Walkway expansion joints

[kneele00]

I'm adding 12' in length to an existing walkway. The current walkway has 1/2" expansion joints every 4' or so. This will be my first concrete work, so I have done a lot of research to prepare, but everything I have read just says to pour the walkway with rebar reinforcement running the whole length, then cut control joints. I would like the new walk to match the current walk, so I think I would like to place the expansion material between each 4' section.

How do I do this, and how do I reinforce the walkway section? Any recommendations?

Thanks a million, Kenn.

[Rich]

The downside to the 1/2" expansion joint every 4' is that each slab is independent of the next - which can make for rough walking. That being said - I realize that you want it to match. I would form the whole outside of the walk and put a 2x4 every 4' where you want the expansion material. Pour every other square, finish, etc. Strip the intermediate 2x4's then place your 1/2" expansion material against the concrete and pour the remaining squares.
For reinforcement you can run the rebar continually and cut the 2x4's and expansion material to go around it... or use fiber mesh in the concrete or welded wire mesh in each square. The continuous rebar will give a little more dependence from slab to slab but may rust and bleed up through the concrete - or it may not.. just depends on the circumstances.

[kneele00]

Thanks Rich for such a complete answer.

I have some wire mesh, and it also has some rust on it. Does the wire mesh ever cause rust spots to surface on the concrete or only rebar?

[Rich]

Not usually because it's most often pushed to the bottom of the pour where it doesn't do any good :)
Sorry.. couldn't resist. Honestly though - if you get it too close to the top of the concrete it will rust through. Just be careful to keep a minimum of 2" coverage over any rebar or mesh in the pour.
BTW - rust on rebar and mesh has been shown to provide better adhesion to concrete unless it's actually flaking off the steel. A little rust is nothing to worry about.

[mjpliv]

If the guys pouring the concrete are any good they will use a rake or hook to reach down into the concrete and pull the welded wire mesh a few inches up into the slab.

[Tom R]

But Rich, if I'm understanding you right, wouldn't that way require 'paying' for two separate deliveries. How about drilling holes thru the expansion joints at the 'height' of the rebar (with 'chairs'), prop everything in place at your 4' intervals, pour and pay once, and be done with it.

[Rich]

Yes it does require that there be 2 placements. The problem without pouring against a form is that the expansion material will move all over the place and rarely ever stays straight. You end up spending all your time fighting the expansion joint to keep it in line. It can be done if your concrete is phased correctly by putting the formwork in and ordering a low slump concrete finishing quickly - then removing the intermediates and pouring the rest. Like I said - finish quickly and it might turn out alright.
Honestly - unless it's 100' of walkway I wouldn't bother with a concrete order and just mix it on site - it's only 12'. :)

[Tom R]

Sorry Rich, I had to re-read it, I thought it said 120'. I didn't know we're only talkin' about 1/2 a yard. :oops:

[Rich]

No need to apologize.. you were right in the regards of 120'.