PIC Paving Procedures & Equipment Operation 3 — Questions and Answers
Question 1: When constructing a longitudinal joint between two adjacent paving lanes, which practice best ensures joint density?
- Pave the second lane cold to allow hand-raking
- Overlap the second lane 2–3 inches over the first lane edge and shift the roller to confine material (Correct answer)
- Use a vibratory roller directly on the joint in the first pass
- Apply additional tack coat only to the top of the first lane edge
Correct answer: Overlap the second lane 2–3 inches over the first lane edge and shift the roller to confine material
Overlapping the adjacent lane 2–3 inches and using the roller to confine mix over the joint produces a hot, dense longitudinal joint with minimal air voids.
Question 2: What is the function of the 'angle of attack' (screed angle of incidence) on an asphalt paver?
- It determines the angle at which the truck dumps material into the hopper
- It controls the thickness and density of the mat being laid (Correct answer)
- It sets the speed of the auger distribution system
- It aligns the paver with the road centerline
Correct answer: It controls the thickness and density of the mat being laid
The screed's angle of attack (tow-point angle) controls mat thickness and influences the initial density; a slightly positive angle causes the screed to 'float' and produce a denser mat.
Question 3: During asphalt paving operations, why should a paver stop be avoided whenever possible?
- Stopping increases fuel consumption significantly
- Paver stops cause screed marks and bumps that are difficult to remove later (Correct answer)
- Stopping causes the auger to reverse direction
- Paver stops require re-calibration of the automatic grade control
Correct answer: Paver stops cause screed marks and bumps that are difficult to remove later
When a paver stops, the heated screed continues to sit on the mat, over-compacting and potentially causing a bump that produces a roughness defect in the finished pavement.
Question 4: What is the recommended overlap of the steel drum roller on each pass to ensure uniform compaction coverage?
- 1–2 inches
- 6–8 inches (Correct answer)
- 12–18 inches
- 24–30 inches
Correct answer: 6–8 inches
A 6–8 inch overlap on adjacent roller passes ensures that no strip of mat is missed and that edge areas receive adequate compaction.
Question 5: A paving crew is placing mix in cold weather (45°F air temperature). Which adjustment is most important to maintain mix workability?
- Increase roller drum water flow rate
- Reduce paving speed and haul distance, and increase mix delivery temperature (Correct answer)
- Switch to a lighter-grade binder without specification approval
- Increase screed vibration amplitude
Correct answer: Reduce paving speed and haul distance, and increase mix delivery temperature
In cold weather, reducing paving speed, shortening haul distances, and increasing plant delivery temperature are the primary strategies to keep the mix workable long enough to achieve compaction.
Question 6: What is the primary purpose of a 'wedge joint' (tapered edge) at a transverse joint?
- To improve the aesthetic appearance of the pavement edge
- To allow traffic to transition smoothly and protect the joint from raveling (Correct answer)
- To reduce the amount of material needed at the joint
- To eliminate the need for a tack coat at the joint face
Correct answer: To allow traffic to transition smoothly and protect the joint from raveling
A tapered or wedge joint provides a smooth traffic transition while protecting the vertical face of the joint from traffic-induced edge stress that promotes raveling and deterioration.
Question 7: Which instrument is most commonly used by a paving inspector to measure the surface temperature of a freshly placed HMA mat?
- Thermocouple probe inserted into the mix
- Infrared thermometer (pyrometer) (Correct answer)
- Liquid-in-glass thermometer
- Bimetallic dial thermometer
Correct answer: Infrared thermometer (pyrometer)
An infrared thermometer allows a paving inspector to quickly and non-destructively measure mat surface temperature across a wide area without disturbing the fresh asphalt.
PIC Paving Procedures & Equipment Operation 3
When constructing a longitudinal joint between two adjacent paving lanes, which practice best ensures joint density?