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81 Agency cost: Costs to an agency of an activity that are directly related to the quantity of work (e.g., labor, material, equipment usage, contract pay items) (AASHTO) (1). 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, or used with asphalt cement to produce asphalt concrete, or used in the base and/or subbase layers of a pavement structure (CPTC 2007) (9). Also referred to as stone, gravel. 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) (CPTC 2007) (9). Also referred to as gradation. Alkali silica reaction (ASR): The reaction between the alkalis (sodium and potassium) in Portland cement binder and certain siliceous rocks or minerals, such as opaline chert, strained quartz, and acidic volcanic glass, present in some aggregates; the products of the reaction may cause abnormal expansion and cracking of concrete in service (ASTM D5340) (4). Alligator cracking: A series of interconnecting cracks in the surface of an asphalt concrete pave- ment caused by fatigue failure under repeated traffic loading (ASTM D6433) (3). Also referred to as fatigue cracking. Annual average daily traffic (AADT): Total volume of vehicle traffic of a highway or road for a year divided by 365 days. Asphalt concrete: A mixture of asphalt binder and aggregate thoroughly mixed and compacted into a mass (AI) (2). Also referred to as bituminous concrete, flexible pavement, hot-mix asphalt. Asphalt emulsion: A blend 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) (AI) (2). Also referred to as emulsion, bituminous emulsion. Asphalt patching: Replacement of a localized area of pavement. Used to treat localized distresses; partial-depth patches address surface distresses and full-depth patches address structural distresses (SHRP 2) (15). Also referred to as patching, HMA patching, asphalt concrete patching. Base: The layer of material immediately beneath the pavement surface or binder course (AI) (2). 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 (CPTC 2007) (9). Glossary
82 Framework for a Pavement-Maintenance Database System Bleeding: The formation of a film of asphalt 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 an asphalt-based crack sealant, excess application of a tack coat, low air void content, or a combination thereof (ASTM 6433) (3). Block cracking: Interconnected cracks that divide the pavement into approximately rectangular pieces. The blocks may range in size from approximately 1 by 1 ft. (0.3 by 0.3 m) to 10 by 10 ft. (3 by 3 m). Block cracking is caused mainly by shrinkage of the asphalt concrete and daily tem- perature cycling, which results in daily stress/strain cycling. It is not associated with pavement loading (ASTM 6433) (3). Blow up and buckling: Vertical pavement deformations that usually 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 (ASTM 6433) (3). Chip seals: Sprayed application of asphalt (usually emulsion, although heated asphalt cement and cutbacks are also used) followed by aggregate chips rolled to achieve 50% to 70% embed- ment. Different types of chip seals are obtained by varying the binder, the aggregate, or by placing multiple courses (NCHRP 342) (17). Also referred to as oil and chip, seal coat, surface treatment. Cold-in-place recycling: Milling and sizing reclaimed asphalt pavement (RAP) and mixing in-place with recycling additive and new aggregate which is then re-laid and compacted as new base course. Cold-in-place recycling requires that a new surface be placed over it, usually an asphalt overlay or other surface treatment (ARRA) (NCHRP 342). Continuously reinforced concrete pavement (CRCP): A concrete pavement characterized by no transverse joints and continuous longitudinal reinforcement (CPTC 2007) (9). 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 (ASTM 6433) (3). Crack filling: Placement of adhesive material into and over non-working cracks. Often character- ized by minimal crack preparation and use of lower-quality sealant materials (NCHRP 784) (11). Crack sealing: Placement of adhesive material into and over working cracks. Often characterized by good crack preparation and the use of high-quality sealant materials (CPTC 2008) (10). Cross stitching: Technique used to maintain load transfer across non-working longitudinal cracks in concrete pavements that are in relatively good condition (CPTC 2008) (10). Depression: Localized areas of the pavement surface with elevations slightly lower than those of the surrounding pavement (ASTM 6433) (3). Diamond grinding: Removal of thin concrete layer (0.12 in. to 0.25 in.) from pavement surface using special equipment outfitted with diamond-tipped saw blades (CPTC 2008) (10). Diamond grooving: Cutting narrow, discrete grooves (typically longitudinal) into pavement surface to increase tire-pavement contact when surface is wet and to reduce noise (CPTC 2008) (10). Dowel bar: A device placed across transverse joints at mid-depth of a PCC slab to transfer load from one slab to the adjoining slab. These are commonly smooth, round steel bars that are coated to resist corrosion (CPTC 2007) (9). Dowel bar retrofit (DBR): Placement of dowel bars across joints or cracks in existing jointed concrete pavement (SHRP 2) (15). Durability cracking: A failure mechanism in concrete in which the freezeâthaw expansion of the large aggregate, over time, gradually breaks down the concrete. This distress usually begins
