×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Rebar Dowel Size and Spacing

Rebar Dowel Size and Spacing

Rebar Dowel Size and Spacing

(OP)
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?

RE: Rebar Dowel Size and Spacing

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

RE: Rebar Dowel Size and Spacing

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.

RE: Rebar Dowel Size and Spacing

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

RE: Rebar Dowel Size and Spacing

(OP)
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.

RE: Rebar Dowel Size and Spacing


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

RE: Rebar Dowel Size and Spacing

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.

RE: Rebar Dowel Size and Spacing

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

RE: Rebar Dowel Size and Spacing

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.

RE: Rebar Dowel Size and Spacing

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.

RE: Rebar Dowel Size and Spacing

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

RE: Rebar Dowel Size and Spacing

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.

RE: Rebar Dowel Size and Spacing

#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.

 

RE: Rebar Dowel Size and Spacing

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.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources