CPII Materials & Testing 3 — Questions and Answers
Question 1: Which test method is used to determine the air content of freshly mixed concrete by the pressure method?
- ASTM C231 (Correct answer)
- ASTM C173
- ASTM C138
- ASTM C1064
Correct answer: ASTM C231
ASTM C231 covers the pressure meter method for measuring air content in freshly mixed concrete.
Question 2: A nuclear density gauge used for compaction testing must be operated under which federal agency's regulations?
- EPA
- OSHA
- NRC (Nuclear Regulatory Commission) (Correct answer)
- DOT
Correct answer: NRC (Nuclear Regulatory Commission)
Nuclear gauges contain radioactive sources regulated by the NRC, requiring proper licensing and safety protocols.
Question 3: What does the term 'percent compaction' mean when field testing embankment materials?
- The ratio of field dry density to maximum lab dry density times 100 (Correct answer)
- The ratio of wet density to dry density
- The difference between maximum and minimum density
- The moisture content at optimum compaction
Correct answer: The ratio of field dry density to maximum lab dry density times 100
Percent compaction is the field dry density divided by the maximum dry density from lab proctor testing, expressed as a percentage.
Question 4: Which reinforcing steel test verifies that the bar will bend without cracking?
- Tensile strength test
- Bend test (Correct answer)
- Charpy impact test
- Rockwell hardness test
Correct answer: Bend test
The bend test per ASTM A615 confirms reinforcing steel ductility by bending the bar around a pin without fracture.
Question 5: When performing a sieve analysis, what property of aggregate does the gradation curve represent?
- Shape and angularity
- Particle size distribution (Correct answer)
- Specific gravity
- Absorption capacity
Correct answer: Particle size distribution
A sieve analysis produces a gradation curve showing the distribution of aggregate particle sizes by percentage passing each sieve.
Question 6: What is the primary purpose of a California Bearing Ratio (CBR) test for subgrade soils?
- Measure in-place density
- Evaluate load-bearing capacity for pavement design (Correct answer)
- Determine permeability
- Assess frost susceptibility
Correct answer: Evaluate load-bearing capacity for pavement design
The CBR test provides a measure of soil strength used directly in flexible pavement design to size base and subbase layers.
Question 7: Which defect in structural steel welding appears as a crack running along the center of a weld bead?
- Porosity
- Undercut
- Centerline (longitudinal) crack (Correct answer)
- Incomplete fusion
Correct answer: Centerline (longitudinal) crack
Centerline or longitudinal weld cracks run along the weld axis and are often caused by high restraint or improper filler metal selection.
CPII Materials & Testing 3
Which test method is used to determine the air content of freshly mixed concrete by the pressure method?