Geofoam under parking lot 2

[Imagineer]

Project: Snow Melting under parking lot and alleyway. The kicker is that occasionally a 15-ton crane to remove rooftop equipment, etc. sets up in the alleyway.

The manufacturers of the hydronic snow melt system require insulation under their tubing because the water table is within 8 feet. After some research, I've found that GeoFoam is used under highways, bridges, and abutments. This sounds like it might be the stuff to use. I've gone to several websites (geofoam.org, geofoam.com,

http://geofoam.syr.edu/,

and a couple of manufacturer's sites). Alas, I still don't have a good handle on this.


Has anyone used this under roadways? Is 10psi flexural strength really strong enough to support heavy vehicles?

Imagineer

 

[jdonville]

Imagineer,

Firstly, I gather that this is a forced/circulated warm fluid system that warms the pavement to melt snow and ice. Are the tubes embedded in or below the pavement? What are the tubes constructed of? Why does the location of the water table require the use of an insulating medium?

From what I understand, geofoam is quite literally foamed hydrocarbon (like styrofoam). It is extremely lightweight compared to traditional geotechnical materials (will more than likely float or provide a buoyant force when submerged).

You could also check out Elastizell (

http://www.elastizell.com).

The product is a foamed cement, can be manufactured in a variety of strengths and unit weights, and is cast in place - providing a monolithic final product.

Finally, you should probably get a geotech to assist you with the pavement design for the heavy loads, as there may be other considerations that you may not be aware of.

Jeff


Jeffrey T. Donville, PE
TTL Associates, Inc.

http://www.ttlassoc.com

 

[BigH]

Imagineer - geofoam (expanded polystyrene) is/has been extensively used many places. I know of a large 5km project in Malaysia where it was used. It was also used extensively in Utah's I-15 upgrade for winter games. Norway has used it for more than 25 years with no degradation. There are a few problems - flotation; combustibility, etc. but these can be handled. There are two "institutes" in the US for this - at Manhatten University and at Syracuse. Do a search on Dr. Horvath at Manhatten. He has issued, through some agency, a 800 page tome on the use of geofoam in highway construction. The principal design parameter really appears to be the deformation of the material but in general, a "design" compressive strength of 100kPa is used and that the loads should be in the range of 40 to 50% of this. Horvath states that you would "Choose permitted compressive stress to give less than 1% strain in rapid loading test (10% strain per minute)" There is a mountain of literature on the net for this but the Horvath Tome would be the best start.
Yesterday, I actually gave a presentation to the IIT-Kharagpur on the subject and I also covered Elastizell. This is a great product and is used extensively as insulation for roofing applications besides the civil engineering applications. I've used it before with great results.