Forklifts on Asphalt

[reddahaydn]

Hi All,

I have been asked by a client to design an asphalt surface for them to store containers and run a forklift over to move the containers.

The client (builder) suggested 70mm of asphalt minimum, with small aggregate.

Is this something any of you would have comfortable specifying? I'm not super confident with the long term prospect of asphalt under forklift type loads.

CBR of the site is 2.5%

Any advice or a direction where I could find further information would be appreciated.

Cheers,
Haydn

 

[racookpe1978]

Come on.

What temperature asphalt?
What loads under each tire (a small forklift tire might be only 4x2 "touching" surface under the front tires.
What is the asphalt laying on? And how much confidence do you have in whoever laid the parking lot?
What loads and how critical and how often are they moving?



(Phoenix in the summertime lifting 12,000 lb assemblies and loaded 8x8x40 foot containers?
Or upstate NY in the winter with the asphalt poured over loose gravel and old farmland lifting 400 lb pallets??

 

[civeng80]

I wouldn't recommend an asphalt pavement at all.
Within a year or so it would be at the stage of digging it out and placing a concrete pavement.
Better off biting the bullet and doing it now.

 

[DDBPE]

First, a 70 mm small aggregate surface course will not hold up to the loads from the forklifts. Small aggregate or surface mixes when used as the builder is suggesting is good for parking lots, not heavy loads and I would even question that with a low CBR value of 2.5. If they are moving containers, which could weigh 40,000 lbs, the loads on the tires of the forklift are tremendous especially when they are turning or stationary picking up or setting down the load.

I have worked at a wood preserving site where they take trainloads of lumber and pressure treat it. They use large forklifts over the predominately asphalt paved site, however, we go back every year and repair failing, high traffic areas (the owner is cheap and just wants it repaired for the season). The owner this past year decided to place concrete where the storage racks are to prevent the severe rutting that was happening when they pick up/set down the bundles. They also placed slabs in high traffic areas.

If asphalt is what they desire, you would need to start with a good sub-base material, and with a low CBR, maybe cement stabilized. From there, a base asphalt (top size aggregate 38.0 mm - 25.0 mm), possibly an intermediate layer (top size 19.0 mm), and then the surface course (top size 12.5 mm). Look at some of the design guidelines the FAA uses, there are many paved runways and planes impart a significant load on them. A recent project we competed had 8" sub-base, 8" P403 asphalt, and 6" P401 asphalt for a total cross section of asphalt of 14".

If I where the client, concrete would be the way to go (this is coming from someone who as one aspect of my job manages several asphalt plants and paving crews, just don't let my boss know). It might be a little more expensive now, but will pay in the long-run. If not, the client should expect to be repairing areas, if not every year, every other year.