AASHTO: American Association of State Highway Transportation Officials.  This organization sets standards and publishes specifications, test protocols and guidelines which are used in highway design and construction throughout the United States.

Absolute Viscosity: A measure of the viscosity of asphalt with respect to time, measured in poises, conducted at 60°C (140°F). The test method utilizes a partial vacuum to induce flow in the viscometer.

ADA: Americans with Disabilities Act.  With regard to pavement, the Act provides regulations governing accessibility related to parking, ramps, etc. and accessible paths of travel for the disabled community.

Alligator Cracks:Interconnected cracks forming a series of small blocks resembling an alligator’s skin or chicken-wire, and caused by excessive deflection of the surface over unstable subgrade or lower courses of the pavement.

API gravity:  A function of specific gravity represented by the equation in Test Method D3142/D3142M.

ASTM: American Society of Testing and Materials.This organization develops uniform methods and standards for product quality.

Back-calculation: An analytical technique used to determine the equivalent elastic moduli of pavement layers corresponding to the measured load and deflections. In the iterative method, layer moduli are selected and adjusted until the difference between the calculated and measured deflections are within selected tolerances, or the maximum number of iterations has been reached.

Balanced Paving Operation: The synchronized balance of the four phases of asphalt paving to provide continuous paving operations. The four phases are mixture production, mixture hauling, paving operations, and compaction.

Base Course: The layer of material immediately beneath the surface or intermediate course. It may be composed of crushed stone, crushed slag, crushed or uncrushed gravel and sand, or of hot mix asphalt, typically with larger size aggregate.

Blacktop: A generic term for asphalt concrete.

Bleeding or Flushing: The upward movement of asphalt in an asphalt pavement resulting in the formation of a film of asphalt on the surface. The most common cause is too much asphalt in one or more of the pavement courses, resulting from too rich a plant mix, an improperly constructed seal coat, too heavy a prime or tack coat, or solvent carrying asphalt to the surface. Bleeding or flushing usually occurs in hot weather.

Block Cracking: A combination of longitudinal and transverse cracking in asphalt concrete that generally results as the binding agent evaporates and the asphalt hardens and shrinks.  It has a distinctive checkerboard pattern.

Bulk Density: the ratio of the mass of a material to the volume it occupies.

Bulk Specific Gravity: The ratio of the mass of a given volume of material, including the impermeable and permeable voids, to the mass of an equal volume of water at a specified temperature.

California Bearing Ratio (CBR): A test used for evaluating bases, subbases, and subgrades for pavement thickness design it is a relative measure of the shear resistance of a soil (see Soils Manual, MS-10). CBR = load required to force a calibrated piston into a soil specimen / load required to force a like piston into a crushed stone specimencapacity and ride quality of the pavement system.

Cape Seal: A surface treatment where a chip seal is followed by the application of either slurry seal or micro surfacing.

Cessation Temperature: The unique temperature for an asphalt mixture below which additional densification is more difficult and continued attempts may damage to the mat, typically around 175-180˚F (80-82˚C) for typical hot mix asphalt applications. Cessation temperatures many be lower for warm mix asphalt applications.

Channels (Ruts): Channeled depressions that sometimes develop in the wheel paths of an asphalt pavement.

Chip seal: a two-step process that combines a layer of aggregate followed by a high viscosity emulsion seal coat.  Used primarily on low-volume roads, it covers surface imperfections, improves surface friction and adds a new wear surface.

Cold In-place Recycling Train: A unit consisting of a large milling machine towing a screening/crushing plant and pugmill mixer for the addition of asphalt emulsion and production of cold mix base.

Compaction: The act of compressing a given volume of material into a smaller volume. Insufficient compaction of the asphalt pavement courses may accelerate the onset of pavement distresses of various types.

Crack Filler: Bituminous material used to fill and seal cracks in existing pavements.

Crack seal: An inexpensive emulsion of hot rubberized asphalt used to seal longitudinal, transverse and block cracking to prevent water from seeping beneath the asphalt to the subgrade where structural damage occurs.  It also seals against abrasive dirt and sand.

Digout: A localized repair or patch that involves digging out or excavating an area of damaged pavement, such as a pothole, and replacing it with new asphalt concrete. It is designed to prevent damage to the subgrade.

ESAL: Equivalent Single Axle Load. One ESAL is equal to one 18,000-pound axle. An ESAL determines the impact of heavy wheel loads that are quantified as a Traffic Index, which helps determine how much loading a pavement will support before it begins to fail.

Fatigue: Pavement deterioration caused by repetitive heavy wheel loads that results in cracking from the bottom of the pavement structure upward.  It usually appears as alligator cracking.

Flexible pavement: A structural section of road made up of asphalt concrete and one or more layers of aggregate that is designed to distribute loading to the underlying subgrade.  If properly designed, flexible pavement can expand or stretch to absorb heavy loads.

