Glossary

The difference between a binder's BBR stiffness-critical and m-value-critical low temperatures. More negative values indicate poorer stress relaxation.

American Association of State Highway and Transportation Officials

(also called “dynamic viscosity”) A measure of the viscosity of asphalt with respect to time, measured in poises, conducted at 60°C (140°F).

Used to treat localized distresses; partial-depth patches address surface distresses and full-depth patches address structural distresses.

Sampling, testing, and the assessment of test results to determine whether or not the quality of produced material or construction is acceptable in terms of the specifications.

American Concrete Institute. A nonprofit scientific and educational society, organized in 1904, to represent the user interest in the concrete field.

American Concrete Pavement Association. A national association representing concrete pavement contractors, cement companies, equipment and material manufacturers and suppliers.

The ingredients in PCC other than aggregate, portland cement and water. Typically, an admixture is added to alter a specific PCC property such as workability, setting time, strength or durability.

Costs of an agency activity that are directly related to the quantity of work (e.g., labor, material, equipment usage, contract pay items).

Granular material, such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast furnace slag, used with a hydraulic cementing medium to produce either concrete or mortar.

Combining multiple aggregate sources to produce a desired set of properties. Usually aggregate blending is done to improve or change gradation.

The distribution of particles of granular material among various sizes, usually expressed in terms of cumulative percentages larger or smaller than each of a series of sizes (sieve openings) or the percentages between certain ranges of sizes (sieve openings).

The mechanical locking which forms between the fractured surfaces along the crack below the joint saw cut (from the American Concrete Pavement Association).

The process of providing gentle motion in mixed concrete just sufficient to prevent segregation or loss of plasticity.

ASR is caused by chemical reaction between alkalis and certain reactive silica minerals which form a gel. The gel absorbs water, causing expansion which may damage the concrete and adjacent structures.

The expansive reaction that takes place in PCC between alkali (contained in the cement paste) and elements within an aggregate. The most common is an alkali-silica reaction. This reaction, which occurs to some extent in most PCC, can result in map or pattern cracking, surface popouts and spalling.

Alligator or fatigue cracking is a series of interconnecting cracks caused by fatigue failure of the asphalt concrete surface under repeated traffic loading.

The time-frame (usually in years) over which an analysis (e.g. LCCA, LCA) is performed.

Total volume of vehicle traffic of a highway or road for a year divided by 365 days.

Asphalt Pavement Alliance. A coalition of the Asphalt Institute, the National Asphalt Pavement Association, and the State Asphalt Pavement Associations.

The American Petroleum Institute (API) classifies crude oils by their API gravity. API gravity is an arbitrary expression of a material’s density at 15.5°C (60°F).

Acceptable Quality Level. The minimum level of actual quality at which the material or construction can be considered fully acceptable.

Represents the normalized area of a vertical slice taken through a deflection basin between the center of the test load and 914 mm (3 feet) away from the test load. Has length dimensions. (AREA Value)

A dark brown to black cementitious material in which the predominating constituents are bitumens, which occur in nature or are obtained in petroleum processing.

The principal asphaltic binding agent in HMA. "Asphalt binder" includes asphalt cement as well as any material added to modify the original asphalt cement properties.

A fluxed or unfluxed asphalt specially prepared as to quality and consistency for direct use in the manufacture of bituminous pavements, and having a penetration at 25° C (77° F) of between 5 and 300, under a load of 100 g applied for 5 s.

A mixture of asphalt binder and aggregate thoroughly mixed and compacted into a mass.

An emulsion of asphalt binder and water that contains a small amount of an emulsifying agent. Emulsified asphalt droplets may be of either the anionic (negative charge), cationic (positive charge) or nonionic (neutral).

A U.S.-based association of international petroleum asphalt/bitumen producers, manufacturers, and affiliated business.

Used to treat localized distresses; partial-depth patches address surface distresses and full-depth patches address structural distresses.

The high molecular weight hydrocarbon fraction precipitated from asphalt by a designated paraffinic naphtha solvent at a specified solvent-asphalt ratio.

The water contents that mark a fine-grained soil's changes between solid, plastic and liquid states: the shrinkage, plastic and liquid limits.

A mechanistic evaluation of pavement surface deflection basins generated by various pavement deflection devices.

The layer of material immediately beneath the pavement surface or binder course.

A layer of specified select material of planned thickness constructed on the subgrade or subbase below a pavement to serve one or more functions such as distributing loads, providing drainage, minimizing frost action, or facilitating pavement construction.

A manufacturing facility for producing HMA or PCC that makes the product in batches rather than continuously.

A class of black or dark-colored (solid, semi-solid or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, of which asphalts, tars, pitches, and asphaltenes are typical.

