Concrete Pan Reinforcement

[civilman72]

We are designing a large truck delivery parking lot re-paving project and are adding a 12' wide concrete pan to replace a small portion of the existing asphalt. The geotech pavement resurfacing options are: (1) 11" of asphalt on 12" stabilized subgrade or (2) an 11" concrete section with 12" SS. The Client has selected the asphalt section, and I'm assuming the concrete pan needs to meet the recommended concrete section. A few other items to note:

(1) I've typically designed 6" thick concrete pans and never spec'd reinforcement
(2) The typical DOT section is 6" thick and does not include reinforcement
(3) The geotech report does not mention the need for reinforcement, but they could consider this a responsibility of the civil/structural engineer

Would concrete reinforcement normally be included for this application (thicker section and heavy-truck traffic)?

 

[SlideRuleEra]

Would concrete reinforcement normally be included for this application (thicker section and heavy-truck traffic)?

Yes, the trucks can twist and turn in any direction. Loading is more or less unpredictable. For situations like this we used a minimum design of 12" thick, 4000 psi concrete with #4 bars @ 12", each way, top and bottom. Depending on soil conditions, dowels at joints may be appropriate, too.

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[dik]

You might consider 15M (#5) at 16 or 18 o/c... it's easier to place and walk on (through?).

Dik

 

[civilman72]

Thanks guys. I just spoke with the geotech and they stated they actually avoid recommending reinforcement, even in thicker concrete sections, unless it's on a major highway. They said they've seen too many issues with rebar here in the harsher environments of Colorado. I'll try to do some more research, and meanwhile any additional comments would be appreciated.

 

[thaidavid40]

Most tank trail turning pads on Army training ranges are thick, unreinforced concrete sections. Normally, only S&T steel is provided, though they may also have steel fibers to toughen the surface additionally against treads wear.
Dave

Thaidavid

 

[SteynvW]

We have recently moved to plastic fiber reinforced concrete for hard stands where trucks are
turning and so far so good. (and its easy to place).

 

[dik]

SteynvW:

You may want to re-evaluate the use of plastic fibres; they provide little added strength except in their control of bleed water.

Dik

 

[SteynvW]

The jury is still out on the micro-fibres, they claim it helps with plastic shrinkage and increased abrasion resistance, but perhaps the hard-stands would've been just fine without them.