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

According to ASTM D422, what is the standard sieve size used to separate coarse and fine fractions during a mechanical sieve analysis of soil?

Answer: No. 4 (4.75 mm)

The No. 4 (4.75 mm) sieve is the standard dividing line between coarse and fine fractions in a mechanical sieve analysis per ASTM D422.

Which ASTM standard governs the determination of the Liquid Limit of soils using the Casagrande device?

Answer: ASTM D4318

ASTM D4318 covers the standard test methods for Liquid Limit, Plastic Limit, and Plasticity Index of soils.

In the USCS soil classification system, what group symbol designates a well-graded gravel with little or no fines?

Answer: GW

GW designates a well-graded gravel meeting specific Cu and Cc criteria with less than 5% passing the No. 200 sieve.

What parameter is calculated as the ratio of the coefficient of uniformity (Cu) threshold check during USCS classification of gravels?

Answer: Cu ≥ 4 and 1 ≤ Cc ≤ 3

For GW classification, gravels must have Cu ≥ 4 and the coefficient of curvature Cc between 1 and 3.

During a standard Proctor compaction test (ASTM D698), how many layers of soil are compacted into the mold?

Answer: 3 layers

ASTM D698 specifies compacting soil in 3 equal layers using a 5.5 lb hammer dropped 12 inches, with 25 blows per layer.

What does a Plasticity Index (PI) of zero indicate about a soil sample?

Answer: The soil is non-plastic and has no range between liquid and plastic limits

A PI of zero means the liquid limit equals the plastic limit, indicating the soil transitions directly from semi-solid to liquid with no plastic range.