Asphalt Definitions and Terminology
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Learn about asphalt with our list of asphalt definitions and terms below. You can also download a pdf copy of this asphalt definitions resource.
Absolute Viscosity
Absolute viscosity is a method of measuring viscosity using poise as the primary measurement unit. This method utilizes a partial...
Aggregate
Aggregate is a hard inert granular material of mineral composition such as sand, gravel, slag, or crushed stone, used in...
Air Voids
Empty spaces (air pockets) in a compacted mix surrounded by asphalt coated particles, expressed as a percentage by volume of...
Alligator Cracks
Alligator cracks are interconnected cracks forming a series of small blocks resembling an alligator’s skin or chicken wire caused by...
Asphalt
A dark brown to black cementitious material in which the predominating constituents are bitumens that occur in nature or are...
Asphalt Binder
A term utilized in the Superpave Mix Design System to classify the grade of asphalt cement used in an asphalt...
Asphalt Cements
A fluxed or unfluxed asphalt specially prepared for quality and consistency for direct use in the manufacture of asphalt pavements.
Asphalt Leveling Course
A course of hot mix asphalt (usually a relatively fine-graded asphalt aggregate mixture) of variable thickness is used to eliminate...
Asphalt Rubber
Asphalt Rubber or AR for short, is used to modify liquid asphalt to increase performance and durability.
Automatic Dryer Control
A system that automatically maintains the temperature of aggregates discharged from the dryer within a preset range.
Automatic Proportioning Control
A system in which proportions of the aggregate and asphalt fractions are controlled using gates or valves, which are opened...
Balanced Mix Design
Balanced Mix Design or BMD is an asphalt mix design using performance tests on specimens that address multiple modes of...
Base Course
Base course is the material layer immediately beneath the surface or intermediate course. It may be composed of crushed stone,...
Batch Plant
A batch plant is a manufacturing facility for producing asphalt paving mixtures. A batch plant distributes the aggregate constituents proportionately...
Bending Beam Rheometer
Bending Beam Rheometer, also known as BBR, measures the low-temperature stiffness and relaxation properties of asphalt binders, indicating an asphalt...
Bitumen
Bitumen is a black or dark-colored (solid, semisolid, or viscous) cementitious substance, natural or manufactured, composed principally of high molecular...
Bleeding or Flushing
Bleeding or flushing is the upward movement of asphalt in an asphalt pavement resulting in the formation of a film...
Bulk Specific Gravity Gsb
Bulk Specific Gravity, or Gsb, is the ratio of the mass in air of a unit volume of a permeable...
Coal Tar
Coal tar is a dark brown to black cementitious material produced by the destructive distillation of bituminous coal.
Coarse-Graded Aggregate
A continuous grading characterizes coarse-graded aggregate in sizes of particles from coarse through fine with a predominance of coarse sizes.
Cold Feed Bins
Cold feed bins are bins that store the necessary aggregate sizes and feed them to the dryer drum of the...
Cold Mix
Cold mix or cold patch is a mixture of emulsified asphalt and aggregate; produced in a central plant (plant mix)...
Compaction
Compaction is compressing a given volume of material into a smaller volume. Insufficient compaction of the asphalt pavement courses may...
Consensus Properties
Consensus properties are aggregate characteristics critical to well-performing hot mix asphalt, regardless of the aggregate source, and whose limiting values...
Consistency
Consistency describes the degree of fluidity or plasticity of asphalt binder at any particular temperature. The consistency of asphalt binder...
Continuous Mix Plant
A continuous mix plant is a manufacturing facility for producing asphalt paving mixtures by portioning those aggregate and asphalt constituents...
Corrugations
Corrugations (wash boarding and shoving) are a type of pavement distortion. Corrugation is a plastic movement typified by ripples across...
Cracks
Cracks are breaks in the surface of an asphalt pavement. The common types are: Alligator Cracks Edge Joint Cracks Longitudinal...
Cutback Asphalt
Cutback asphalt is an asphalt cement that has been liquefied by blending with a petroleum solvent (also called a diluent)....
Dense-Graded Aggregate
Dense-graded aggregate has a particle size distribution such that when it is compacted, the resulting voids between the aggregate particles,...
