Glossary

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  • a

  • AASHTO
    American Association of State Highway and Transportation Officials

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

  • AC Patching
    Used to treat localized distresses; partial-depth patches address surface distresses and full-depth patches address structural distresses. Also referred to as Patching, HMA Patching, Asphalt Patching.

  • Acceptance
    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.

  • ACI
    American Concrete Institute. A nonprofit scientific and educational society, organized in 1904, to represent the user interest in the concrete field. ACI defines “user” as “the public agency, engineer, architect, owner, contractor, educator, or other specialist interested in the design, construction or maintenance of concrete structures.” ACI’s purpose is “to provide a comradeship in finding the best ways to do concrete work of all kinds and in spreading that knowledge.” (from the ACI website) http://www.aci-int.org

  • ACPA
    American Concrete Pavement Association. A national association representing concrete pavement contractors, cement companies, equipment and material manufacturers and suppliers. It is organized to address common needs, solve common problems, and accomplish goals related to research, market development, local promotion, design, construction and best practices of PCC pavements. http://www.pavement.com

  • Admixture
    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.

  • Agency Cost
    Costs of an agency activity that are directly related to the quantity of work (e.g., labor, material, equipment usage, contract pay items). Also referred to as Direct Cost.

  • Aggregate
    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. Also referred to as Stone, Gravel.

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

  • Aggregate 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). Also referred to as Gradation.

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

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

  • Alkali-aggregate reaction
    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.

  • Alkali Silica Reaction (ASR)
    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.

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

  • Analysis Period
    The time-frame (usually in years) over which an analysis (e.g. LCCA, LCA) is performed. Also referred to as Time Period.

  • Annual Average Daily Traffic (AADT)
    Total volume of vehicle traffic of a highway or road for a year divided by 365 days.

  • APA
    Asphalt Pavement Alliance. A coalition of the Asphalt Institute, the National Asphalt Pavement Association, and the State Asphalt Pavement Associations. The Asphalt Pavement Alliance's mission is to further the use and quality of Hot Mix Asphalt pavements through research, technology transfer, engineering, education and innovation. http://www.asphaltalliance.com

  • API Gravity
    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).

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

  • AREA Parameter
    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)

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

  • Asphalt Binder
    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.

  • Asphalt Cement
    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.

  • Asphalt Concrete
    A mixture of asphalt binder and aggregate thoroughly mixed and compacted into a mass. Also referred to as Bituminous Concrete, Flexible Pavement.

  • Asphalt Emulsion
    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). Also referred to as Emulsion, Bituminous Emulsion.

  • Asphalt Institute
    A U.S.-based association of international petroleum asphalt/bitumen producers, manufacturers, and affiliated business. Its mission is to promote the use, benefits, and quality performance of petroleum asphalt, through environmental, marketing, research, engineering and technical development, and through the resolution of issues affecting the industry. http://www.asphaltinstitute.org

  • Asphalt Patching
    Used to treat localized distresses; partial-depth patches address surface distresses and full-depth patches address structural distresses. Also referred to as Patching, HMA Patching, AC Patching.

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

  • b

  • Backcalculation
    A mechanistic evaluation of pavement surface deflection basins generated by various pavement deflection devices. Backcalculation takes a measured surface deflection and attempts to match it (to within some tolerable error) with a calculated surface deflection generated from an identical pavement structure using assumed layer stiffnesses (moduli).

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

  • Base 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.

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

  • Bitumens
    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.

  • Bituminous Concrete
    A mixture of asphalt binder and aggregate thoroughly mixed and compacted into a mass. Also referred to as Bituminous Concrete, Flexible Pavement.

  • Bituminous Emulsion
    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). Also referred to as Emulsion, Bituminous Emulsion.

  • Bleeding
    Bleeding is a film of bituminous material on the pavement surface that creates a shiny, glasslike, reflecting surface that usually becomes quite sticky. Bleeding is caused by excessive amounts of asphaltic cement or tars in the mix, excess application of a bituminous sealant, or low air void content, or a combination thereof.

  • Block Cracking
    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.). Block cracking is caused mainly by shrinkage of the asphalt concrete and daily temperature cycling, which results in daily stress/strain cycling. It is not load-associated.

