Drainage geocomposite

From the GMA Techline

Subject: Drainage geocomposite— I have to test drainage geocomposite material regarding friction behavior and internal shear strength. In terms of references, I see 2 options: friction test (drain material/soil), according to ASTM D5321; and internal shear strength, according to ASTM D5321.

I know that for friction test of drainage material, it is correct to test GCDs according to ASTM D5321. But I don’t know if it is correct for the request regarding internal shear strength of a drainage material, as I know that only for GCL is it required to know internal sheer strength, not for drainage material.

Please, could you confirm my accuracy? For a friction test of drainage material, is ASTM D5321 OK? For internal shear strength of drainage material, there is no test to execute. Only for a GCL is it possible to check internal shear strength. (Massimiliano, Italy)

Reply: You are completely correct. Internal shear strength applies only to GCLs.

In reality, you simply cannot fail a geonet internally, so it becomes a non-issue.

It seems to me that your engineer requesting such a test on a geonet composite is not up to speed with our technology.

Bob Koerner | GMA Techline