CCIL CCIL - Canadian Council of Independent Laboratories Soil Testing and Geotechnical Analysis Questions and Answers 2 — Questions and Answers
Question 1: Which ASTM standard covers the Modified Proctor compaction test used when higher compactive effort is required for subgrade evaluation?
- ASTM D1557 (Correct answer)
- ASTM D698
- ASTM D4253
- ASTM D2049
Correct answer: ASTM D1557
ASTM D1557 specifies the Modified Proctor test using a 10 lb hammer dropped 18 inches in 5 layers, simulating higher energy compaction.
Question 2: In a hydrometer analysis of fine-grained soils, what physical law governs the settling velocity of particles in suspension?
- Stokes' Law (Correct answer)
- Darcy's Law
- Bernoulli's Principle
- Henry's Law
Correct answer: Stokes' Law
Stokes' Law relates particle diameter to settling velocity in a viscous fluid, forming the theoretical basis for hydrometer analysis of silt and clay fractions.
Question 3: What is the purpose of the meniscus correction applied when reading a hydrometer during a particle-size analysis?
- To account for the curved water surface at the hydrometer stem (Correct answer)
- To correct for temperature variation in the water bath
- To adjust for dispersing agent concentration
- To normalize results to a standard specific gravity of solids
Correct answer: To account for the curved water surface at the hydrometer stem
Because the hydrometer stem is read at the top of the meniscus rather than the bottom, a meniscus correction is added to all readings.
Question 4: During field density testing with a nuclear density gauge, what type of radiation is used to measure soil moisture content?
- Neutron radiation from an Americium-Beryllium source (Correct answer)
- Gamma radiation from a Cesium-137 source
- Alpha radiation from a Radium source
- Beta radiation from a Strontium source
Correct answer: Neutron radiation from an Americium-Beryllium source
Neutron radiation from an Am-241/Be source interacts with hydrogen atoms in water molecules, allowing indirect measurement of soil moisture content.
Question 5: What AASHTO classification would a soil with a liquid limit of 45 and plasticity index of 20 most likely fall under?
- A-7-6 (Correct answer)
- A-4
- A-2-4
- A-6
Correct answer: A-7-6
A soil with LL > 41 and PI > 11, where PI > LL - 30, classifies as A-7-6, indicating a highly plastic clay poor for subgrade use.
Question 6: What is the CCIL Type I certification specifically designed for technicians performing?
- Soils and aggregates field testing and sampling (Correct answer)
- Concrete field testing and sampling
- Asphalt mix design and sampling
- Laboratory chemical analysis
Correct answer: Soils and aggregates field testing and sampling
CCIL Type I certification qualifies technicians to conduct field testing and sampling of soils and aggregates on construction projects.
CCIL CCIL - Canadian Council of Independent Laboratories Soil Testing and Geotechnical Analysis Questions and Answers 2
Which ASTM standard covers the Modified Proctor compaction test used when higher compactive effort is required for subgrade evaluation?