Glossary 83 at the bottom of the slab and appears as a pattern of cracks running parallel and close to a joint or linear crack (ASTM 6433) (3). Also referred to as D cracking, freezeâthaw damage. Edge cracking: A pattern of distress in asphalt pavements which runs parallel to and usually within 1 to 1.5 ft. (0.3 m to 0.5 m) 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 (ASTM 6433) (3). Equipment cost: A value assigned to equipment as part of an overall life-cycle cost calculation. It may be a rental cost or an ownership cost spread over the expected life of the equipment. 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. Faulting: The difference in elevation across a transverse discontinuity, such as a joint or a crack (ASTM 6433) (3). Fog seal: Very light application of asphalt emulsion to seal an existing asphalt surface (SHRP 2) (15). Full-depth asphalt pavement: The term full-depth (registered by the Asphalt Institute with the U.S. Patent Office) certifies that the pavement is one in which asphalt mixtures are employed for all courses above the subgrade or improved subgrade. A full-depth asphalt pavement is placed directly on the prepared subgrade (AI) (2). 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 or precast (CPTC 2008) (10). Functional classification: A way of grouping or categorizing 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 (FHWA) (6). Hot-in-place recycling: The removal and replacement of a portion of the surface of an existing asphalt pavement to correct surface distresses within top 2 inches (51 mm). The pavement surface is softened by heat, mechanically loosened, picked up and mixed with recycling agent, aggregate, rejuvenators, and/or virgin asphalt, and then relayed (ARRA 2001) (NCHRP 342). 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 (AI) (2). Also referred to as asphalt concrete. International Roughness Index (IRI): A measurement of the longitudinal profile 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/h (80 km/h) (ASTM E1926). Joint reflection cracking: The projection through the surface of an HMA pavement of a joint in an underlying layer of a PCC pavement. This 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 (ASTM 6433) (3). Joint resealing: Removal of existing longitudinal/transverse joint sealants, preparing and install- ing new sealant material (CPTC 2008) (10).
84 Framework for a Pavement-Maintenance Database System Joint seal damage: Any condition involving failure of the sealant in a concrete pavement that enables soil or rocks to accumulate in the joints or allows significant water infiltration (ASTM 6433) (3). Jointed plain concrete pavement (JPCP): A concrete pavement system characterized by short joint spacing and no mid-panel reinforcement. Smooth dowels may be placed across the trans- verse joints to facilitate load transfer. (CPTC 2007) (9). Jointed reinforced concrete pavement (JRCP): A concrete pavement system characterized by long joint spacing and containing steel mesh reinforcement distributed throughout the slab to hold any cracks tightly together. Load transfer devices are a common characteristic of this type of design (CPTC 2007) (9). Labor cost: The costs of labor used in performing an activity. Often added to the cost of materials and equipment to result in the total cost of the activity. Linear cracking: Cracks which divide a PCC slab into two or three pieces, usually caused by a combination of repeated traffic loading, thermal gradient curling, and repeated moisture load- ing (ASTM 6433) (3). Also referred to as longitudinal cracking, transverse cracking. Longitudinal and transverse cracking: On asphalt pavements, these cracks are parallel or perpen- dicular 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 (ASTM 6433) (3). Also referred to as longitudinal cracking, transverse cracking, and thermal cracking. Maintenance: Activities that enable a transportation system to continue to perform at its intended level; comprises a range of services in preservation, cleaning, replacing worn or failed compo- nents, periodic or unscheduled repairs and upkeep, motorist services (incident response, hazard- ous materials response), snow and ice control, and servicing of traffic devices and aids; does not add to structural or operational capacity of an existing facility (FHWA) (5). Map cracking and scaling: 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 0.25 in. to 0.5 in. (6 mm to 13 mm) (ASTM 6433) (3). Also referred to as crazing. Material cost: Cost of materials used to perform an activity. Microsurfacing: Mix of crushed, well-graded aggregate, mineral filler, and latex-modified emulsified asphalt spread over entire pavement surface with specialized equipment (ISSA 2010) (ARRA). Partial-depth repairs: Localized removal and replacement of deteriorated concrete (most often in vicinity of joints) in the upper third of the slab using approved repair materials (SHRP 2) (15). Patching: The removal and replacement of a localized area of pavement with new material to repair the existing pavement. A patch is considered a defect no matter how well it is performing (ASTM 6433) (3). 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 condi- tion (ASTM 6433) (3). Pavement distress: Visible indicators of pavement deterioration caused by loading, environ- mental factors, construction deficiencies, or a combination thereof. Pavement distresses are typically further characterized by severity level: low, medium, and high (ASTM 6433) (3).