  • Blowup and Buckling
    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.

  • Break and seat
    A process used to prevent joint reflective cracking in an HMA overlay over old PCC pavement. It involves breaking up the underlying rigid pavement into relatively small pieces (on the order of about 0.3 m<sup>2</sup> to 0.6 m<sup>2</sup> (1 ft<sup>2</sup> to 2 ft<sup>2</sup>) by repeatedly dropping a large weight. The pieces are then seated by 2 to 3 passes of a large rubber tired roller.

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

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

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

  • c

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

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

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

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

  • Cessation temperature
    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. As a rule-of-thumb the temperature at which this occurs, commonly referred to as cessation temperature, is about 79°C (175°F) for dense-graded HMA. The grade of PG binder is known to have somewhat of an effect on cessation temperature.

  • Checking
    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.

  • Chip Seals
    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. This is also referred to as emulsion, cutback, asphalt cement, with polymer or rubber. Also referred to as Oil and Chip, Seal Coat.

  • CIR
    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.

  • Clinker
    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. Clinker is subsequently cooled and pulverized into a fine powder that almost completely passes through a 0.075 mm (No. 200) sieve and fortified with a small amount of gypsum to form portland cement.

  • Coarse Aggregate
    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.

  • Cold-in-place recycling
    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.

  • Compactive effort
    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.

  • Composite pavements
    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). Officially, the FHWA "composite pavement" category is defined as a "mixed bituminous or bituminous penetration roadway" of more than 25 mm (1 inch) of compacted material on a rigid base (from the FHWA).

  • Consensus requirements (properties)
    A set of aggregate properties including minimum angularity, flat or elongated particle and clay content requirements. These requirements came about because SHRP did not specifically address aggregate properties and it was thought that there needed to be some aggregate property guidance associated with the Superpave mix design method. Therefore, an expert group on aggregate properties was convened and arrived at a consensus on several aggregate property requirements.

  • Consolidation
    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). Sometimes this process is referred to as "compaction" however this Guide attempts to make a distinction between <em>consolidating</em> PCC and <em>compacting</em> HMA - two very different processes.

  • Construction joint
    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.

  • Continuously Reinforced Concrete Pavement (CRCP)
    A concrete pavement characterized by no transverse joints and continuous longitudinal reinforcement.

  • Contraction joint
    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.

  • Corner Break
    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.

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

  • Corrugation
    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. This type of distress usually is caused by traffic action combined with an unstable pavement surface or base.

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

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

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

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

  • Crude Oil
    Unrefined petroleum.

  • Curing
    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).

  • d

  • D Cracking
    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. Also referred to as D Cracking, Freeze-Thaw Damage.

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

  • Dense-graded mix
    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.

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

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

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

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

  • Divided Slab
    A slab that is divided by cracks into four or more pieces due to overloading, or inadequate support, or both. Also referred to as Shattered Slab.

  • Dowel Bar
    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.

  • Dowel Bar Retrofit
    Placement of dowel bars across joints or cracks in existing jointed concrete pavement.

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

  • Durability
    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 Cracking
    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. Also referred to as D Cracking, Freeze-Thaw Damage.

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

  • e

  • Edge Cracking
    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.

  • Elastic modulus
    The relationship between stress and strain within a material’s elastic range. Thus, the "flexibility" of any object depends on its elastic modulus and geometric shape; however, it is important to note that strength (stress needed to break something) is not the same thing as stiffness (as measured by elastic modulus).

  • Emulsifying agent
    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.

  • Emulsion
    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). Also referred to as Emulsion, Bituminous Emulsion.

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

  • Entrapped air
    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.

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

  • Equivalent Single Axle Load (ESAL)
    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.

  • ESAL
    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. The most commonly used equivalent load in the U.S. is the 80 kN (18,000 lbs.) equivalent single axle load.

  • Expansion joint
    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.

  • Expected pay
    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.

  • f

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

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

  • FDR
    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).

  • FHWA
    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. The office grew from just two employees to about 3,500 and its annual budget grew from $10,000 to more than $26 billion. The office is now known as the Federal Highway Administration (FHWA) and is part of the U.S. Department of Transportation, which was formed in 1967. http://www.fhwa.dot.gov/ctdiv/history.htm

  • Fineness
    A measure of the particle size of portland cement.

