CCIL CCIL - Canadian Council of Independent Laboratories Pavement Construction and Inspection Questions and Answers 2 — Questions and Answers
Question 1: What is the primary purpose of tack coat applied between asphalt pavement layers?
- To bond successive asphalt lifts together to prevent slippage (Correct answer)
- To waterproof the surface before placing the next lift
- To reduce segregation at the screed of the paving machine
- To cool the underlying lift before the overlay is placed
Correct answer: To bond successive asphalt lifts together to prevent slippage
Tack coat (typically SS-1h or CSS-1h emulsion) creates an adhesive bond between existing and new asphalt layers, preventing horizontal slippage under traffic loads.
Question 2: What AASHTO standard test method governs measuring ride quality of pavement using a profilograph or inertial profiler?
- AASHTO R 57 / ASTM E950 (Correct answer)
- AASHTO T 246
- AASHTO T 168
- AASHTO M 320
Correct answer: AASHTO R 57 / ASTM E950
AASHTO R 57 (referencing ASTM E950 for Class 1 profilers) covers the standard practice for operation of inertial profilers to measure longitudinal pavement profile and IRI.
Question 3: What is the purpose of conducting a field core extraction from a compacted asphalt pavement after placement?
- To verify in-place density, thickness, and extract samples for air void and VMA determination (Correct answer)
- To measure the pavement temperature gradient through the lift thickness
- To obtain specimens for resilient modulus testing in the field
- To confirm aggregate gradation after compaction has altered particle sizes
Correct answer: To verify in-place density, thickness, and extract samples for air void and VMA determination
Field cores are extracted to verify compacted density and lift thickness compliance, and laboratory analysis of cores determines air voids and voids in the mineral aggregate (VMA).
Question 4: During granular base compaction inspection, what test is commonly used to verify in-place density of crushed stone base materials?
- Sand cone test (ASTM D1556) (Correct answer)
- Standard Proctor test (ASTM D698)
- Plate load test (ASTM D1194)
- Unconfined compression test (ASTM D2166)
Correct answer: Sand cone test (ASTM D1556)
The sand cone method (ASTM D1556) measures the in-place density of granular materials by filling an excavated hole with calibrated Ottawa sand to determine the volume of material removed.
Question 5: What does the term 'mat temperature uniformity' refer to during asphalt paving inspection?
- Consistent surface temperature across the full width of the freshly placed mat behind the paver screed (Correct answer)
- Uniform temperature of the asphalt mix in the truck prior to discharge
- Equal temperature at the top and bottom of the compacted asphalt lift
- Thermal consistency of the pavement during the curing period
Correct answer: Consistent surface temperature across the full width of the freshly placed mat behind the paver screed
Mat temperature uniformity refers to avoiding cold streaks or thermal segregation across the mat width, which causes differential compaction and premature cracking.
Question 6: What is the primary indicator of rutting susceptibility in a dense-graded hot mix asphalt mix design?
- High binder content with insufficient VMA relative to aggregate structure (Correct answer)
- Low aggregate angularity and flat elongated particle content
- Excessive fines passing the No. 200 sieve above specification limits
- Low compaction temperature causing inadequate density during rolling
Correct answer: High binder content with insufficient VMA relative to aggregate structure
Rutting is most often caused by excess asphalt binder filling void space in the aggregate skeleton, reducing the load-carrying capacity through shear deformation of the binder.
CCIL CCIL - Canadian Council of Independent Laboratories Pavement Construction and Inspection Questions and Answers 2
What is the primary purpose of tack coat applied between asphalt pavement layers?