A mixture of asphalt binder and aggregate thoroughly mixed and compacted into a mass.

An emulsion of asphalt binder and water that contains a small amount of an emulsifying agent. Emulsified asphalt droplets may be of either the anionic (negative charge), cationic (positive charge) or nonionic (neutral).

Bleeding is a film of bituminous material on the pavement surface that creates a shiny, glasslike, reflecting surface that usually becomes quite sticky.

Block cracks are interconnected cracks that divide the pavement into approximately rectangular pieces. The blocks may range in size from approximately 0.3 by 0.3 m (1 by 1 ft.) to 3 by 3 m (10 by 10 ft.).

Blowups or buckles occur in hot weather, usually at a transverse crack or joint that is not wide enough to permit slab expansion. The insufficient width usually is caused by infiltration of incompressible materials into the joint space.

A process used to prevent joint reflective cracking in an HMA overlay over old PCC pavement.

The phenomenon when asphalt and water separate in an asphalt emulsion, which is the beginning of the curing process.

The practice of texturing a freshly placed PCC surface by dragging a stiff broom across it.

A bump or sag is a deviation in the surface elevation which impacts ride quality.

California Bearing Ratio. A strength test typically used on unconfined granular material.

A combination of cementitious material (usually portland cement), water and sand (fine aggregate). It does not include coarse aggregate.

A combination of cementitious material (usually portland cement) and water. It does not include any aggregate.

Having cementing properties (set and harden in the presence of water).

As HMA cools, the asphalt binder eventually becomes viscous enough to effectively prevent any further reduction in air voids regardless of the applied compactive effort.

Hairline surface cracks in an HMA mat caused by steel wheel rollers. Usually a result of over-compaction or attempting to compact the mat below cessation temperature.

Sprayed application of asphalt (usually emulsion, heated asphalt cement and cutbacks also used) followed by aggregate chips roller to achieve 50 to 70% embedment. Cost and performance depends on whether it is single or multi-course, as well as binder type and aggregate quality.

Cold In-Place Recycling. A general term for processes using grinding machines to recycle pavement into base material for new paving. CIR often uses additives such as emulsions or foamed asphalt for stabilization.

An intermediate substance in the production of portland cement. Made of heated calcium silicate, clinker is usually in the form of small gray-black pellets.

Defined by the Asphalt Institute (2001) as the fraction of aggregate retained on the No. 8 (2.36 mm) sieve. Defined by AASHTO M 147 as hard, durable particles or fragments of stone, gravel or slag retained on the No. 10 (2.00 mm) sieve.

A process in which a portion of an existing bituminous pavement is pulverized or milled, the reclaimed material is mixed with new binder and new materials, and the resultant blend is placed as a base for a subsequent overlay.

The combined effect of (1) applying weight to an HMA surface and compressing the material underneath the ground contact area and (2) creating a shear stress between the compressed material underneath the ground contact area and the adjacent uncompressed material.

Combination HMA and PCC pavements. Occasionally, they are initially constructed as composite pavements, but more frequently they are the result of pavement rehabilitation (e.g., HMA overlay of PCC pavement).

A sample made by combining and remixing several portions taken at intervals, so that it represents the whole batch or lot.

A set of aggregate properties including minimum angularity, flat or elongated particle and clay content requirements.

The process of making the freshly placed PCC into a more uniform and compact mass by eliminating undesirable air voids (entrapped air) and causing it to move around potential obstructions (such as reinforcing steel).

A discontinuity in a PCC pavement where placement has been halted for an extended period of time. For example, a construction joint is made when paving stops at the end of a work day. Construction joints can be placed both transversely and longitudinally.

The exact temperatures at which an asphalt binder just meets each performance grading criterion, found by interpolating between test temperatures.

A concrete pavement characterized by no transverse joints and continuous longitudinal reinforcement.

A sawed, formed, or tooled groove in a concrete slab that creates a weakened vertical plane. It regulates the location of the cracking caused by dimensional changes in the slab.

A crack in a jointed PCC pavement that intersects the joints at a distance less than or equal to one-half the slab length on both sides, measured from the corner of the slab.

Spalling is the breakdown of the concrete slab within approximately 0.5 m (1.5 ft.) of the corner or joint.

Corrugation, also known as “washboarding”, is a series of closely spaced ridges and valleys (ripples) occurring at fairly regular intervals, usually less than 3 m (10 ft) along the pavement. The ridges are perpendicular to the traffic direction.

Placement of adhesive material into and/over non-working cracks, minimal crack preparation, lower-quality materials used.

Placement of adhesive material into and/over working cracks, good crack preparation, high-quality materials used.