  • Fixed form PCC paving
    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.

  • Flexible Pavement
    A mixture of asphalt binder and aggregate thoroughly mixed and compacted into a mass. Also referred to as Bituminous Concrete, Flexible Pavement.

  • Flexible pavement
    Pavements that are surfaced with bituminous (or asphalt) materials as the surface course. These can be either in the form of pavement surfaces such as a bituminous surface treatment (BST) generally found on lower volume (or lower traffic) roads, or hot mix asphalt (HMA) surfaces generally used on higher volume roads. These types of pavements are called "flexible" since the total pavement structure "bends" or "deflects" due to traffic loads.

  • Floating
    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).

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

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

  • Fog Seal/Rejuvenators
    Very light application of asphalt emulsion on pavement surface to seal the existing asphalt surface.

  • Freeze-Thaw Damage
    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. Also referred to as D Cracking, Freeze-Thaw Damage.

  • Full-depth asphalt
    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.

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

  • Functional Classification
    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.

  • Functional Overlay
    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. Also referred to as Thin Overlay, Thin HMA Overlay, Functional Overlay, Ultra Thin Bonded Wearing Course.

  • FWD
    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.

  • g

  • Geotextiles
    Fabric-like materials used in the paving process. Geotextiles are manufactured for specific uses and performance characteristics. Some uses include stabilization of base material to prevent migration of fines from the subgrade into the base material, retarding of reflective cracking in asphalt overlays, and serving as a moisture barrier between pavement layers (NPCA).

  • 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). Also referred to as Gradation.

  • Gravel
    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. Also referred to as Stone, Gravel.

  • Gravel borrow
    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
    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. GPR is basically a subsurface “anomaly” detector, as such it will map changes in the underground profile due to contrasts in the electromagnetic conductivity across material interfaces. In a GPR system, short pulses of radio wave energy travel through the pavement structure and create echos at boundaries of dissimilar materials, such as at an asphalt-base interface.

  • h

  • HIPR
    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. Also referred to as HIR, HIPR.

  • HIR
    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. Also referred to as HIR, HIPR.

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

  • HMA Patching
    Used to treat localized distresses; partial-depth patches address surface distresses and full-depth patches address structural distresses. Also referred to as Patching, HMA Patching, AC Patching.

  • HMAC
    Hot Mix Asphalt Concrete. Another term for HMA.

  • Hot-in-place recycling
    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. Also referred to as HIR, HIPR.

  • Hot Mix Asphalt (HMA)
    A plant-produced, high-quality hot mixture of asphalt cement and well-graded, high-quality aggregate thoroughly compacted into a uniform dense mass. Also referred to as Asphalt Concrete.

  • Hydration
    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).

  • Hydraulic cement
    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).

  • i

  • Ice lens
    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-situ
    In place, in its original location.

  • Independent assurance
    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. The results of independent assurance tests are not to be used as a basis of product acceptance.

  • International Roughness Index (IRI)
    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).

  • Isolation joint
    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.

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

  • j

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

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

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

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

  • Jointed Plain Concrete Pavement (JPCP)
    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.

  • Jointed Reinforced Concrete Pavement (JRCP)
    A concrete pavement system characterized by long joint spacings and containing steel mesh reinforcement distributed throughout the slab to hold any cracks tightly together.

  • l

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

  • Lane-shoulder drop-off
    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.

  • Lane/shoulder drop-off
    A difference in elevation between the traffic lane and the shoulder.

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

  • Lean concrete
    PCC that contains less portland cement paste than a typical PCC.

  • LEF
    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.

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

  • Lift
    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.

  • Linear cracking (longitudinal, transverse, and diagonal)
    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. Also referred to as Longitudinal Cracking, Transverse Cracking.

  • Linear elastic
    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). Almost no material is completely linearly elastic but many materials are linearly elastic over a certain range of stress/strain.

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

  • Load transfer retrofit
    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.

  • Longitudinal and Transverse Cracking (not reflective)
    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. Also referred to as Longitudinal Cracking, Transverse Cracking, Thermal Cracking.

