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-   -   rebar in concrete walkway (http://www.diychatroom.com/f19/rebar-concrete-walkway-83993/)

amakarevic 10-15-2010 01:33 PM

rebar in concrete walkway
 
i am building a concrete walkway (outside) about 30 ft long by 3 ft wide, was wondering if i should use rebar to reinforce it?

thanks

concretemasonry 10-15-2010 01:51 PM

Not necessary unless you are abnormally thin on the slab thickness. Just make sure you have joints to break up the 30' length.

Dick

amakarevic 10-15-2010 05:40 PM

joints for sure every 4 ft, i'd say. thank you, Dick !

jomama45 10-16-2010 07:22 AM

I generally agree with Dick, but I'd personally put 2 light (3/8") rods in the slab running paralell for the length. Nothing is needed across the width. These rod will merely asssist in helping keep the individual slabs at the same elevation through time. We can't always tell what kind of forces may be present under the sidewalk at installation (ie: frost, tree roots, tunneling) but the rod just gives the walk some "flexibility." It's money well invest IMO.

As for joint spacing, 4' is good, 4'6" is about the max. I would go.

itsreallyconc 10-17-2010 07:11 AM

dick & jo - rebar in a 4" sidewalk ? ? ? sure, contraction jnts & maybe expansion jnt up against the porch/driveway on either end but rebar ? ? ?

we wouldn't even use wire mesh - what did i miss here ?

thanks, guys

concretemasonry 10-17-2010 08:03 AM

Frost can do a job and crate trip hazards if there is differential settlement/heaving. It is not for strength, but continuity.

No code says this, but many people do it for good practice.

Dick

jomama45 10-17-2010 08:17 AM

Quote:

Originally Posted by itsreallyconc (Post 518240)
dick & jo - rebar in a 4" sidewalk ? ? ? sure, contraction jnts & maybe expansion jnt up against the porch/driveway on either end but rebar ? ? ?

we wouldn't even use wire mesh - what did i miss here ?

thanks, guys

My costs:
2 - #3 rods continuous for length of sidewalk = 60' or 3 -20' rods @ ~$3.00 a stick = about $9.00 to double, or even triple' the service life of the sidewalk. Not a bad idea to me, nor a waste of money. Having total disregard for future settlement, tree roots, utility trench settlement, etc.... is ignorant IMO. Of course every region is different, but I can honestly say if I didn't rely on steel reinforcement in my slab on grade poursw HERE IN MY MARKET, I'd be struggling to stay in business in this economy.


Quote:

Originally Posted by concretemasonry (Post 518248)
Frost can do a job and crate trip hazards if there is differential settlement/heaving. It is not for strength, but continuity.

No code says this, but many people do it for good practice.

Dick

That's exactly it, controlled lab tests don't take into consideration elements that vary in nature. They really are just "blanket" specifications that certainly weren't designed with the competive residential construction market in mind.

itsreallyconc 10-17-2010 08:31 AM

appreciate the responses - guess i've been out of the cold nawth too long :laughing: then again, we routinely make repairs where the orig steel/mesh was placed incorrectly - eg, in a 4" slab, even aci won't spec steel,,, then again, NYSDOT used to incl welded wire in sidewalks - they probably still do.

we use it in driveway throats & approach slabs but make thickness 6" & never cross jnts,,, heat expands conc greatly down here

concretemasonry 10-17-2010 01:10 PM

In northern Michigan I put in a driveway and use 4500 psi, aire entrained with fibers and wire mesh.

At the sidewalk and apron, both on city property, I could not use any rebar or wire mesh by code and city ordinance.

It was 5 feet down through sugar sand to rock. The frost depth was officially 4' but most people went for 5' on any structure if it was theirs. All utilities were above the rock and possibly subjected to freezing if there was not much snow cover. The aprons were usually not snow covered, so that is where freezing and damage was. In order to make repairs quickly and easier, the elimination of steel was a necessity. I got away with using the same "super" mix of concrete on the sidewalk section and the apron. We also had to leave a trickle of water running at a problem faucet or the lowest faucet to prevent the lines from freezing and our water rates were reduced during the cold months.

Every area has different problems and conditions, depending on the weather and geological conditions. Further north and west of me, there was more soil over the rock, so the utilities were lower and normal practice with steel was used.

Dick


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