The result of the IDEAL-CT test on asphalt mixture, combining failure energy, post-peak slope and deformation tolerance. Higher means more crack resistant.

Continuously Reinforced Concrete Pavement. CRCP uses reinforcing steel for crack control. Cracks are allowed to form and held tightly together by underlying reinforcing steel.

Technique used to maintain load transfer across non-working longitudinal cracks that are in relatively good condition.

Unrefined petroleum.

The maintenance of satisfactory moisture and temperature within a PCC mass as it sets and hardens such that the desired properties of strength, durability and density can develop (from the Portland Cement Association).

Durability “D” cracking is caused by freeze-thaw expansion of the large aggregate, which, over time, gradually breaks down the concrete. This distress usually appears as a pattern of cracks running parallel and close to a joint or linear crack.

Dowel Bar Retrofit. Rehabilitation process performed on aged JPCP rigid pavements to reestablish load transfer between pavement slabs.

Refers to an HMA mix design using an aggregate gradation that is near the FHWA’s 0.45 power curve for maximum density. These are the most common HMA mix designs in the U.S.

Depressions are localized pavement surface areas with elevations slightly lower than those of the surrounding pavement.

Removal of thin concrete layer (0.12 to 0.25 in.) from pavement surface using special equipment.

Cutting narrow, discrete grooves (typically longitudinal) into pavement surface to increase friction and reduce noise.

Costs of an agency activity that are directly related to the quantity of work (e.g., labor, material, equipment usage, contract pay items).

A slab that is divided by cracks into four or more pieces due to overloading, or inadequate support, or both.

A device located across transverse joints at mid-depth of a PCC slab to provide load transfer from one slab to the adjoining slab. These are commonly smooth, round, and coated to resist corrosion.

Placement of dowel bars across joints or cracks in existing jointed concrete pavement.

A manufacturing facility for producing HMA. They manufacture HMA continuously rather than in batches.

A measure of how asphalt binder or PCC physical properties change with age. In general, as an asphalt binder ages, its viscosity increases and it becomes more stiff and brittle (sometimes called age hardening), and as a PCC ages freeze-thaw cycles and chemical attack degrade it.

Durability “D” cracking is caused by freeze-thaw expansion of the large aggregate, which, over time, gradually breaks down the concrete. This distress usually appears as a pattern of cracks running parallel and close to a joint or linear crack.

A measure of the viscosity of asphalt with respect to time, measured in poises, conducted at 60°C (140°F). (also called "absolute viscosity")

Edge cracks are parallel to and usually within 0.3 to 0.5 m (1 to 1.5 ft.) of the outer edge of the pavement. This distress is accelerated by traffic loading and can be caused by frost-weakened base or subgrade near the edge of the pavement.

The relationship between stress and strain within a material’s elastic range.

A substance used in asphalt emulsions to assist the formation of small asphalt cement globules in water by imparting an electrical charge to the surface of the asphalt cement globules so that they do not coalesce.

An emulsion of asphalt binder and water that contains a small amount of an emulsifying agent. Emulsified asphalt droplets may be of either the anionic (negative charge), cationic (positive charge) or nonionic (neutral).

Air included in PCC on purpose. Entrained air is usually added to mitigate the effects of freeze-thaw damage.

Air present in PCC but not included by design. Entrapped air usually is not sufficient to mitigate freeze-thaw damage due to its low volume and poor dispersion.

Cost of equipment used to perform maintenance events (rental or purchase).

ESAL is a concept developed from data collected at the American Association of State Highway Officials (AASHO) Road Test to establish a damage relationship for comparing the effects of axles carrying different loads.

Equivalent Single Axle Load. Based on the results from the AASHO Road Test, the most common approach to determining traffic loading is to convert wheel loads of various magnitudes and repetitions to an equivalent number of "standard" or "equivalent" loads.

An intentional discontinuity in a PCC pavement placed at a specific location to allow the pavement to expand without damaging adjacent structures or the pavement itself.

The pay a contractor can expect for consistently producing material at a particular quality level. Expected pay is not necessarily the same as the pay factor shown in the specification for that quality level.

A chart of moisture–density curves for the soils of one source, used to find the reference density from a single field-compacted point.

Alligator or fatigue cracking is a series of interconnecting cracks caused by fatigue failure of the asphalt concrete surface under repeated traffic loading.

Faulting is the difference in elevation across a joint or a crack.

Full-Depth Reclamation (full-depth CIR). FDR can be used to depths of 30 mm (12 inches) or more but the most typical applications involve depths of between 150 and 225 mm (6 and 9 inches).

