Foam Below A Driving Surface

[bigmig]

Does anyone here have experience using foam as a "filler" below a driving surface? I have heard of civil's using "geofoam" below roadways, and I have used it behind retaining walls (I'm a structural engr). I'm trying to spec a tapered foam mat that would underlay a residential house garage slab (4" thick). It would need to withstand pressures on the range of 150 psi. Any names of foam manufacturers would help. I'm going to google next, but thought I'd start here. Thanks.

 

[civilperson]

100 psi is the strongest compressive strength foam that I have specified, (under a foundation for a 500 kip transformer). I suggest calling the manufacturers to see if a higher rated foam can be produced.

 

[bimr]

Here is a manufacturer and some links:

http://www.geofoam.com/

http://www.softoria.com/institute/geofoam/index.html

http://en.wikipedia.org/wiki/Geofoam

 

[HB2U]

I'm not a structural engineer, but how did you decide that 150 psi is what the foam itself needed to be able to handle?

The construciton details that I've seen for insulated garage floor slabs just spec out EPS foam sheets. You can stack them to get the thickness that you require. The concrete slab over the top is taken to be the structural portion of the assembly. The only consideration I can think that you would need is to have a bit extra concrete handy s that if the foam compacts under the weight of the concrete, you can add a little more to acheive the surface elevation that you desire.

Is there some special use that drives the requirements?

If you need specs on the foam used in highway applications, check the web sites of some of the northern state's Dept of Transportaion web sites to see if they have their construction specs available on-line.

Good Luck.

HB