CCIL CCIL - Canadian Council of Independent Laboratories Soil Testing and Geotechnical Analysis Questions and Answers 4

Question 1

Which ASTM standard governs the laboratory determination of the shrinkage limit of fine-grained soils?

Accepted Answer

ASTM D427

Answer

ASTM D427 covers the test method for shrinkage factors of soils by the mercury method, defining the shrinkage limit.

Question 2

In a consolidated-undrained (CU) triaxial test, pore pressure measurements are used to calculate which parameter?

Accepted Answer

Effective stress strength parameters (c' and φ')

Answer

CU tests with pore pressure measurement allow back-calculation of effective stress parameters c' and φ' from Mohr-Coulomb failure envelopes.

Question 3

According to ASTM D1556, what material is used as the filling medium in the sand cone density test?

Accepted Answer

Ottawa sand passing No. 20 and retained on No. 30 sieve

Answer

ASTM D1556 specifies Ottawa sand (or equivalent) passing the No. 20 sieve and retained on the No. 30 sieve for consistent cone calibration.

Question 4

What does the term 'sensitivity' refer to when describing cohesive soils?

Accepted Answer

Ratio of undisturbed to remolded undrained shear strength

Answer

Sensitivity (St) is the ratio of undisturbed peak undrained shear strength to remolded undrained shear strength at the same water content.

Question 5

Which sieve size defines the boundary between gravel and sand in the Unified Soil Classification System (USCS)?

Accepted Answer

No. 4 (4.75 mm)

Answer

The USCS uses the No. 4 sieve (4.75 mm opening) as the boundary between gravel and sand particle sizes.

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