Density
Density is the degree of solidity (compaction) achieved in a given mixture, which will be limited only by the total...
Drum Mix Plant
A drum mix plant is a manufacturing facility for producing asphalt paving mixtures that continuously proportions the aggregate constituents into...
Dryer
The dryer is the component of the asphalt plant that dries and heats the aggregates to the specified temperatures. Dryers...
Ductility
Ductility is the ability of a substance to be drawn out or stretched thin. While ductility is considered an important...
Durability
Durability is the property of an asphalt paving mixture that describes its ability to resist disintegration by weathering and traffic....
Dynamic Shear Rheometer
A dynamic shear rheometer, or DSR, measures the high-temperature rheological properties of asphalt binders. Used to predict the end-use performance...
Edge Joint Cracks
Edge joint cracks are the separation of the joint between the pavement and the shoulder, commonly caused by alternate wetting...
Effective Asphalt Content
Effective asphalt content, or Pbe, is the total asphalt content of a mix minus the portion absorbed into the aggregate...
Effective Specific Gravity
Effective specific gravity, or Gse, is the ratio of the mass in air of a unit volume of a porous...
Emulsified Asphalt
Emulsified asphalt is an emulsion of asphalt cement and water containing a small emulsifying agent, a heterogeneous system comprising two...
Fatigue Resistance
Fatigue resistance is the ability of asphalt pavement to withstand repeated flexing or slight bending caused by the passage of...
Fine-graded Aggregate
Fine-graded aggregate is one having a continuous grading in sizes of particles from coarse through fine with a predominance of...
Flexibility
Flexibility is the ability of an asphalt pavement structure's ability to conform to the foundation's settlement. Generally, the flexibility of...
Full-depth Asphalt Pavement
The term full-depth (registered by the asphalt institute with the u.s. Patent Office) certifies that the pavement is one in...
Hamburg
Hamburg is a laboratory wheel-tracking test. Used to determine mix performance regarding rutting, fatigue, moisture susceptibility, and stripping predictions.
Hot Mix Asphalt
Hot mix asphalt (asphalt concrete) is a high-quality, thoroughly controlled uniform mixture of asphalt binder and well-graded aggregate fractions, thoroughly...
Ideal Crack Test
The Ideal Crack Test, also known as Ideal CT, is a test method to determine the indirect tensile strengths of...
Impermeability
Impermeability is the resistance an asphalt pavement has to the passage of air and water into or through the pavement.
International Roughness Index
International Roughness Index, or IRI, is used worldwide as a standard to quantify road surface roughness.
Kinematic Viscosity
Kinematic viscosity is a method of measuring viscosity using the stoke as the primary measurement unit.
Longitudinal Joint Cracks
Longitudinal joint cracks are longitudinal separations along the seam between two paving lanes caused by a weak seam between adjoining...
Manual Proportioning Control
Manual proportioning control is a system that controls proportions of the aggregate and asphalt fractions using manually controlled gates or...
Maximum Specific Gravity
Maximum specific gravity, or Gmm, is the maximum specific gravity of uncompacted bituminous paving mixtures.Â
Mineral Filler
Mineral filler is a finely divided mineral product, at least 70 percent of which will pass a 0.075mm (no. 200)...
Open-graded Aggregate
Open-graded aggregate is one containing little or no mineral filler in which void spaces in the compacted aggregate are relatively...
Open-Graded Asphalt Friction Course
Open-graded asphalt friction course is a pavement surface course consisting of a high-void asphalt plant mix that permits rapid rainwater...
Overlay Test
The overlay test determines the susceptibility of bituminous mixtures to fatigue or reflective cracking. Results are values in critical fracture...
Pavement Structure
Pavement structure refers to all the courses of asphalt-aggregate mixtures or a combination of asphalt courses and untreated aggregate courses...
Penetration
Penetration is the consistency of a bituminous material expressed as the distance in tenths of a millimeter (0.1 mm) that...
Performance Graded
Performance graded (PG) is an asphalt binder grade designation used in Superpave; based on the binder's mechanical performance at critical...
Permanent Deformation
Permanent deformation is deformation that stays even after removing the applied force.
