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ASPHALTIC TERMINOLOGY
This IM describes the terminology associated with asphaltic materials.
Asphalt Cement See Binder
Binder A dark brown to black cementitious material, which occurs in nature or is obtained in petroleum processing. Also commonly referred to Asphalt Cement (AC).
Bitumen See Binder
Cutback Asphalt Liquid asphalt composed of asphalt binder and a petroleum solvent. Cutback asphalts have three types (Rapid Curing (RC), Medium Curing (MC), and Slow Curing (SC)). The petroleum solvent, also called diluents, can have high volatility (RC) to low volatility (SC).
Emulsified Asphalt Composed of asphalt binder and water, and a small quantity of emulsifying agent, which is similar to detergent. They may be of either the Anionic, electro-negatively-charged asphalt globules, or Cationic, electro-positively-charged asphalt globules types, depending upon the emulsifying agent. Emulsified asphalt is produced in three grades (Rapid-Setting (RS), Medium-Setting (MS), and Slow-Setting (SS)).
Flux or Flux Oil A thick, relatively nonvolatile fraction of petroleum, which may be used to soften asphalt binder to a desired consistency.
Foamed Asphalt A combination of high temperature asphalt binder and water to produce foaming.
Gilsonite A form of natural asphalt, hard and brittle, which is mined.
Modified Binder These are asphalt binders, which have been physically- and/or chemically-altered (usually with an additive) to bring the characteristics of the binder to what is desired for the application. This process includes polymer modification.
Performance Graded Asphalt (PG) The identification associated with the grading of the binder. Prior identification methods have been penetration and viscosity grading. For example, a PG 64-22 would indicate a performance-graded binder with a high temperature confidence of 64ฐC and a low temperature confidence of -22ฐC.
Viscosity The property of a fluid or semifluid that enables it to resist flow. The higher the viscosity, the greater the resistance to flow.
AGGREGATE TERMINOLOGY
Absorption The property of an aggregate particle to take in and hold a fluid. For our purposes usually asphalt binder or water.
Aggregate Any hard, inert, mineral material used for mixing in graduated fragments. It includes sand, gravel, crushed stone, and slag.
Coarse Aggregate The aggregate particles retained on the #4 (4.75 mm) sieve.
Coarse-Graded Aggregate A blend of aggregate particles having a continuous grading in sizes of particles from coarse through fine with a predominance of coarse sizes. A gradation below the maximum density line.
Cold-Feed Gradation The aggregate proportioning system employing calibrated bins to deliver aggregate to the dryer (see IM 508 for additional information).
Fine Aggregate Aggregate particles passing the #4 (4.75 mm) sieve.
Fine-Graded Aggregate A blend of aggregate particles having a continuous grading in sizes of particles from coarse through fine with a predominance of fine sizes. A gradation above the maximum density line.
Gradation The description given to the proportions of aggregate on a series of sieves. Usually defined in terms of the % passing successive sieve sizes.
Lime A product used to enhance the bond between aggregate and asphalt binder. It is composed of dust from crushed limestone. Hydrated lime is often specified for surface mixes.
Manufactured Sand The predominately minus #4 (4.75 mm) material produced from crushing ledge rock or gravel.
Mineral Filler A finely divided mineral product at least 70 percent of which will pass a #200 (75 μm) sieve. Pulverized limestone is the most commonly manufactured filler, although other stone dust, hydrated lime, Portland cement, fly ash and certain natural deposits of finely divided mineral matter are also used.
Natural Sand A loose, granular material found in natural deposits.
Open-Graded Aggregate A blend of aggregate particles containing little or no fine aggregate and mineral filler and the void spaces in the compacted aggregate are relatively large.
Slag A byproduct of steel production.
Well-Graded Aggregate Aggregate that is uniformly graded from coarse to fine.
Asphalt Cement Concrete See Hot Mix Asphalt
Asphalt Leveling Course Lift(s) of HMA of variable thickness used to eliminate irregularities in the contour of an existing surface prior to overlay.
Asphalt Overlay One or more lifts of HMA constructed on an existing pavement. The overlay may include a leveling course to correct the contour of the old pavement, followed by uniform course or courses to provide needed thickness.
Base Course Lift(s) of HMA pavement placed on the subgrade or subbase on which successive layers are placed.
Binder Course See Intermediate Course
Full-Depthฎ Asphalt Pavement The term Full-Depthฎ certifies that the pavement is one in which asphalt mixtures are employed for all courses above the subgrade or improved subgrade. A Full-Depthฎ asphalt pavement is laid directly on the prepared subgrade.
Hot Mix Asphalt (HMA) Asphalt binder/aggregate mixture produced at a batch or drum-mixing facility that must be spread and compacted while at an elevated temperature. To dry the aggregate and obtain sufficient fluidity of the binder, both must be heated prior to mixing giving origin to the term hot mix.
Intermediate Course An HMA pavement course between a base course and a surface course.
Job Mix Formula (JMF) The JMF is the mix design used to begin a HMA project. It is also used as the basis for the control of plant produced mixture. It sets the proportions of the aggregate and amount of asphalt binder.
