PIC Pavement Joints & Longitudinal Seam Construction 1 — Questions and Answers
Question 1: When placing HMA adjacent to a cold longitudinal joint, what is the recommended overlap of the new mat over the cold edge before rolling begins?
- Less than 0.25 in (6 mm)
- 1 to 3 in (25 to 75 mm) (Correct answer)
- 4 to 6 in (100 to 150 mm)
- 6 to 8 in (150 to 200 mm)
Correct answer: 1 to 3 in (25 to 75 mm)
A 1 to 3 inch overlap allows the roller to press the hot mix back flush with the joint line, sealing the seam and improving density at the edge.
Question 2: A longitudinal 'cold' joint is formed when:
- Paving is performed during nighttime in cool ambient temperatures
- The previously placed lane has cooled beyond its compaction temperature range before the adjacent lane is placed (Correct answer)
- A joint sealant has been applied to the pavement edge
- Two lifts are placed within the same work shift
Correct answer: The previously placed lane has cooled beyond its compaction temperature range before the adjacent lane is placed
Once the existing lane cools below the minimum rolling temperature, it can no longer be compacted together with the new lane, classifying it as a cold joint requiring special preparation.
Question 3: Which paving method best eliminates cold longitudinal joints on multi-lane projects?
- Tandem breakdown rolling pass
- Echelon (abreast) paving with two or more pavers (Correct answer)
- Wedge-and-level course paving
- Cold butt-joint construction with saw cut
Correct answer: Echelon (abreast) paving with two or more pavers
In echelon paving, adjacent lanes are placed simultaneously so both mats remain hot at the joint, allowing them to be compacted together for improved density and bond.
Question 4: During breakdown rolling at a longitudinal cold joint, the roller drum should be positioned with approximately how much of its width on the cold previously compacted lane?
- 100% of the drum width on the cold lane
- 50% on the cold lane and 50% on the hot lane
- Approximately 6 inches (150 mm) on the cold lane, with the remainder on the hot lane (Correct answer)
- No drum contact on the cold lane at all
Correct answer: Approximately 6 inches (150 mm) on the cold lane, with the remainder on the hot lane
Placing about 6 inches of the drum on the cold lane and the rest on the hot lane compacts the new material toward the joint without displacing the set pavement.
Question 5: Why is it undesirable to place longitudinal joints beneath vehicle wheel paths?
- It makes density testing more difficult
- Repeated wheel loading accelerates joint cracking and water infiltration at the seam (Correct answer)
- Compaction equipment cannot safely operate in wheel paths
- Joint sealant fails to adhere in high-traffic areas
Correct answer: Repeated wheel loading accelerates joint cracking and water infiltration at the seam
Wheel paths subject joints to high cyclic stresses and water infiltration, which accelerate raveling and longitudinal cracking at the seam over time.
Question 6: Before placing a new lane against a cold longitudinal joint face, what should the inspector verify has been applied to the vertical face?
- Portland cement slurry to fill voids in the face
- Tack coat of emulsified asphalt to the vertical joint face (Correct answer)
- Prime coat of MC cutback asphalt
- Fog seal sprayed over the exposed joint area
Correct answer: Tack coat of emulsified asphalt to the vertical joint face
Tack coat applied to the vertical cold joint face promotes adhesion between the new hot-mix and the cured asphalt lane, improving bond and reducing water infiltration.
Question 7: An inspector observes that a longitudinal joint is consistently raised 0.5 inches above the adjacent lane after compaction. This condition is most likely caused by:
- Excessive roller speed during joint compaction passes
- Insufficient tack coat applied to the joint face
- Too much HMA overlap maintained during paving across the cold joint (Correct answer)
- The adjacent cold lane was placed at an excessively high temperature
Correct answer: Too much HMA overlap maintained during paving across the cold joint
Excessive overlap of the new lane over the cold joint results in a high ridge after rolling because the surplus material has insufficient space to compact flush.
PIC Pavement Joints & Longitudinal Seam Construction 1
When placing HMA adjacent to a cold longitudinal joint, what is the recommended overlap of the new mat over the cold edge before rolling begins?