Rigid Insulation Compressive Strength

[JohnnnyBoy]

All,

A client of mine is asking me to specify the strength of rigid insulation to be used under a slab. In the specification sheet that I got from the supplier, specifies 40, 60, and 100 psi for compressive strengths. I should mention this will be a 6" slab with 10M at 12" c/c and will be taking loads from loading and unloading of vehicles in certain areas. To go about this problem I could grab an assumed wheel load from the intended vehicles and go through a pavement design, check deflection of the pavement (assuming the rigid insulation has negligible strength compared to concrete) and see if the insulation will crack/fail although this seems very complicated for a simple question like this.

Does anyone have a general rule of thumb for specifying rigid insulation.

Thanks,

 

[DETstru]

I specify EPS29.
Expanded polystyrene with 10.9 PSI compressive resistance at 1% elastic deformation.

ASTM D6817 covers this material.

Here's a cut sheet of a typical product:

https://www.achfoam.com/ACH/media/ACH/docs/Geofoam/Foam-Control-Geofoam-Tech-Data.pdf

 

[Canuck65]

There is a design guide on the Dow website for their HighLoad 40/60/100 insulation