NETTCP Asphalt Technology 3 — Questions and Answers
Question 1: What is the typical compaction temperature range for a conventional HMA mix using PG 64-22 binder?
- 100–120°F (38–49°C)
- 175–200°F (79–93°C)
- 270–310°F (132–154°C) (Correct answer)
- 375–400°F (191–204°C)
Correct answer: 270–310°F (132–154°C)
HMA compaction typically occurs between 270–310°F to achieve proper density before the mix cools and stiffens.
Question 2: What does 'bleeding' (flushing) indicate about an asphalt pavement surface?
- Insufficient asphalt binder content
- Excess asphalt binder migrating to the surface (Correct answer)
- High air void content causing raveling
- Reflective cracking from underlying layers
Correct answer: Excess asphalt binder migrating to the surface
Bleeding occurs when excess binder fills air voids and rises to the pavement surface, creating a shiny, slick film.
Question 3: Which quality control test is performed in the field to estimate the asphalt content of a mix during paving?
- Marshall stability test
- Nuclear or non-nuclear density gauge reading
- Ignition oven extraction test (Correct answer)
- Hveem stabilometer test
Correct answer: Ignition oven extraction test
The ignition oven burns off the binder from a mix sample, allowing technicians to calculate asphalt content by weight difference.
Question 4: What aggregate characteristic is measured by the Los Angeles abrasion test?
- Aggregate shape and angularity
- Resistance to degradation under impact and abrasion (Correct answer)
- Specific gravity and absorption
- Flat and elongated particle percentage
Correct answer: Resistance to degradation under impact and abrasion
The LA abrasion test measures aggregate toughness by tumbling samples with steel charges and measuring the percentage of material worn away.
Question 5: In warm-mix asphalt (WMA) technology, what is the primary benefit of reducing production temperatures?
- Eliminating the need for compaction
- Reducing fuel consumption and worker fume exposure (Correct answer)
- Increasing the asphalt binder content
- Eliminating the need for tack coats
Correct answer: Reducing fuel consumption and worker fume exposure
WMA produced at 30–100°F lower temperatures cuts fuel use, reduces emissions, and lowers worker exposure to asphalt fumes.
Question 6: What is the standard method for determining the theoretical maximum specific gravity (Gmm) of an asphalt mix?
- Marshall stability test
- AASHTO T 209 (Rice test) (Correct answer)
- Hveem compaction method
- AASHTO T 308 ignition method
Correct answer: AASHTO T 209 (Rice test)
AASHTO T 209 (the Rice test) measures Gmm by determining the density of a loose asphalt mix with all air voids removed under vacuum.
Question 7: Which pavement layer is directly beneath the surface course and provides structural support and load distribution?
- Subgrade
- Subbase
- Binder (intermediate) course (Correct answer)
- Wearing course
Correct answer: Binder (intermediate) course
The binder course sits between the surface wearing course and the base, distributing traffic loads and providing structural capacity.
NETTCP Asphalt Technology 3
What is the typical compaction temperature range for a conventional HMA mix using PG 64-22 binder?