Plant Screens
Plant screens are between the dryer and hot bins in a batch, separating the heated aggregates into the proper hot...
Poise
Poise is a centimeter-gram-second unit of absolute viscosity, equal to the viscosity of a fluid which requires stress of one...
Polymer-Modified Asphalt
Polymer-modified Asphalt (PMA) is liquid asphalt modified to increase performance and durability.
Polymer-Modified Asphalt Binder
Polymer-modified asphalt binder is a conventional asphalt cement containing added styrene block copolymer or styrene butadiene rubber (SBR) latex or...
Raveling
Raveling is the progressive separation of aggregate particles in a pavement from the surface downward or from the edges inward....
Recycled Asphalt Shingles
To increase stiffness, recycled asphalt shingles (RAS) are utilized in bituminous mixtures.
Recycled Engine Oil Bottoms
Recycled engine oil bottoms, or REOBs, soften hard pen asphalt. Texas no longer utilizes REOBs.
Reflection Cracks
Reflection cracks are cracks in asphalt overlays that reflect the crack pattern in the pavement structure underneath. Vertical or horizontal...
Rutting
Rutting describes grooves that develop in the wheel tracks of a pavement. Rutting may result from consolidation or lateral movement...
Sand Asphalt
Sand asphalt is a mixture of sand and natural or manufactured asphalt cement (or, in some cases, both natural and...
Segregation
Segregation occurs in the asphalt mat. There are two types, mechanical and thermal. Both can cause poor performance of the...
Shrinkage Cracks
Shrinkage cracks are interconnected cracks forming a series of large blocks, usually with sharp corners or angles. Asphalt mix, base,...
Sieve
A sieve is an apparatus used in laboratory work with square openings for separating material sizes.
Skid Resistance
Skid resistance is the ability of an asphalt paving surface, particularly when wet, to offer resistance to slipping or skidding....
Slippage Cracks
Slippage cracks are crescent-shaped cracks that are open in the direction of the thrust of wheels on the pavement surface....
Solubility
Solubility measures the purity of an asphalt binder or the ability of the asphalt binder's soluble portion to be dissolved...
Stability
Stability is the ability of the asphalt paving mixture to resist deformation from imposed loads. Stability is dependent upon both...
Stabilized Subgrade
A stabilized subgrade is a subgrade improved to be a working platform by (1) the incorporation of granular materials or...
Stoke
Stoke refers to a unit of kinematic viscosity equal to the viscosity of a fluid in poises divided by the...
Stone Matrix Asphalt
Stone matrix asphalt (SMA) is a surface mix that utilizes liquid polymer modifiers, fibers, and mineral fillers. Many consider it...
Subbase
Subbase refers to the course in the asphalt pavement structure immediately below the base course is called the subbase course....
Superpave
Superpave (trademark) is short for "superior performing asphalt pavement," a performance-based system for selecting and specifying asphalt binders and developing...
Superpave Gyratory Compactor
A Superpave Gyratory Compactor (SGC) is used during Superpave mix design or field testing activities for compacting hot mix asphalt...
Superpave Mix Design
A Superpave mix design is a mix design system that integrates selecting materials (asphalt, aggregate) and volumetric proportioning with the...
Viscosity
Viscosity is a measure of the resistance to flow. It is one method of measuring the consistency of asphalt. See...
Voids
Voids are empty spaces (air pockets) in a compacted mix surrounded by asphalt-coated particles.
Voids Filled with Asphalt
Voids Filled with Asphalt (VFA) refers to the percentage of the voids in the mineral aggregate structure filled with asphalt,...
Voids in Mineral Aggregate
Voids in Mineral Aggregate (VMA) refers to the volume of void space (air pockets) between the aggregate particles of a...
Voids in Total Mix
Voids in Total Mix (VTM) refers to the total empty spaces (air pockets) in a compacted mix expressed as a...
Warm Mix Asphalt
Warm Mix Asphalt (WMA) is produced at a temperature between 215 degrees and 270 degrees.
Well-graded Aggregate
Well-graded aggregate is graded from the maximum size down to filler to obtain an asphalt mix with a controlled void...