Bearing Capacity/Pressure of Existing Asphalt
Bearing Capacity/Pressure of Existing Asphalt
(OP)
What is a reasonable estimated bearing capacity/pressure of existing asphalt?
I must design the foundation for construction trailers that are being considered as a permanent commercial building that must be submitted for state approval.
The client wants to use 20-30" diameter x 8" thick concrete pole pads (cookies) for footings bearing on existing asphalt. I realize the bearing pressure cannot exceed the sub-grade soil capacity. I also realize i must use reasonable judgement regarding the condition of the existing asphalt.
Thank you!
I must design the foundation for construction trailers that are being considered as a permanent commercial building that must be submitted for state approval.
The client wants to use 20-30" diameter x 8" thick concrete pole pads (cookies) for footings bearing on existing asphalt. I realize the bearing pressure cannot exceed the sub-grade soil capacity. I also realize i must use reasonable judgement regarding the condition of the existing asphalt.
Thank you!






RE: Bearing Capacity/Pressure of Existing Asphalt
A construction trailer has to be tied down to keep it from blowing away....its gravity load is small, both dead and live.
Since you have small pads to distribute the load, the contact stress on the asphalt is going to be very low. Compare that to a tire load for a typical truck that might be used to deliver these trailers and you'll see that the contact stress for the tire might be on the order of 100 psi. Assuming you have at least 4 of the "cookies", with a combined area of 1256 sq. in., your trailer could weigh up to 125,000 lbs. and not exceed the equivalent contact stress.
In short....that asphalt pavement will likely carry a lot more load than you're going to put on it with those trailers.
RE: Bearing Capacity/Pressure of Existing Asphalt
I have the tie down issue taken care of with acceptable, data-provided, minute-man anchors.
The client is constructing combined trailer units with point loads of up to 26 kips.
Ron, I appreciate your time and input, but, the state inspector will not accept the reasoning that the asphalt pavement will "likely" carry...
Therefore, my questions remains:
What is a reasonable estimated bearing capacity/pressure of existing asphalt?
Thank you!
RE: Bearing Capacity/Pressure of Existing Asphalt
RE: Bearing Capacity/Pressure of Existing Asphalt
Regarding the bearing capacity, the prepared wearing + base courses should be much denser than plain ol' dirt. What are the typical soil bearing pressures for your region? The pavement should be at least that strong. Here in Florida, the soil allowable bearing capacity is usually 1 - 2 ksf (sandy soils). I'd raise questions about a 3ksf capacity -- here. Your region may quite be different.
As CVG suggested, review the geotechnical data, or consult with a geotech engineer on this. Often, they can provide testing for the _in-situ_ capacity.
Best regards, RAF
RE: Bearing Capacity/Pressure of Existing Asphalt
RE: Bearing Capacity/Pressure of Existing Asphalt
I understand that such inspectors don't necessarily apply reason to their requirements or interpretation. Your 3000 psf is achievable even in clean sands. The pavement layer just serves to buffer the loading on the soil even more.
RE: Bearing Capacity/Pressure of Existing Asphalt
I don't know how you can quantify that.
RE: Bearing Capacity/Pressure of Existing Asphalt
Weathered asphalt has a much lower tendency to creep than newer asphalt.