Everyone can guide to correct for rubber membrane in CU triaxial test. The diameter specimen is 38mm, height to diameter ratio is 2. The thickness rubber membranes is 0.012''. I don't know to choose Young’s modulus suitable value.
Ron - remember that MIT or Harvard (can't remember which) actually carried out tests on the "best" rubber membranes - back in the early 1970s? Trojans came in first!