Federal Highway Administration. Founded on 3 October 1893 as the Office of Road Inquiry, a small office of the U.S. Department of Agriculture. The Office of Road Inquiry was created to gather and disseminate information on road building.

A measure of the particle size of portland cement.

One of two chief methods of PCC paving. In fixed form paving, side forms are used to hold fresh PCC in place at the proper grade and alignment until it sets and hardens. These forms may also serve as tracks for various pieces of placing and finishing equipment.

The result of the I-FIT semicircular bend test on asphalt mixture: fracture energy divided by post-peak slope, scaled. Higher means more crack resistant.

A mixture of asphalt binder and aggregate thoroughly mixed and compacted into a mass.

Pavements that are surfaced with bituminous (or asphalt) materials as the surface course.

Running a flat surface across freshly placed PCC in order to eliminate high and low spots, embed larger aggregate particles beneath the surface, remove slight imperfections and compact the mortar at the surface in preparation for texturing (PCA, 1988).

A film of asphalt binder on the pavement surface caused by the upward migration of asphalt binder in an HMA pavement. (also called "bleeding")

A bituminous material, generally liquid, used for softening other bituminous materials.

Very light application of asphalt emulsion on pavement surface to seal the existing asphalt surface.

Durability “D” cracking is caused by freeze-thaw expansion of the large aggregate, which, over time, gradually breaks down the concrete. This distress usually appears as a pattern of cracks running parallel and close to a joint or linear crack.

An HMA pavement structure using HMA products for all components. The base material and surface courses are made of HMA instead of aggregate or other material.

Removal and replacement of deteriorated concrete through the full depth of the slab using approved repair materials; may be cast in-place of precast.

The classification used to group/categorize highway routes using a set of planning objectives that range from serving long-distance passenger and freight needs to serving neighborhood travel from residential developments to nearby shopping centers.

Used to improve the functional surface characteristics of the concrete pavement including enhancing friction and reducing noise. Consists of open or gap-graded aggregates and rubberized or polymer-modified asphalt layer (0.4 to 0.8 in. thick) well bonded to the concrete surface.

Falling Weight Deflectometer. The FWD is an impact load device used to deliver a transient impulse load to the pavement surface and measure the resultant pavement response (its deflection) by a series of sensors.

Fabric-like materials used in the paving process. Geotextiles are manufactured for specific uses and performance characteristics.

The distribution of particles of granular material among various sizes, usually expressed in terms of cumulative percentages larger or smaller than each of a series of sizes (sieve openings) or the percentages between certain ranges of sizes (sieve openings).

Granular material, such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast furnace slag, used with a hydraulic cementing medium to produce either concrete or mortar.

Generally "gravel borrow" refers to high quality granular fill. This granular fill may contain a substantial amount of soil but it is generally devoid of most clays/silts and other deleterious material.

Ground penetrating radar (GPR) is a noninvasive tool that has been used to map subsurface conditions in a wide variety of applications. Many of these applications are well suited for evaluation of highway systems to determine pavement thickness and condition.

An empirical number from the AASHTO soil classification that rates a soil within its group; it rises with fines content and plasticity.

Corrects surface distresses within top 2 in. of existing asphalt pavement by softening surface material through heat, mechanically loosening it, mixing with recycling agent, aggregate, rejuvenators, and/or virgin asphalt.

Corrects surface distresses within top 2 in. of existing asphalt pavement by softening surface material through heat, mechanically loosening it, mixing with recycling agent, aggregate, rejuvenators, and/or virgin asphalt.

Hot Mix Asphalt. A high quality, thoroughly controlled hot mixture of asphalt binder and aggregate that can be compacted into a uniform dense mass.

Used to treat localized distresses; partial-depth patches address surface distresses and full-depth patches address structural distresses.

Hot Mix Asphalt Concrete. Another term for HMA.

A plant-produced, high-quality hot mixture of asphalt cement and well-graded, high-quality aggregate thoroughly compacted into a uniform dense mass.

Corrects surface distresses within top 2 in. of existing asphalt pavement by softening surface material through heat, mechanically loosening it, mixing with recycling agent, aggregate, rejuvenators, and/or virgin asphalt.

Chemical reaction involving the addition of water. In portland cement, the chemical compound constituents undergo a series of chemical reactions in the presence of water that cause it to harden (or set).

An inorganic material or a mixture of inorganic materials that sets and develops strength by chemical reaction with water by formation of hydrates and is capable of doing so under water (from ASTM C 125 and the Portland Cement Association).

Subterranean ice crystals that form along the plane of freezing temperature. Water migrates up from below (where the temperature is above freezing) then freezes once it reaches the freezing depth in a soil forming an ice lens.

In place, in its original location.

