NICET CMT Asphalt flashcards
NICET CMT Asphalt · Build recall with a focused review session.
33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- PG binder grade meaning
- Performance Grade notation gives the average 7-day maximum pavement temperature and the minimum pavement temperature in degrees Celsius that the binder must withstand without rutting or low-temperature cracking.
- Gmm definition
- Maximum theoretical specific gravity of an asphalt mixture with no air voids; it is the reference density for computing percent compaction and air void content in both laboratory and field specimens.
- Gsb definition
- Bulk specific gravity of the combined aggregate, based on the total volume including permeable pores; used to compute VMA and absorbed binder content in volumetric analysis.
- Gse definition
- Effective specific gravity of the aggregate, excluding pores that absorb asphalt binder; it is back-calculated from the measured Gmm of the mixture and the binder content.
- VMA definition
- Voids in mineral aggregate: the intergranular void space between aggregate particles, expressed as a percentage of bulk volume, that contains both air voids and effective asphalt binder.
- VFA definition
- Voids filled with asphalt: the percentage of the VMA that is occupied by effective asphalt binder, calculated as 100 times air void content divided by VMA.
- Dust-to-binder ratio
- Ratio of percent passing the 0.075 mm sieve to effective asphalt binder content; typical Superpave specification range is 0.6 to 1.2 by mass.
- Ndesign gyrations
- Number of gyrations in the Superpave gyratory compactor used to compact specimens to the design air void content of 4 percent; varies with traffic level and depth.
- TSR test purpose
- Tensile strength ratio from AASHTO T 283 compares wet and dry indirect tensile strengths to assess moisture susceptibility; values at or above 0.80 generally pass.
- Percent compaction formula
- Field density expressed as a percentage of the laboratory maximum theoretical specific gravity Gmm; typical dense-graded acceptance targets are 92 to 93 percent of Gmm.
- Marshall stability
- Peak load in newtons that a compacted specimen resists at 60 degrees Celsius when loaded diametrically; flow is the deformation at peak load.
- Asphalt binder content Pb
- Total binder mass expressed as a percentage of total mixture mass; it is reduced by absorbed binder to give the effective binder content used in volumetric calculations.
- Absorbed binder Pba
- Binder that penetrates permeable aggregate pores and does not contribute to coating or film thickness; computed from Gse, Gsb, and binder specific gravity.
- Air voids Va
- Percentage of the compacted mixture volume occupied by air; calculated as 100 times (Gmm minus Gmb) divided by Gmm.
- Gmb definition
- Bulk specific gravity of a compacted asphalt specimen, determined by saturated surface-dry mass and submerged mass; used to compute air voids and percent compaction.
- Reclaimed asphalt pavement
- Milled or processed asphalt material reused in new mixtures; its aged binder is accounted for in the total binder grade and content through blending assumptions.
- PG 64-22 use case
- Binder grade suited to climates with hot pavement temperatures near 64 degrees Celsius and cold pavement temperatures no colder than minus 22 degrees Celsius.
- Superpave mix design steps
- Select aggregate structure, determine binder content at 4 percent air voids, then evaluate moisture sensitivity and rutting resistance before finalizing the job mix formula.
- Theoretical maximum density
- Another name for Gmm-based density; it represents the mass per unit volume of a voidless mixture and is the denominator in percent compaction calculations.
- Bulk specific gravity T 166
- AASHTO test method for bulk specific gravity of compacted asphalt specimens using saturated surface-dry and submerged masses; requires careful surface drying.
- Gyratory compactor purpose
- Laboratory device that compacts asphalt specimens by combined vertical pressure and gyration, producing density comparable to field rolling for volumetric design.
- Film thickness concept
- Effective binder volume divided by aggregate surface area; it influences durability, and mixes with high dust content or low binder may have inadequate film thickness.
- Job mix formula
- Approved document specifying aggregate gradation, binder grade and content, and volumetric targets that the producer must meet during plant production.
- Gradation 0.45 chart
- Plot of percent passing against sieve size raised to the 0.45 power; a straight line indicates a dense, well-graded aggregate structure in Superpave design.
- Nominal maximum aggregate size
- One sieve size larger than the first sieve that retains more than 10 percent of the aggregate; it governs lift thickness and sample size requirements.
- Moisture susceptibility
- Tendency of an asphalt mixture to lose strength when saturated; evaluated by AASHTO T 283 and mitigated with antistrip additives such as hydrated lime.
- Binder specific gravity Gb
- Specific gravity of the asphalt binder, typically near 1.02 to 1.04; it is used in absorbed binder and effective binder content calculations.
- Effective binder content Pbe
- Total binder content minus the absorbed portion, expressed as a percentage of aggregate mass; it forms the asphalt film around aggregate particles.
- Rutting resistance evaluation
- Superpave evaluates rutting potential using gyratory compaction curves and, for high-traffic mixes, performance tests such as the asphalt pavement analyzer or flow number.
- Saturated surface-dry mass
- Mass of a compacted specimen with surface moisture removed but permeable pores still filled; used with submerged mass to compute bulk specific gravity.
- Lift thickness rule
- Compacted lift thickness should generally be at least three to four times the nominal maximum aggregate size to allow proper compaction and avoid aggregate bridging.
- Sampling for acceptance
- Field samples for density and volumetric verification must be random and representative; locations are typically selected by a random number procedure before coring.
- Antistrip additive
- Chemical or mineral additive, such as hydrated lime or amine, added to improve binder-aggregate bonding and raise the tensile strength ratio in moisture tests.