Glossary 85 Pavement maintenance: Work that is planned and performed on a routine basis to maintain and preserve the condition of the highway system or to respond to specific conditions and events that restore the highway system to an adequate level of service (SHRP 2) (15). Pavement subbase layer: Layer of material in a pavement structure immediately beneath the base course (SHRP 2) (15). Pavement subgrade: The native soil prepared and compacted to support a pavement structure (SHRP 2) (15). Pavement wearing course: The top layer of a pavement structure. Also referred to as pavement surface, surface course, surface layer, wearing course, and weathering course. Polished aggregate: The wearing away of aggregate texture by repeated traffic applications (ASTM 6433) (3). Popout: The loss of a small piece of pavement due to freeze-thaw action. More commonly found with expansive aggregates, chert, clay particles, and other low quality materials (ASTM 6433) (3). Potholes: The loss of the pavement surface in a smallâusually less than 30 in. (750 mm) in diameterâbowl-shaped area of the pavement surface. They generally have sharp edges and vertical sides near the top of the hole (ASTM 6433) (3). 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) (SHRP 2) (15). 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 main- tains or improves the functional condition of the system (without significantly increasing the structural capacity) (FHWA) (13). Pumping: The ejection of material from the slab foundation through joints or cracks. This is caused by deflection of the pavement from passing loads (ASTM 6433) (3). Punchout: In a CRCP, 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 (ASTM 6433) (3). Raveling: Dislodging of coarse aggregate particles in an HMA surface. Raveling may be caused by insufficient asphalt binder, poor mixture quality, insufficient compaction, segregation, or stripping (ASTM 6433) (3). Reactive maintenance: Emergency or other unprogrammed time-sensitive maintenance or repair that arises as a response to observed defects or performance problems (e.g., small bridge deck repairs, traffic signal repairs, incident response) (AASHTO) (1). Retrofitted edge drains: Devices added to a pavement after it is in service to facilitate removal of subsurface water. They usually consist of a drainage feature that is placed between the edge of the pavement and the shoulder. This is a technique used to collect water that has infiltrated into the pavement structure and discharges it to the ditches through regularly spaced outlet drains (CPTC 2008) (10). Roughness: Longitudinal distortions of the road surface that contribute to an undesirable, unsafe, uneconomical, or uncomfortable ride (SHRP 2) (15). Routine maintenance: Work that is planned and performed on a routine basis to maintain and preserve the condition of the highway system or to respond to specific conditions and events that restore the highway system to an adequate level of service (FHWA) (13)
86 Framework for a Pavement-Maintenance Database System Rutting: A depression in the wheel paths of a pavement surface. It is a permanent deformation of one or more layers of the pavement structure (ASTM 6433) (3). Sandblasting: The use of compressed air to blast a surface with an abrasive medium (sand) for quickly preparing the surfacing for repair. Shattered slab: A concrete slab that is divided by cracks into four or more pieces due to overloading, or inadequate support, or both (ASTM 6433) (3). Also referred to as divided slab. Shoving: A permanent, longitudinal displacement of a localized area of an HMA pavement surface caused by traffic loading (ASTM 6433) (3). Shrinkage cracking: Hairline cracks that usually are less than 6.6 ft. (2 m) long and do not extend across the entire concrete slab (ASTM 6433) (3). Slab stabilization/slab jacking: The restoration of support beneath concrete slabs by filling voids, thereby reducing deflections. Slab jacking involves raising slabs to their desired elevation by pressure inserting material beneath settled slabs (CPTC 2008) (10). Slippage cracking: Crescent or half-moon shaped cracks in an HMA surface, usually transverse to the direction of travel. They are produced when braking or turning wheels cause the pavement surface to slide or deform (ASTM 6433) (3). 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 asphalt pavements (ISSA 2010) (ARRA). Spalling: Breakdown of a concrete slab within approximately 1.5 ft. (0.5 m) of a corner, joint, or crack (ASTM 6433) (3). Surface friction: The retarding force developed at the tire-pavement interface that resists sliding when braking forces are applied to the vehicle tires (SHRP 2) (15). Swelling: An upward bulge in the pavementâs surface; a long, gradual wave more than 10 ft. (3 m) (ASTM 6433) (3). Thin bonded wearing course: A bituminous layer placed on top of an existing pavement to improve the functional or surface characteristics of the pavement, including enhancing friction and reducing noise. Consists of open-graded or gap-graded aggregates and rubberized or polymer- modified asphalt layer 0.4 in. to 0.8 in. (10 mm to 20 mm) thick well bonded to the concrete surface (NAPA) (7). Also referred to as ultra-thin bonded overlay and ultra-thin bonded wearing course. Treatment cost: The total cost of applying a maintenance treatment (includes labor, equip- ment, materials, pay items, traffic mobilization, and overhead costs). Ultra-thin and thin HMA overlay: Asphalt binder (may be polymerized) and dense-graded, gap-graded, or open-graded aggregate combined in central mixing placement and placed with paver in thickness ranging from 0.625 in. to 0.75 in. (16 mm to 19 mm) for ultra-thin and 0.75 in. to 1.5 in. (19 mm to 38 mm) for thin overlays. Cost and performance depends on binder type and whether milling is performed prior to treatment placement (NAPA) (7). Ultra-thin whitetopping: A thin, 2 in. to 4 in. (50 mm to 100 mm), PCC overlay of an existing HMA pavement. Ultra-thin whitetopping is a functional overlay that provides a stable surface that is resistant to deformation from static, slow moving, and turning loads (CPTC 2008) (10). Also referred to as thin concrete overlay. Weathering: The wearing away of the asphalt binder and fine aggregate matrix (ASTM 6433) (3).