A management tool that requires a third party, not directly responsible for process control or acceptance, to provide an independent assessment of the product and/or the reliability of test results obtained from process control and acceptance testing.

A measurement of the roughness of a pavement, expressed as the ratio of the accumulated suspension motion to the distance traveled obtained from a mathematical model of a standard quarter car traversing a measured profile at a speed of 50 mi/hr. (80 km/h).

An intentional discontinuity in a pavement used to lessen stresses that may develop due to differential movement between a pavement and a structure or another existing pavement.

Refers to properties that are the same regardless of the direction that is measured. Properties that are the same everywhere.

Job-Mix Formula. A recommended/specified mixture of aggregate and asphalt binder.

Nonrecoverable creep compliance from the MSCR test: the strain left after each load cycle divided by the stress. Lower values mean better rut resistance.

Cracks in a flexible overlay of a jointed rigid pavement. The cracks occur directly over the underlying rigid pavement joints.

Joint resealing consists of removing existing longitudinal/transverse joint sealants, preparing and installing new sealant material. Crack Sealing consists of cleaning, preparing and sealing longitudinal/transverse cracks.

Joint seal damage is any condition that enables soil or rocks to accumulate in the joints or allows significant water infiltration.

Spalling is the breakdown of the concrete slab within approximately 0.5 m (1.5 ft.) of the corner or joint.

A concrete pavement system characterized by short joint spacings and no reinforcement. Smooth dowels may be placed across the transverse joints to facilitate load transfer.

A concrete pavement system characterized by long joint spacings and containing steel mesh reinforcement distributed throughout the slab to hold any cracks tightly together.

Labor hours and unit rates to perform maintenance work (in-house and contractor), sum product of hours and unit cost.

Lane/shoulder drop-off is the difference between the settlement or erosion of the shoulder and the pavement travel-lane edge. The elevation difference can be a safety hazard, and it also can cause increased water infiltration.

A difference in elevation between the traffic lane and the shoulder.

The portion of the HMA paving process where the HMA is actually placed or "laid down" by the paving machine.

PCC that contains less portland cement paste than a typical PCC.

Load Equivalency Factor. The output from the ESAL equation. This factor relates various axle load combinations to the standard 80 kN (18,000 lb.) single axle load.

A first lift applied to an existing pavement used to fill in ruts and make up elevation differences.

A layer or course of paving material. Typically refers to flexible pavements. HMA is often placed in multiple layers based on compaction and smoothness considerations.

These cracks, which divide the slab into two or three pieces, usually are caused by a combination of repeated traffic loading, thermal gradient curling, and repeated moisture loading.

A material property meaning that an object or material will return to or is capable of returning to an initial form or state after deformation in a linear manner (e.g., a plot of a linear elastic material would show a straight line).

The water content above which a soil behaves as a viscous liquid (i.e. its shearing strength is negligible).

The installation of dowel bars or other mechanical devices at transverse joints or cracks in order to effectively transfer wheel loads across slabs and reduce deflections.

On asphalt pavements, these cracks are parallel or perpendicular to the pavement centerline or laydown direction. They may be caused by poorly constructed paving joints, asphalt shrinkage, or reflective cracking caused by cracking in the underlying surface. They are not usually load-associated.

These cracks, which divide the slab into two or three pieces, usually are caused by a combination of repeated traffic loading, thermal gradient curling, and repeated moisture loading.

An amount of material or items of similar origin grouped together for quality analysis purposes.

Type of early bituminous pavement named after its inventor, a Scotsman named John McAdam (1756 – 1836). McAdam (sometimes spelled "Macadam") pavements used smaller angular aggregate over larger angular aggregate over a well-compacted, sloped subgrade.

Non-polar or relatively low-polarity molecules within asphalt cement.

Map cracking or crazing refers to a network of shallow, fine, or hairline cracks that extend only through the upper surface of the concrete. The cracks tend to intersect at angles of 120°.

A term used to describe the fresh asphalt surface behind the paving machine. Most commonly used to refer to the asphalt during the placement and compaction phase of construction.

A term used to describe the pulling of the HMA under the screed of the paver. Generally results in coarse-textured streaks behind the paver.

Cost of materials used to perform the maintenance activity.

A term used to describe the estimated extent of PCC hydration by tracking time and temperature.

The highest dry density a soil reaches under a given laboratory compactive effort, found at the peak of its moisture–density (Proctor) curve.

Mix of crushed, well-graded aggregate, mineral filler, and latex-modified emulsified asphalt spread over entire pavement surface. Cost and performance depends on whether single, double, or multiple-course.

A process of removing pavement material from the surface of the pavement either to prepare the surface to receive overlays (by removing rutting and surface irregularities), to restore pavement cross slopes and profile, or to re-establish the pavement’s surface friction characteristics.

