Crumb Rubber Question

[scitanul001]

We're looking to help out one of our clients. They have a waterline that is approximately 30" below finished grade. They are requesting a 3"-4" rigid insulation (about an R-3 insulation rating) material to be laid over the top after we excavate down to about 8"-12" above the water line. My question is; can anyone point me in a direction of obtaining an R value for 12" thick of crumb rubber? I need to quantify the R value to the client indicating that the crumb rubber will offer better insulation than the rigid insulation.

Thanks in advance for your responses.

 

[SlideRuleEra]

Looks like a reasonable value for the 12" thickness is R = 7.
See page 2 of "Civil Engineering Application of Tire Shreds" for the following

The thermal conductivity of tire shreds with a 3-in. maximum size is about 0.14 Btu/hr-ft-°F. This is seven times better than soil, which typically has a thermal conductivity of about 1 Btu/hr-ft-°F.

Here is the link to the document

http://www.shercomindustries.com/industries/Hilton%20Head.pdf

http://www.SlideRuleEra.net