Geo Foam Structural Fill

[D a v e W]

Does anyone have any experience with the usage of geo-foam structural fill?



I have a project that is proposing it as fill instead of importing soil. Our civil guys do not want it. I spoke with a geotech yesterday who had seen it used on a few project in the Seattle area with no issues.



Mostly I am seeking the negatives for the product.



Its usage is for under a driveway as fill against a retaining wall (2-4 feet), no dead load (surcharge) only live load as a vehicle passes over it. Flat work and retainer is exempt like this, however it is for a new SFR which required our civil side to review it.



Any input is appreciated!

 

[Paul Sweet]

There's an article on it in this month's Constructin Specifier: http://www.kenilworth.com/publications/cs/de/201008/54.html

The only time I've seen it used was when I was with a firm designing houses along the coast. They sometimes used it when the grade had to be built up but there was a deep stratum of highly compressible clay. It is outside prescriptive codes and needs to have a geotechnical engineer's recommendation.

 

[Uncle Bob]

Keep away from flame; and I have seen the stuff broken up when in contact with gasoline and water mixture.

Here's some information;

http://geofoam.syr.edu/GRC_FAQ.asp

They are going to use it anyway,

Uncle Bob

 

[Glennman CBO]

Sounds Awsome.

 

[Mark K]

Geofoam is used by state highway departments to support highways when the weight of fill would otherwise result in excessive settlement. It is considered acceptable practice if used correctly.

I would expect that even the lowest grade foam would have all the strength needed. If loads are high the foam will compress a little but likely no more than the fill would. Probably less.

The use of foam would likely reduce the forces on the retaining wall thus improving the factor of safety. It should also inprove drainage. It will not contribute to frost heave if the ground freezes.

High heat such as flame and gasoline can cause problems. Rats and gophers like to burro in it but then they also do this with soil. If either of these situations occur the owner is left to repair the damage but I do not see a safety problem.

I am a little surprised that it would be used for such a low retaining wall since it appears overkill, but I can see no problems with its use. Properly used it is considered a reasonable design option.

 

[conarb]

2603.8 Protection against termites. In areas where the probability of termite infestation is very heavy in accordance with Figure 2603.8, extruded and expanded polystyrene, polyisocyanurate and other foam plastics shall not be installed on the exterior face or under interior or exterior foundationwalls or slab foundations located below grade. The clearance between foam plastics installed above grade and exposed earth shall be at least 6 inches (152 mm).Exceptions:1. Buildings where the structural members of walls, floors, ceilings and roofs are entirely of noncombustible materials or preservative-treated wood.2. An approved method of protecting the foam plastic and structure from subterranean termite damage is provided.3. On the interior side of basement walls.

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If termites are going to eat it what good is it? Furthermore the environmentalists are death on Styrofoam, that garbage patch in the Pacific is twice the size of Texas, and you don't want those folks picketing your house.​

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