Finely divided mineral matter such as rock dust, slag dust, hydrated lime, hydraulic cement, fly ash, or cement kiln dust.

Material Transfer Vehicle. Used to assist the paver in accepting HMA. Most pavers are equipped to receive HMA directly, however in certain situations it can be necessary or advantageous to use an MTV.

A DSR test on RTFO-aged binder that applies repeated one-second creep loads at two stresses and measures recovery; the basis of AASHTO M 332 grading.

National Asphalt Pavement Association. NAPA supports an active research program designed to improve the quality of HMA pavements and paving techniques used in the construction of roads, streets, highways, parking lots, airports, and environmental and recreational facilities.

National Center for Asphalt Technology. NCAT was established at Auburn University in 1986 with an endowment set up by the NAPA Research and Education Foundation. Its mission is to improve HMA performance through research, education, and information services.

A fluid whose viscosity is constant at all shear rates. Since Isaac Newton first published the properties of an ideal fluid, ideal fluids are often called "Newtonian fluids".

Not Frost Susceptible.

A fluid whose viscosity is not constant at all shear rates. Some examples of non-Newtonian fluids are asphalt cement, cornstarch and water mixed together, ketchup and blood.

Sprayed application of asphalt (usually emulsion, heated asphalt cement and cutbacks also used) followed by aggregate chips roller to achieve 50 to 70% embedment. Cost and performance depends on whether it is single or multi-course, as well as binder type and aggregate quality.

In a soil, the moisture content at which maximum density can be achieved.

An adjustment to a laboratory maximum density and optimum moisture for coarse particles that were screened out of the laboratory test but present in the field.

Localized removal and replacement of deteriorated concrete, most often in vicinity of joints, in the upper third of the slab using approved repair materials.

A patch is an area of pavement that has been replaced with new material to repair the existing pavement. A patch is considered a defect no matter how well it is performing.

A patch is an area where the original pavement has been removed and replaced by filler material. A utility cut is a patch that has replaced the original pavement to allow the installation or maintenance of underground utilities.

A rating of pavement performance on a scale of 0 to 100, where 0 represents a failed pavement and 100 represents a pavement that is in excellent condition.

External indicators of pavement deterioration caused by loading, environmental factors, construction deficiencies, or a combination thereof. The severity levels are typically: low, medium, and high.

Layer of material in a pavement structure immediately beneath the base course.

The native soil prepared and compacted to support a pavement structure.

The top layer of a pavement structure.

The top layer of a pavement structure.

A multiple applied to the contract price of a particular item.

Portland Cement Concrete.

Percent Defective. The percentage of the lot falling outside specification limits.

In-place dry density expressed as a percentage of the maximum dry density from a specified laboratory test.

A property describing the degree to which a material can be permeated or penetrated, especially by liquids or gases.

Long-lasting HMA pavement.

The water content below which a soil ceases to behave as a plastic medium and begins to exhibit the properties of a semisolid.

The numerical difference between the Liquid Limit and the Plastic Limit of a soil.

French physiologist and physician (1797-1869). Person for whom "poise", a unit of viscosity, is named after. Best known for his research on the physiology of the circulation of blood through the arteries.

A molecule having a pair of electric charges or magnetic poles, of opposite sign or polarity, separated by a small distance. This is usually determined by the arrangement of atoms and relative electron location probabilities of the bonded molecule.

This distress is caused by repeated traffic applications. Polished aggregate is present when close examination of a pavement reveals that the portion of aggregate extending above the asphalt is either very small, or there are no rough or angular aggregate particles to provide good skid resistance.

A popout is a small piece of pavement that breaks loose from the surface due to freeze-thaw action, combined with expansive aggregates.

A hydraulic cement composed primarily of hydraulic calcium silicates (from the Portland Cement Association).

Potholes are small—usually less than 750 mm (30 in.) in diameter—bowl-shaped depressions in the pavement surface. They generally have sharp edges and vertical sides near the top of the hole.

A siliceous volcanic ash or artificial substance (such as fly ash) used to produce hydraulic cement.

A subjective rating of the pavement condition made by a group of individuals riding over the pavement, ranging from 0 (impassable) to 5 (perfect).

A planned strategy of cost-effective treatments to an existing roadway system and its appurtenances that preserves the system, retards future deterioration, and maintains or improves the functional condition of the system (without significantly increasing the structural capacity).

An application of asphalt primer to an absorbent surface. Often used to prepare an untreated base for an asphalt surface. The prime coat penetrates or is mixed into the surface of the base and plugs the voids, hardens the top and helps bind it to the overlying asphalt course.

