Reinforcement in Concrete Curb & Gutter 1

[cab454]

I am a civil engineer working for a local municipality. As a part of our land development infrastructure requirements, we require rebar in all public curb and gutter sections. Generally, the requirement is three #4 bars located 3" from the bottom, and spaced evenly through the gutter pan. The City has recently been contested on this requirement from a developer who does not wish to install rebar in the curb & gutter. With that as a catalyst, I am researching this to ensure it is a good requirement and is providing inherent benefit to our infrastructure. I have long felt it provides a superior product and provides benefit to the infrastructure, but to be fair, this is mostly anecdotal. Does anyone have any technical data or opinions on this?

Attached is one of our curb & gutter details for reference.

 

[SWComposites]

Ask the developer for a 50 year warranty on the curbs and gutters against any form of cracking or deterioration, with an upfront bond.

 

[CarlB]

Does the state DOT also reinforce curbs & gutters?
Alaska DOT and Anchorage standards do not reinforce curbs and gutters. This is a locale subject to frost action. Proper concrete, subbase, and 10' contraction joints should result in durable long-lasting curbs. Reinforcing would serve to reduce crack widths, if conditions were to cause cracking. Reinforcing doesn't really affect flexural strength. There are similar conflicting opinions/standards on reinforcing sidewalks, typically not done here.

 

[cab454]

DOT does not require reinforcement, but 95% of their maitained roads are highways with no curb and gutter. And in DOT tyipcal fashion, the lanes are so wide they wouldn't have to worry about loads on the curb and gutters that do exist. We are in Mississippi so while there is some freeze/thaw, it is not as severe as other parts of the country.

Would fiber be a fair replacement for traditional rebar?

 

[JedClampett]

Developers are notorious for building infrastructure that's just good enough to last through their buildout. The day they sell the last property, they don't care if the roads, sidewalks, pipes, etc. crumble into dust. I mean, don't get me wrong, my company makes a lot of money replacing shoddy work from developers.
But a few #4's in a curb is doggone near free. The fact that they'd cheap out on that makes me wonder what else they're putting in. As a exercise, offer to review their other work vs. your standards if they eliminate the reinforcing.

 

[Pinwards]

Anecdotally, I've never seen reinforcement in Curb & Gutter in the western US (OR, ID, WA, AZ) anyway.

#

 

[CarlB]

Several references can be found in a web search. In a quick review, nearly a consensus that reinforcing not necessary.
Possible exception may be where curb is load bearing, say for valley gutter or rolled curb at driveways where vehicles traverse. That reinforcing does not necessarily improve strength, but any cracking is held together better.

The following link is one example. Note it addresses extruded/slip-form placement. Placing reinforcing is more complicated in that method.

https://www.concreteparking.org/curbs/construction.html

 

[cab454]

Good info.

CarlB, that seems to be what I have heard, as well. Being that most of these are for neighborhoods/subdivisions, they are definitely load bearing (e.g. garbage trucks, school buses, driveway access for houses). The developer is using a curb machine so that is why he is complaining about the rebar. It's less of a material-cost issue than it is an installation issue, but that is beside the point. I feel that it provides protection against cracking as well as tensile strength under loads.

The one caveat is that I am hearing fiber reinforcement may be an alternative that meets the City's needs while removing the installation issue for the Developer.

 

[CarlB]

I can't say about fiber substitution, but I see Texas DOT may allow fiber in lieu-

https://ftp.dot.state.tx.us/pub/txdot-info/cmd/cserve/standard/roadway/cccg21.pdf

 

[cab454]

That's a great reference. Thanks.