 2, early loading; 3, heavier-than-designed-to-support static/dynamic loads; OR 4, expansive soils.

when all's said & done, nothing beats thicker concrete :thumbup:


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## NJ Brickie

I also think rebar in a patio is usually not needed. With the soil in my area I only put rebar in patio/sidewalks (I know I am not suppose to put rebar in a sidewalk on city property) when there is a tree near by. Over the years the tree roots will lift the concrete and create a crack with separation of the two pieces. A stick or two of rebar will help to hold the two pieces together and hopefully you will have an arch to your sidewalk and not a tripping hazard. Tscar is right, rebar will not help prevent regular cracks in concrete that will eventually happen.


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## Red Squirrel

I'm no expert, but I think when it comes to non structural cement (it's just lying on the ground, it's not actually holding anything per say) the ground below is what is really important. It should be very well packed, and I'm sure there's proper processes and backfill materials that need to be used. I've seen people dig as deep as 4 feet to prepare the ground for interlocking stones so they don't buck and the ground does not shift under them. Similar should probably be done for a very good cement pour.


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## PaliBob

Two Thousand year old Concrete Dome
NO Rebar


http://en.wikipedia.org/wiki/Pantheon,_Rome
.


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## hereslookingatU

Hi

Concrete is excellent in compression but useless in tension - steel reinforcement is used to provide strength in the tension zone of the concrete (area nearest the ground). Fibre possibly has some benefits but it is more likely to be in the ease of pouring but this will not stop the concrete cracking as the fibres may well stretch a little bit but the concrete will not and it will fracture.

The reason steel reinforcement corrodes is generally down to there being an insufficient cover of concrete to protect the steel, minimum cover in exposed conditions should be 2" below and 2" above the steel mesh reinforcement, which really blows a hole in having a 4" slab - need to go to a 6" slab as the reinforcement needs to be in the tensile zone and not the middle thickness (neutral zone) of the slab! If your going to go the whole hog you should have a sub-base of 4" of clean hardcore topped with aprox. 2" of compacted sand blindng.

Steel mesh(fabric) generally comes in 8ft x 16ft sheets and it is down to the builder to cut it to size on site, any overlaps should be a minimum of 14" and steel ties should be used - guage of the steel should be minimum of 3/8" diameter. You will need to space the mesh off the sand blinding by 2" and pieces of clean hardcore can be used for this purpose.

One other thing - do not over-tamp the concrete - if you do you will get what is called a 'fatty layer' develop on the surface and this may lead to surface fracturing later on!

Hope the above is of some assistance and good luck with your project

Regards


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## stadry

never thought we'd be approaching ' zen concrete ' in this thread :laughing:

nevertheless, steel in slab reinforcement still adds only flexural strength ( bdge, elevated slab, hi-rise floors, moment loading, etc,,, in slab-on-grade, it does add strength during extreme tension stress ( green conc ) yet more benefit will be derived from placing contraction jnts in the proper pattern & in a timely fashion 

impo, adding fiber's like women watching oprah - they only FEEL better & nothing's resolved :yes: steel corrodes because the conc isn't waterproof ( either according to aci specs OR no proper waterproofing coating applied,,, 2" cover rule's rarely observed especially when you have jabonies or gollywops tramping all thru the mud,,, never have seen 3/8" welded wire mesh even on hgwys, aprons, 3,000,000 gal tanks, or runways


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## jomama45

itsreallyconc said:


> never thought we'd be approaching ' zen concrete ' in this thread :laughing:
> 
> Why not, isn't that how it always goes here? :laughing:
> 
> nevertheless, steel in slab reinforcement still adds only flexural strength ( bdge, elevated slab, hi-rise floors, moment loading, etc,,, in slab-on-grade, it does add strength during extreme tension stress ( green conc ) yet more benefit will be derived from placing contraction jnts in the proper pattern & in a timely fashion
> 
> I'd actually set proper curing as a higher priority than the jointing. If the compressive strength gains stay ahead of the tensile stresses, far less chance of random cracking. Better yet, skip the sawing & tool the joints in right away...... :whistling2:
> 
> impo, adding fiber's like women watching oprah - they only FEEL better & nothing's resolved :yes:
> 
> I won't advocate mush for plastic fibers either, I really don't put much faith into them.
> 
> steel corrodes because the conc isn't waterproof ( either according to aci specs OR no proper waterproofing coating applied,,, 2" cover rule's rarely observed especially when you have jabonies or gollywops tramping all thru the mud,,,
> 
> Don't forget that there is one very important element needed for steel to corrode: Oxygen. Steel encased in concrete doesn't see much oxygen at all. As a matter of fact, I'm often time amazed to tear-out out concrete that's 40+ years old and has steel mesh in it that is less rusty than the mesh I can buy new today. The only place I see steel fail regularily in res. work is at the joints, especially those that have opened substantially through time. This is one reason (among many others) why I opt for 3/8" rebar vs. mesh : longer lifespan at joints.
> 
> never have seen 3/8" welded wire mesh even on hgwys, aprons, 3,000,000 gal tanks, or runways


Myself either, I think he may have meant 6x6x6ga. WWM? AKA roadmesh.


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## hereslookingatU

Hi

Got my conversion wrong - working in metric converting to imperial in the head! 
Should have been 1/4" (6mm)

Regards to all!


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## posylane

In the Dallas metroplex, homebuilders own new subdivisions while they are being built, including the streets and sidewalks.

Of course the home builder would like to put /mesh in the sidewalks, but since the city knows they will inherit them, the force the homebuilders to put in rebar.

Guess what goes in the driveways? Mesh. Since the city is not responsible for your driveway, they are ok with mesh. Since they are responsible for the sidewalk, they require rebar.

I know this because I baught the leftover rebar from a homebuilder in a new subdivision and he explained how he had extra rebar lying around.

What does the city know?


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## stadry

VERY interesting question,,, don't the best & brightest always work for government ? ? ? my guess isn't compressive strength but tension ! ! ! is there much frost down there ? ? ? what do i win for being 1st & rightest ? ? ? :laughing:


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## joed

Someone on city council owns the rebar company.


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## Willie T

Yeah, ya can't go wrong following the city's example.:laughing:  :laughing: :whistling2:

Recently in our city they have been putting in crosswalks and speed bumps with a surface of that decorative brick veneer... about .5" thick. Should last maybe two years. Think someone's nephew owns the company?


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