Asphalt Pavement over Parking Structure 5

[Tom1975]

Hi guys,

I am new to this site, but it seems like a great resource and somewhere to bounce ideas off of. I do have a few questions regarding designing an asphalt pavement section over a proposed parking garage.

The city I am working in has standard asphalt section of 1.5" surface, 2.25" of binder, 8" of aggregate and a heavy duty section of 1.5" of surface, 2.5" of binder, and 10" of aggregate in standard street applications. These requirements were applied to the parking lot portion of my site. Per the owner's request to add parking, the architect has now proposed a concrete parking structure to be placed under a portion of the proposed asphalt lot that has both standard and heavy duty pavement sections. My intial thought would be that the structural burden of the pavement section could be transferred to the top slab of the parking structure. Due to my lack of experience in this application, I have a few questions.

1. Do I shrink the pavement section to the asphalt portion only (and use levelig binder between the two pavement sections)?

2. Do I have to introduce the stone layer (and maybe a soil sub-base layer to providing a "locking" mechanism between the stone and the concrete slab)?

3. Due to potential settlement concerns at the transition point between pavement on earth and pavement on garage, the client would like to prevent cracking with some type of joint. Is there such a thing as an asphaltic expansion/contraction joint?

Any help would be great. Thank you for your time and advice in advance.

 

[Ron]

I would not use the aggegate layer on top of a concrete layer.

You have a couple of options...

1. Use asphalt only on top of the concrete

2. Increase the concrete section to make the grades work out then use asphalt pavement up to and around the concrete.

 

[hokie66]

You can overlay the concrete roof slab of the parking structure with asphalt. No aggregate required. Or you can leave the concrete roof exposed. In either case, pay especial attention to making this deck watertight and well drained.

At the edge of the basement structure, you will need relieving slabs extending some distance onto the ground to prevent the differential settlement from causing a step in the surface. There will be cracks in the surface at both ends of the relieving slab, so you can make these straight by providing control joints, but there will always be a need for maintenance at these points.

 

[TDAA]

I would prefer Ron's #2 option.

This allows you to keep an eye on the concrete and does not have asphalt cracking at the edge. Just spec a sealer for the transition, and recommend maintenance of that sealer / joint.

 

[Tom1975]

Thank you all for your feedback. I appreciate it.

 

[Zambo]

I also like Ron's option #2, but would seriously consider adding hokkie66's relieving slab (I would call this a transition slab) This may still cause a crack at the asphalt end of the transition slab, but would avoid a future step at the joint between concrete and asphalt due to differential settlement.

There hasn't been much response to Tom1975's point 3. Here is a link to joint types available

http://www.bridgejoints.org.uk/jointtype.htm

For your purposes I would consider an asphaltic plug joint. The other mechanical joints are applicable for the greater movement ranges found in bridges.

 

[Ron]

Where I transition from a flexible pavement to a rigid pavement, I slope the rigid pavement edge face at a 60 degree angle toward the rigid mass. That way when traffic crosses the joint, it tends to push the asphalt into the concrete, helping to maintain a seal between the two.

 

[beej67]

That's a really neat idea Ron.

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