  • Longitudinal Cracking
    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. Also referred to as Longitudinal Cracking, Transverse Cracking.

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

  • m

  • Macadam
    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.

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

  • Map Cracking and Scaling
    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°. Map cracking or crazing usually is caused by concrete over-finishing and may lead to surface scaling, which is the breakdown of the slab surface to a depth of approximately 6 to 13 mm (1⁄4 to 1⁄2 in.).

  • Mat
    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.

  • Mat tearing
    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.

  • Material Cost
    Cost of materials used to perform the maintenance activity.

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

  • Microsurfacing
    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.

  • Milling
    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.

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

  • MTV
    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. Paving using bottom dump trucks and windrows requires a windrow elevator MTV while other MTVs are used to provide additional surge volume allowing the paver to operate continuously without stopping, minimizing truck waiting time at the paving site and minimizing segregation and temperature differentials.

  • n

  • NAPA
    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. The Association provides technical, educational, and marketing materials and information to its Members, as well as product information to users and specifiers of paving materials. The Association, whose members number more than 1,100 companies, was founded in 1955.

  • NCAT
    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.

  • Newtonian fluid
    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".

  • NFS
    Not Frost Susceptible.

  • Non-Newtonian fluid
    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.

  • o

  • Oil and Chip
    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. This is also referred to as emulsion, cutback, asphalt cement, with polymer or rubber. Also referred to as Oil and Chip, Seal Coat.

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

  • p

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

  • Patching
    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. Also referred to as Asphalt Patching.

  • Patching and utility cuts
    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. The severity levels of a utility cut are assessed according to the same criteria as large patching.

  • Pavement Condition Index (PCI)
    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.

  • Pavement Distress
    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.

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

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

  • Pavement Surface
    The top layer of a pavement structure. Also referred to as Pavement Surface, Surface Course, Surface Layer, Wearing Course, Weathering Course.

  • Pavement Wearing Course
    The top layer of a pavement structure. Also referred to as Pavement Surface, Surface Course, Surface Layer, Wearing Course, Weathering Course.

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

  • PCC
    Portland Cement Concrete.

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

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

  • Perpetual pavement
    Long-lasting HMA pavement.

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

  • Plasticity index (PI)
    The numerical difference between the Liquid Limit and the Plastic Limit of a soil.

  • Poiseuille, Jean Louis Marie
    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. His interest in blood circulation led him to study the flow rates of other fluids. In 1840 he formulated the law regarding the flow rate for the laminar flow of fluids in circular tubes. In 1847 he published the results of further experiments using ether and mercury. Gotthilf Hagen, a German hydraulic engineer, discovered Poiseuille's law independently in 1839. (from Atomica)

  • Polar molecule
    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.

  • Polished Aggregate
    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.

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

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

  • Pothole
    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.

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

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

  • Preventive Maintenance
    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).

  • Prime coat
    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.

  • PSI
    Present Serviceability Index. A pavement condition index.

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

  • Pumping
    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.

  • Punchout
    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.

  • PWL
    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.

  • q

  • Quality
    In its broadest sense, quality is a degree of excellence: the extent to which something is fit for its purpose. In the narrow sense, product or service quality is defined as conformance with requirement, freedom from defects or contamination, or simply a degree of customer satisfaction. In quality management, quality is defined as the totality of characteristics of a product or service that bears on its ability to satisfy stated and implied needs (from the Institute of Quality Assurance). In statistical acceptance plans "quality" is narrowly defined as the fraction of the overall quality characteristic distribution that falls within specification limits.

  • Quality assurance
    All those planned and systematic actions necessary to provide confidence that a product or facility will perform satisfactorily in service. Quality assurance addresses the overall problem of obtaining the quality of a service, product, or facility in the most efficient, economical, and satisfactory manner possible. Within this broad context, quality assurance involves continued evaluation of the activities of planning, design, development of plans and specifications, advertising and awarding of contracts, construction, and maintenance, and the interactions of these activities. Note that this definition is not always consistent with other quality assurance definitions.

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

  • Quality Control
    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. This concept of quality control includes sampling and testing to monitor the process but usually does not include acceptance sampling and testing. Also called process control.

  • r

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

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

  • RCM
    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.