Mixed-In-Place (Road Mix) An HMA course produced by mixing mineral aggregate and cutback or emulsified asphalt at the road site by means of travel plants, motor graders, or special road-mixing equipment.
Plant Mix A mixture, produced in an asphalt mixing facility that consists of mineral aggregate uniformly coated with asphalt binder, emulsified asphalt or cutback asphalt.
Sand Asphalt A mixture of sand and asphalt binder, cutback or emulsified asphalt. It may be prepared with or without special control of aggregate grading and may or may not contain mineral filler. Either mixed-in-place or plant-mix construction may be employed.
Sheet Asphalt A hot mixture of binder with clean angular, graded sand and mineral filler.
Surface Course The top lift(s) of HMA pavement, sometimes called asphalt wearing course.
Warm-Mix Asphalt (WMA) Similar to HMA but produced by using additives that allow the mix to be produced, placed and compacted at lower temperatures.
Asphalt Joint Sealer An asphalt product used for sealing cracks and joints in pavements and other structures.
Average Absolute Deviation (AAD) The absolute value of the difference of a test result from a specified value, averaged for a specified set of values.
Cold-In-Place Recycling A method of rehabilitating the HMA surface by milling, adding a stabilizing agent, relaying and compacting in a continuous operation (see IM 504 for additional information).
Durability The property of an asphalt paving mixture that describes its ability to resist the detrimental effects of air, water and temperature. Included under weathering are changes in the characteristics of asphalt, such as oxidation and volatilization, and changes in the pavement and aggregate due to the action of water, including freezing and thawing.
Fatigue Resistance The ability of asphalt pavement to withstand repeated flexing caused by the passage of wheel loads.
Field Density The density (Gmb (field)) of HMA based on field roller compaction.
Field Voids The percent by volume of air voids in cores cut from the finished pavement.
Flexibility The ability of an asphalt paving mixture to be able to bend slightly, without cracking, and to conform to gradual settlements and movements of the base and subgrade.
Fog Seal A light application of emulsion diluted with water that is applied without mineral aggregate cover.
Lab Density The density (Gmb (lab)) of HMA based on laboratory compaction.
Lab Voids The percent by volume of air voids in laboratory compacted specimens.
Pay Factor A calculated multiplier used to determine adjustments to payment to the contractor. Pay factors greater than 1.000 are referred to as incentive and pay factors less than 1.000 are referred to as disincentive or penalties
Percent Within Limits (PWL) A statistical estimation of the percentage of a material that falls between specified limits based on sampling and testing of the material. PWL is used to calculate the pay factor.
Permeability The resistance that an asphalt pavement has to the passage of air and water into or through the pavement.
Recycled Asphalt Pavement (RAP) HMA removed and processed, generally by milling. This material may be stored and used in mixtures in addition to virgin aggregate and binder. This is also referred to as Reclaimed Asphalt Pavement.
Recycled Asphalt Shingles (RAS) Roofing shingles, either waste from a shingle manufacturer or tear off shingles from reroofing operations. Shingles contain a high percentage of asphalt as well as fibers and fine aggregate. Shingles are processed into a fine material and handled similar to RAP.
Seal Coat A thin asphalt surface treatment used to waterproof and improve the texture of an asphalt wearing surface. Depending on the purpose, seal coats may or may not be covered with aggregate. The main types of seal coats are aggregate seals, fog seals, emulsion slurry seals and sand seals.
Skid Resistance The ability of asphalt paving surface, particularly when wet, to offer friction against the tire surface.
Slurry Seal A mixture of emulsified asphalt, fine aggregate and mineral filler, with water added to produce flowing consistency.
Stability The ability of asphalt paving mixtures to resist deformation from imposed loads. Unstable pavements are marked by channeling (ruts), and corrugations (washboarding).
Surface Treatments A broad term embracing several types of asphalt or asphalt-aggregate applications, usually less than 1 in. (25 mm) thick, to a road surface. The types range from a light application of emulsified or cutback asphalt (Fog seal) to a single or multiple surface layers made up of alternating applications of asphalt and aggregate (chip seal).
Tack Coat A very light application of asphalt, usually asphalt emulsion diluted with water. It is used to ensure a bond between the existing pavement surface and the overlay.
Batch Plant This type of HMA production plant is used to produce individual batches of mix by making use of a pugmill (see IM 508 for additional information).
Certified Plant Inspection (CPI) A specified method of quality control using a Certified Plant Inspector (see Section 2521 of the Standard Specification for additional information).
Cold-Feed The device used to combine the various aggregates, in the correct proportions.
Drum Plant This type of HMA production plant is a continuously operating plant, which mixes the aggregate, asphalt binder and RAP (if used) in the drum (See IM 508 for additional information).
Quality Management of Asphalt (QMA) A specified quality control procedure where the contractor is responsible for the mix design and the control of the mix properties during production (see IM 511 for additional information). The agency is responsible for quality assurance and verification.
Workability The ease with which paving mixtures may be placed and compacted.