Present Serviceability Index. A pavement condition index.

Present Serviceability Rating. A definition of pavement serviceability based on individual observation.

Pumping is the ejection of material from the slab foundation through joints or cracks. This is caused by deflection of the slab with passing loads.

This distress is a localized area of the slab that is broken into pieces. The punchout can take many different shapes and forms, but it is usually defined by a crack and a joint.

Percent Within Limits. The percentage of the lot falling above a lower specification limit, below an upper specification limit, or between upper and lower specification limits. PWL is related to PD by the following: PWL = 100% - PD.

In its broadest sense, quality is a degree of excellence: the extent to which something is fit for its purpose.

All those planned and systematic actions necessary to provide confidence that a product or facility will perform satisfactorily in service.

Those material characteristics or properties that a particular acceptance plan measures to determine quality.

Those quality assurance actions and considerations necessary to assess production and construction processes so as to control the level of quality being produced in the end product.

Railroad crossing distress is characterized by depressions or bumps around the tracks.

Reclaimed Asphalt Pavement. RAP is typically generated by (1) milling machines in rehabilitation projects or (2) a special crushing plant used to break down large pieces of discarded HMA pavement.

Raveling is the dislodging of coarse aggregate particles. Raveling may be caused by insufficient asphalt binder, poor mixture quality, insufficient compaction, segregation, or stripping.

Reclaimed Concrete Material. Same as RCP. When crushed, it can be used as a coarse aggregate in PCC, a granular base course or a fill/embankment material.

Recycled Concrete Pavement. Same as RCM. When crushed, it can be used as a coarse aggregate in PCC, a granular base course or a fill/embankment material.

Those that either expand or develop expansive by products when introduced to certain chemical compounds.

Pattern or map cracking (crazing) on the PCC slab surface caused by reactive aggregates.

PCC that is delivered to the customer in a freshly mixed and unhardened state (from the National Ready Mix Concrete Association).

This distress occurs only on asphalt-surfaced pavements that have been laid over a concrete slab.

The yield of a concrete batch divided by the volume it was designed or ordered to produce. Below 1.00 means the batch is short.

In petroleum refining, they are the left-overs from the refining process.

An estimate of a material’s elastic modulus based on stress and strain measurements from rapidly applied loads – like those that pavement materials experience from wheel loads.

Eliminated from Superpave specifications in late 2002. A particular area of the FHWA’s 0.45 power gradation graph associated with Superpave mix designs. It was observed that mixes closely following the 0.45 power maximum density line sometimes had unacceptably low VMA.

Technique used to collect water that has infiltrated into the pavement structure and discharges it to the ditches through regularly spaced outlet drains. Can have negative impact if creates "bathtub" through poor design or construction.

Recycled Hot Mix.

The theoretical maximum density of an HMA if it contained zero air voids. (also called "TMD")

A measurement of the roughness of a pavement, expressed as the ratio of the accumulated suspension motion to the distance traveled obtained from a mathematical model of a standard quarter car traversing a measured profile at a speed of 50 mi/hr. (80 km/h).

Pavements that are surfaced with PCC in the surface course. Since PCC has a high modulus of elasticity, rigid pavements do not flex appreciably to accommodate traffic loads.

A self-propelled machine having a transverse cutting and mixing head inside of a closed chamber for the pulverization and mixing of existing pavement materials with asphalt emulsion.

Distortions of the road surface that contribute to an undesirable, unsafe, uneconomical, or uncomfortable ride.

Rejectable Quality Limit. The maximum level of actual quality at which a material or construction can be considered unacceptable and thus, rejectable.

Reducing a material or structure to rubble. Regarding pavements, rubblization usually refers to reducing an existing rigid pavement to rubble in preparation for an HMA overlay. This helps prevent reflective cracking in the new overlay.

A rut is a surface depression in the wheel paths.

The use of compressed air to blast a surface with an abrasive medium (sand) for quickly preparing the surfacing for repair.

The part of a paving machine that spreads, smoothes, and provides initial compaction.

A process in PCC paving where excess portions of the roughly placed PCC are cut off in order to bring the slab to the required elevation. This is usually done by dragging a straightedge across the slab at the required elevation.

Sprayed application of asphalt (usually emulsion, heated asphalt cement and cutbacks also used) followed by aggregate chips roller to achieve 50 to 70% embedment. Cost and performance depends on whether it is single or multi-course, as well as binder type and aggregate quality.

Regarding HMA, the broad definition is "a lack of homogeneity in the hot mix asphalt constituents of the in-place mat of such a magnitude that there is a reasonable expectation of accelerated pavement distress(es)." Typically though, "segregation" refers to aggregate…

State Highway Association.