  • RCP
    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.

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

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

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

  • Reflection Cracking
    This distress occurs only on asphalt-surfaced pavements that have been laid over a concrete slab. It does not include reflection cracks from any other type of base, that is, cement- or lime-stabilized; these cracks are caused mainly by thermal- or moisture-induced movement of the concrete slab beneath the AC surface. This distress is not load-related; however, traffic loading may cause a breakdown of the asphalt surface near the crack.

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

  • Resilient Modulus
    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.

  • Restricted zone
    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. Therefore, Superpave introduced a restricted zone through which a typical gradation should not pass. By avoiding the restricted zone, mixes should have sufficient VMA to allow enough asphalt for adequate durability.

  • Retrofitted Edge Drains
    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.

  • RHM
    Recycled Hot Mix.

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

  • Ride Quality
    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).

  • Rigid Pavement
    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.

  • Road reclaimer
    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.

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

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

  • Rubblization
    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.

  • Rutting
    A rut is a surface depression in the wheel paths.

  • s

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

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

  • Screeding
    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.

  • Seal Coat
    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. This is also referred to as emulsion, cutback, asphalt cement, with polymer or rubber. Also referred to as Oil and Chip, Seal Coat.

  • Segregation
    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 segregation, which is "the non-uniform distribution of coarse and fine aggregate components within the asphalt mixture."

  • SHA
    State Highway Association.

  • Shattered Slab
    A slab that is divided by cracks into four or more pieces due to overloading, or inadequate support, or both. Also referred to as Divided Slab.

  • Shear Flow
    To undergo plastic deformation and movement without cracking or breaking.

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

  • Shewhart, Dr. Walter A.
    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. The lasting and tangible evidence of that union for which he is most widely known is the control chart, a simple but highly effective tool that represented an initial step toward what he called "the formulation of a scientific basis for securing economic control." (from the American Society for Quality web site).

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

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

  • SHRP
    Strategic Highway Research Plan.

  • Slab Stabilization/Slab Jacking
    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 Cracking
    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.

  • Slurry Seal
    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. It is used to fill cracks and seal areas of bituminous.

  • Stone
    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. Also referred to as Stone, Gravel.

  • Surface Course
    The top layer of a pavement structure. Also referred to as Pavement Surface, Surface Course, Surface Layer, Wearing Course, Weathering Course.

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

  • Surface Layer
    The top layer of a pavement structure. Also referred to as Pavement Surface, Surface Course, Surface Layer, Wearing Course, Weathering Course.

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

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

  • t

  • Thermal Cracking
    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. Also referred to as Longitudinal Cracking, Transverse Cracking, Thermal Cracking.

  • Thin asphalt overlays
    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. Also referred to as Thin Overlay, Thin HMA Overlay, Functional Overlay, Ultra Thin Bonded Wearing Course.

  • Thin Concrete Overlay
    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.

  • Thin HMA Overlay
    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. Also referred to as Thin Overlay, Thin HMA Overlay, Functional Overlay, Ultra Thin Bonded Wearing Course.

  • Thin Overlay
    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. Also referred to as Thin asphalt overlays.

  • Time Period
    The time-frame (usually in years) over which an analysis (e.g. LCCA, LCA) is performed. Also referred to as Time Period.

  • Transverse Cracking
    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. Also referred to as Longitudinal Cracking, Transverse Cracking.

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

  • u

  • Ultra-thin bonded wearing course
    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.

  • Ultra-thin overlay
    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. Also referred to as Thin Overlay, UT Overlay, Functional Overlay, Ultra-thin bonded wearing course.

  • Ultra-thin whitetopping (UTW)
    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.

  • UT Overlay
    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. Also referred to as Thin Overlay, UT Overlay, Functional Overlay, Ultra-thin bonded wearing course.

  • w

  • Warm Mix Asphalt (WMA)
    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.

  • Wearing Course
    The top layer of a pavement structure. Also referred to as Pavement Surface, Surface Course, Surface Layer, Wearing Course, Weathering Course.

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

  • Weathering Course
    The top layer of a pavement structure. Also referred to as Pavement Surface, Surface Course, Surface Layer, Wearing Course, Weathering Course.