Insulation material compressive strength test- Calcium Silicate (Medium Density)

[MKhaniba]

Can anyone provide me some info about how humidity can affect the compressive strength of insulation materials- Calcium Silicate (Medium density)?
What does it mean if cracks propagate during the compressive test?

 

[SWComposites]

If cracks propagate? It means the material is failed.

 

[3DDave]

Since the material gains strength from hydration I would expect the strength to be little affected by humidity. Since it is used as an insulating material and is porous by nature, humidity or water absorption will reduce the ability to insulate and, if the item being insulated raises in temperature above the boiling point of water, may fracture due to the pressure of steam formation.

As SWComposites mentioned, if it cracked as part of a test where it should not crack it failed. If the material is lower density than required or of an incorrect composition, those would be reasons for failing the test.

 

[MKhaniba]

Since the material gains strength from hydration I would expect the strength to be little affected by humidity. Since it is used as an insulating material and is porous by nature, humidity or water absorption will reduce the ability to insulate and, if the item being insulated raises in temperature above the boiling point of water, may fracture due to the pressure of steam formation.

As SWComposites mentioned, if it cracked as part of a test where it should not crack it failed. If the material is lower density than required or of an incorrect composition, those would be reasons for failing the test.

Thank you for your response. My concern is that although cracks propagated during the test, they did not appear to affect the load-displacement graph from the tensile tester. I observed no noticeable drop in the load on the graph. In this situation, would the test still be considered a failure?

 

[Gr8blu]

Would it still be a failure? Depends on why the material is used in the first place. If it was intended as a thermal barrier for some process equipment (piping, etc.), then yes.

Would you buy a NEW blanket with a hole or tear in it? Especially if it was right where you wanted to be kept warm?

 

[rb1957]

ok, dumb question ... why are you relying on the structural strength of "insulation" ?

if you're saying that the insulation is straining like the underlying structure, but it isn't considered as part of the structure (carrying load), then cracks in the insulation have more bearing on "does the insulation still perform (insulate) as advertised ?"

 

[Compositepro]

Platten presses with hot plattens use insulation with high compressive strength to insulate the hot plattens from the structure.

 

[dgeesaman]

ok, dumb question ... why are you relying on the structural strength of "insulation" ?

if you're saying that the insulation is straining like the underlying structure, but it isn't considered as part of the structure (carrying load), then cracks in the insulation have more bearing on "does the insulation still perform (insulate) as advertised ?"

There is a growing movement to consider certain kinds of insulation panels as a portion of the overall structure of stick built homes. This has been led by the insulation manufacturers. While nobody argues the insulation contributes to the structure, the reduction of the traditional structural elements due to the structural insulation panels is where heated disagreement exists. At best, the SIP-reliant designs lack long-term experience. Many argue they are fundamentally inferior and received their material certifications from testing labs that are not impartial. From my perspective, I now know to ask about the structural design of a new home and research this if I ever buy a home constructed with these materials.

I guess the fundamental questions are: 1) are the cracks stable, such that they will not grow any further? 2) has the strength-to-failure (e.g. storm loading) changed compared to virgin material? 3) have the insulation properties changed?

Looking at the SIP panels currently offered, I'm seeing sheets of solid material separated by a polystyrene or other foam material. It's clear to me that if the foam material is broken down, the panel loses significant strength - much like if an I-beam loses its web section.

David

 

[rb1957]

Well David, I think I agree with you.