A slab that is divided by cracks into four or more pieces due to overloading, or inadequate support, or both.

To undergo plastic deformation and movement without cracking or breaking.

Steel wheel roller with large protrusions on the drum used for soil compaction.

The "father of modern quality control". Shewhart successfully brought together the disciplines of statistics, engineering, and economics and became known as the father of modern quality control.

Shoving is a permanent, longitudinal displacement of a localized area of the pavement surface caused by traffic loading.

Shrinkage cracks are hairline cracks that usually are less than 2-m long and do not extend across the entire concrete slab.

Strategic Highway Research Plan.

Slab stabilization involves the restoration of support to slabs by filling voids, thereby reducing deflections. Slab jacking involves raising slabs to their desired elevation by pressure inserting material beneath settled slabs.

Slippage cracks are crescent or half-moon shaped cracks, usually transverse to the direction of travel. They are produced when braking or turning wheels cause the pavement surface to slide or deform.

A mixture of quick- or slow-setting emulsified asphalt, well-graded fine aggregate, mineral filler, and water. It is used to fill cracks and seal areas of bituminous A mixture of quick- or slow-setting emulsified asphalt, well-graded fine aggregate, mineral filler, and water.

One sample divided into portions tested by different parties or laboratories, to compare their testing rather than the material.

Granular material, such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast furnace slag, used with a hydraulic cementing medium to produce either concrete or mortar.

The top layer of a pavement structure.

The retarding force developed at the tire-pavement interface that resists sliding when braking forces are applied to the vehicle tires.

The top layer of a pavement structure.

The characteristics of the pavement surface that contribute to both surface friction and noise. Surface texture is comprised of microtexture and macrotexture.

Swell is characterized by an upward bulge in the pavement’s surface, a long, gradual wave more than 3 m (10 ft.) long.

On asphalt pavements, these cracks are parallel or perpendicular to the pavement centerline or laydown direction. They may be caused by poorly constructed paving joints, asphalt shrinkage, or reflective cracking caused by cracking in the underlying surface. They are not usually load-associated.

Used to improve the functional surface characteristics of the concrete pavement including enhancing friction and reducing noise. Consists of open or gap-graded aggregates and rubberized or polymer-modified asphalt layer (0.4 to 0.8 in. thick) well bonded to the concrete surface.

A thin [50 to 100 mm (2 to 4 in)] PCC overlay of an existing HMA pavement. UTW is a functional overlay that provides a stable surface that is resistant to deformation from static, slow moving, and turning loads.

Used to improve the functional surface characteristics of the concrete pavement including enhancing friction and reducing noise. Consists of open or gap-graded aggregates and rubberized or polymer-modified asphalt layer (0.4 to 0.8 in. thick) well bonded to the concrete surface.

Used to improve the functional surface characteristics of the concrete pavement including enhancing friction and reducing noise. Consists of open or gap-graded aggregates and rubberized or polymer-modified asphalt layer (0.4 to 0.8 in. thick) well bonded to the concrete surface.

The time-frame (usually in years) over which an analysis (e.g. LCCA, LCA) is performed.

These cracks, which divide the slab into two or three pieces, usually are caused by a combination of repeated traffic loading, thermal gradient curling, and repeated moisture loading.

The total cost of applying a maintenance treatment (includes labor, equipment, materials, pay items, traffic mobilization, and overhead costs).

May be used as an alternative to chip-seals, microsurfacing, or thin overlays. Consists of a open-graded or gap-graded, polymer-or rubber-modified asphalt layer (0.4 to 0.8 in. thick) placed on a heavy tack coat.

An HMA overlay over an existing HMA or PCC pavement and is less than 25 mm (1 in) in thickness. May also be called a thin bonded wearing course.

A thin [50 to 100 mm (2 to 4 in)] PCC overlay of an existing HMA pavement. UTW is a functional overlay that provides a stable surface that is resistant to deformation from static, slow moving, and turning loads.

An HMA overlay over an existing HMA or PCC pavement and is less than 25 mm (1 in) in thickness. May also be called a thin bonded wearing course.

Warm-mix asphalt technologies allow the producers of asphalt pavement material to lower the temperatures (50 to 100° F lower) at which the material is mixed and placed on the road.

The mass of water in a concrete mix divided by the mass of all cementitious materials: portland cement plus fly ash, slag and other pozzolans.

The top layer of a pavement structure.

The wearing away of the asphalt binder and fine aggregate matrix.

The top layer of a pavement structure.

The volume of fresh concrete a batch actually produces: the total mass of the batched materials divided by the measured density.

The dry density a soil would have at each water content if all its voids were filled with water. No compacted point can plot above it.