NETTCP Field Testing 2 — Questions and Answers
Question 1: When performing a nuclear density gauge test on a compacted asphalt layer, what safety precaution is mandatory before beginning?
- Calibrate the gauge on a standard reference block
- Notify nearby workers and establish an exclusion zone (Correct answer)
- Wet the surface to improve contact
- Remove the gauge battery before transport
Correct answer: Notify nearby workers and establish an exclusion zone
Nuclear gauges emit radiation, so workers must be notified and a safety exclusion zone established before use.
Question 2: A field technician collects a soil sample for moisture-density (Proctor) correlation and notices the sample bag has a hole. What is the correct action?
- Proceed with testing and note the condition
- Re-sample from the same location using an intact container (Correct answer)
- Add water to restore the original moisture
- Seal the hole with tape and continue
Correct answer: Re-sample from the same location using an intact container
Sample integrity is critical; a compromised container can cause moisture loss that invalidates test results, requiring re-sampling.
Question 3: During a concrete field test, the slump measured is 9 inches when the specification maximum is 5 inches. What should the technician do?
- Add superplasticizer to stiffen the mix
- Accept the load if air content is within range
- Reject the load and notify the inspector (Correct answer)
- Re-test after waiting 10 minutes
Correct answer: Reject the load and notify the inspector
A slump exceeding specification limits indicates excessive water content; the load must be rejected per AASHTO/ACI standards.
Question 4: What does a falling weight deflectometer (FWD) measure during pavement field testing?
- Surface friction coefficient
- Pavement layer deflection under a simulated load (Correct answer)
- Asphalt air void content
- Subgrade bearing capacity via cone penetration
Correct answer: Pavement layer deflection under a simulated load
The FWD drops a known weight onto the pavement and measures the resulting deflection basin to evaluate structural capacity.
Question 5: During a field sand cone density test, the technician spills some of the calibrated sand before completing the test. What is the correct response?
- Estimate the spilled volume and subtract it
- Collect the spilled sand and return it to the cone jar
- Void the test and start over with fresh calibrated sand (Correct answer)
- Continue the test using the remaining sand
Correct answer: Void the test and start over with fresh calibrated sand
Spilled sand compromises the known volume measurement, so the test must be voided and repeated with properly calibrated sand.
Question 6: At what temperature must Portland cement concrete be placed according to typical cold-weather construction requirements in New England?
- Above 35°F (2°C) at the point of placement
- Above 50°F (10°C) at the point of placement (Correct answer)
- Above 60°F (16°C) at the point of placement
- Above 40°F (4°C) with no upper limit
Correct answer: Above 50°F (10°C) at the point of placement
Most DOT specifications require concrete to be above 50°F (10°C) at placement to ensure proper hydration and strength gain.
Question 7: Which AASHTO test method is used to determine the air content of freshly mixed concrete using the pressure method?
- AASHTO T 119
- AASHTO T 152 (Correct answer)
- AASHTO T 166
- AASHTO T 209
Correct answer: AASHTO T 152
AASHTO T 152 (equivalent to ASTM C231) covers the pressure meter method for measuring air content in fresh concrete.
NETTCP Field Testing 2
When performing a nuclear density gauge test on a compacted asphalt layer, what safety precaution is mandatory before beginning?