Freezer Slab Insulation - compressive strength
Freezer Slab Insulation - compressive strength
(OP)
I have spec'ed freezer slab insulation a couple times in the past and have talked to DOW about how they come up with their numbers.
There are two type of insulation - 30 psi and 45 psi
These numbers are the crushing strength at yield or a 10% deflection (whichever comes first). And using a safety factor of 5 that DOW provides they work out to allowables of 864 psf and 1296 psf, respectively. Which sounds like a lot for a uniform slab, but the problem I am running into is when you have a forklift or point load. Even a moderate forklift wheel will compress around 1600 psf when loaded. And that is already taking into consideration the 45 degree load path angle through the concrete slab above.
What is the appropriate design method for this insulation?
There are two type of insulation - 30 psi and 45 psi
These numbers are the crushing strength at yield or a 10% deflection (whichever comes first). And using a safety factor of 5 that DOW provides they work out to allowables of 864 psf and 1296 psf, respectively. Which sounds like a lot for a uniform slab, but the problem I am running into is when you have a forklift or point load. Even a moderate forklift wheel will compress around 1600 psf when loaded. And that is already taking into consideration the 45 degree load path angle through the concrete slab above.
What is the appropriate design method for this insulation?






RE: Freezer Slab Insulation - compressive strength
The 45 degree angle is the commonly accepted as the failure shear angle in concrete. Does this angle slacken as the load becomes less than the failure load? ie if a load of 1,000-lbs fails the slab, does a load of 500-lbs produce a 2:1 or shallower shear angle, thereby giving you more contact area beneath the slab.
RE: Freezer Slab Insulation - compressive strength
If the area is subjected to high freezing, then you should look at heating the soil. Insulation only goes so far.
Dik
RE: Freezer Slab Insulation - compressive strength
RE: Freezer Slab Insulation - compressive strength
RE: Freezer Slab Insulation - compressive strength
After talking with co-workers about it, that is what we decided to do. I used the criteria from the insulation cut-sheet of 10% deformation (@ 30 psi) to determine the actual deflection. I then used this deflection and my applied point load to figure out what beam length would result in that deflection. Then I used the length of beam to determine my area (conservative - actually acting as a two way slab). Then I used that area and my applied load to determine the applied force to compare to the 30 psi with the safety factor of 5.
RE: Freezer Slab Insulation - compressive strength
RE: Freezer Slab Insulation - compressive strength
RE: Freezer Slab Insulation - compressive strength
RE: Freezer Slab Insulation - compressive strength