Case Information wanted- Geofoam Support of Bldg.

[oldestguy]

Hi to you experts:

I am working with a geotech who is considering recommending a Geofoam substitution for some earth over very soft ground and then place a building on the foam. The object is to remove an earth load of 1,000 psf and then have about 1,000 psf available for a reinforced slab supporting a building. Building will be a three story apartment structure.

Can anyone point to some cases where this has been use for building structural support? The idea sounds good, but what has the experience been?

 

[BigH]

Oldestguy - I don't know of a building that has been supported on geofoam but I am aware of railroad bridge abutments that have (Scandanavia) -

http://www.softoria.com/institute/geofoam/applications.html#69

I'll try to find the original reference over the course of the next day; I think I have it since I put together a presentation on the use of lightweight fills in embankment construction.
Another concept that you may try - although more expensive, would be the use of Elastizell - it is a lightweight foamed cement - weighs about 30pcf but has the strength of 100psi or more. Might be too expensive for building - usually used in highway work. Why not put in a basement? - if he has to dig it out anyway - and make a floating foundation - the building would get "space".

 

[oldestguy]

BigH:

The foam support is one of the options and yes, a basement might be one. For some reason they don't need a basement or a crawl space.

There is a similar building in the area with heavily reinforced perimeter walls which appears to have no problems.

One option is a heavily reinforced slab on grade and no special underground treatment. Calculations for that settlement are planned, but insufficient site info places some question on current settlement estimates based on penetrometer, moisture content and zero blow count. My main concern is the utility connections and maybe sidewalk sloping wrong way, etc.

It is for a three story apartment building, brick exterior.

There appears to be plenty of scoop on using foam for highway fills, but none that I can find on structures.

 

[Ron]

OG...haven't used for buildings, but like others have done so for roadway (paper mill access road in tidal swamp). Also used it for cavity fill to support deteriorating falsework for "rock" structures at one of those "major theme parks". In that one, had to develop a special mix design to keep unit weight even lower than normal.

 

[moe333]

Oldestguy, there were projects completed using geofoam to mitigate new building settlement in Vancouver, BC (I think it was actually in a suburb of Vancouver) in the mid 90's. 5'-10' of old surface fill was removed and replaced with geofoam. Soft materials may have been 10'-20' below foundation level. I recall one paper written for the project by Brian W. Wilson and Brian E. Hall but have not been able to locate it through Google. I'm not sure if this type of work is still being done up there.