Rebar Dowel Size and Spacing

[Idigguns]

I had to cut out a 6' piece of a 6' wide sidewalk 4" thick for some underground piping. Now I need to submit a shop drawing of how I'll replace it. I'll have a contractor friend do the work when the time comes, but he's in the hospital right now. I just need to submit a drawing so the Engineer can have something to start with. The sidewalk is in a court yard, so there's no vehicular traffic on it. I was thinking of putting #4 X 12" rebar dowels every 12" to tie the new sidewalk to the old. That would be about 5 on each side, sticking out 6". Does that sound good enough? Any other suggestions?

 

[csd72]

It is very hard to dowel into a 4" slab without cracking it, good luck!

 

[GeoPaveTraffic]

Most muncipal sidwalks have no reinforcement in them at all and when a section is replaced they are not tied together. Just sawcut the edges of the existing sidewalk, place a form, and place the concrete.

Not sure why anyone would want a shop drawing for that.

 

[Idigguns]

That's a good point. Maybe I can use a smaller size rebar.

 

[Idigguns]

This Engineer wants a shop drawing for everything. I guess I can submit a drawing with no dowels, and he can correct it as he sees fit. Thanks.

 

[RHTPE]

csd72 makes a very good point - it will be difficult to drill into the edge of a 4" slab without weakening or cracking it.

I would submit a sketch without dowels first.


Ralph
Structures Consulting
Northeast USA

 

[cvg]

steel reinforcement is needed in sidewalks, concentrate on the subgrade preparation and compaction as well as the required concrete strength. Recommend 90 - 95% compaction and class A (3,000 psi) concrete. You may also want to show joint filler between the old and new slab.

 

[cvg]

correction, I fat fingered that - steel reinforcement is "not needed" in sidewalks...

 

[dik]

You might want to sawcut the top 1" for a smooth line, and break the rest out and let the aggregate interlock hold the new concrete in place.

 

[hokie66]

If your piping installation has disturbed the ground sufficiently that settlement could be a problem, then the engineer may want to thicken the slab enough to install a bottom layer of reinforcing so that the slab spans across. Just give the "engineer" a plan and cross-section, showing the extent of the excavation, and he will tell you what to do.

 

[civilperson]

Just use a thickened edge, (or thicker slab), around the replacement slab. Try 6 inches deep throughout with WWF in the center.

 

[cvg]

wwf? still sounds like overkill for a pedestrian sidewalk that is nowhere near vehicular right of way... If you do a good job with compaction, you do not need steel. If you really feel the need for crack control, use fibers.

 

[chicopee]

#4 rebar for a sidewalk is excessive. Remembering the 1/8th inch rule you will be using a 1/2" dia. rebar. Instead use wiremesh if you still decide to reinforce with expansion joints on both ends.

 

[Bedrock1977]

A good equivalent to #4 @ 12" EW is 6x6 - w2.1/w2.1 Welded Wire Fabric (WWF). It typically is purchased in 8x15 sheets or sometimes longer rolls and depends on your local area.