Below Slab Insulation In Tank

[KACELTD]

I am working on a project that has a cooling tank system that needs below grade slab insulation between reinforced slab and blinding (mud slab). The designer has specified 200 mm (4") STYROFOAM as the insulating material. My concern/questions

1. Given the load of water and slab, STYROFOAM will be compressed and may loose its insulation properties rendering it useless.
2. What other structurally sound materials could be used for insulation?
3. Will the compressed STYROFOAM still function as an insulation material?

Tank Dimensions: 7m x 21m and 2.8m deep below ground.
Slab thickness is 300 mm.
Tank is Located in the tropics.

 

[JAE]

A few links with possibly some relevant info:

http://www.epsindustry.org/

A table of various geofoam grades with compressive strengths:
Not sure what your total tank weight is but you could compare that pressure to the various grades here and see if any work. Use the compressive strength at 1% strain.

http://www.geofoam.com/downloads/brochure/Foam-Control-EPS-Geofoam-TechData.pdf

 

[JStephen]

Years ago, I remember reading of some freeway construction where they used big foam blocks instead of fill in order to reduce the dead load they were adding to the subgrade (on I-70 in Colorado). So presumably, there are styrofoam-type materails suitable for long-term loading and use.