Full-depth asphalt: A pavement structure using hot mix asphalt (HMA) for both the base and surface materials.

Laydown: The portion of a paving process where HMA is placed or “laid down” by a paving machine.

Lime treatment: A modifier for or additive to soil subgrade that increases its R-value, improves performance and adds years to pavement life.

Longitudinal cracking: Cracks in asphalt concrete pavement that run parallel to the pavement’s centerline or laydown direction. It results primarily from environmental aging.

Maintenance: Regularly timed pavement preservation treatments necessary for safety and to extend service life, typically for up to five years.  Maintenance treatments can include crack sealing, seal coats, slurry seals, chip seals and overlays or any combination of these and other treatments.

Maintenance Mix: A mixture of bituminous material and mineral aggregate applied at ambient temperature for use in patching holes, depressions, and distress areas in existing pavements using appropriate hand or mechanical methods in placing and compacting the mix. These mixes may be designed for immediate use or for use out of a stockpile at a later time without further processing.

Milling: The controlled removal an existing asphalt pavement layer to correct and restore the surface to a specified profile.

Mill and fill: A pavement rehabilitation process that involves milling (removing) the surface layer of pavement to a predetermined depth and filling it with new or recycled HMA.  It creates a smooth ride by eliminating tire ruts and other defects.

MTC:  Metropolitan Transportation Commission. MTC is the regional planning organization for roads and transit in the San Francisco Bay Area.

Native subgrade: The base or soil upon which the pavement structure is built. It can be augmented by structural fill material.

OGFC: Open Graded Friction Course.  OGFC is a non structural wear course used primarily on HMA to improve wet weather skid resistance, reduce the potential for hydroplaning, reduce water splash and spray and reduce night time wet pavement glare. 

Overlay: A pavement rehabilitation process for severely deteriorated pavement that overlays bituminous asphalt concrete on top of existing pavement to strengthen its overall structure, improve ride and extend service life.

Pavement: The surface layer of a structural section of road that carries traffic.  It is composed either of asphalt concrete or Portland cement concrete. 

Pavement Management System (PMS): A system developed by Caltrans to assess the condition of pavement biennially and prioritize pavement maintenance and rehabilitation consistent with available funding.

Penetration: The consistency of a bituminous material expressed as the distance in tenths of a millimetre (0.1 mm) that a standard needle penetrates vertically a sample of the material under specified conditions of loading, time, and temperature.

Potholes: Bowl-shaped holes caused by water damage that may extend into the base.

Profilograph: A device used to measure pavement surface roughness.  The data collected by a profilograph is used to calculate the International Roughness Index (IRI), which is expressed in units of inches/mile or millimeters/meter. IRI values range from 0 (equivalent to driving on a plate of glass) upwards to several hundred (a very rough road). The IRI value is used for road management to monitor road safety and quality issues.

Pulverization: A mechanized process that transforms the existing flexible pavement surface layer and a portion of the underlying granular layer into a uniform granular material suitable for use as a base layer. 

R-value: Resistance Value. R-value is a measure of resistance to deformation under loading of saturated soil. 

Raveling: Also called weathering, raveling is the progressive and gradual deterioration of the HMA layer. It results as the asphalt concrete binder oxidizes, separating it from the coarser aggregates and making the surface rough and uneven.

Reconstruction: Replacing an existing pavement structure that has reached the end of its service life or is badly deteriorated with a new, equivalent pavement structure that may use new or recycled paving materials or a combination of both.

Reflection cracking: Cracks that generally occur on pavements where an asphalt concrete surface is placed over jointed Portland cement concrete.  Reflective cracking occurs directly over underlying cracks or joints but also can occur over existing HMA pavement cracks, cement or lime stabilized base, etc. 

Rehabilitation: A process that extends the service life of existing pavement by placing additional surfacing (overlay) or other treatment to restore an existing roadway to structural or functional adequacy for a minimum of 10 years.  Rehabilitation may include partial or complete removal and replacement of portions of the structural section.

Rejuvenation: An emulsion similar to a fog seal applied to an oxidized (weathered) pavement to restore flexibility to an existing HMA pavement surface.  The emulsion may include asphalt, polymer latex and other additives. 

RHMA – Rubberized Hot Mix Asphalt: RHMA is a type of asphalt that combines granulated (crumb) rubber with hot asphalt to form an elastic binder with less susceptibility to temperature changes. RHMA is generally specified to retard reflection cracking, resist thermal stresses created by wide temperature variations and add flexibility to a structural overlay.

Rutting: Longitudinal surface depressions in the wheel path of a pavement often caused by an inadequate structural foundation.

Seal Coat: A mix of approximately 85% emulsion and 15% aggregate used to seal rough or raveled pavement in areas with traffic speeds less than 15 mph. A seal coat fills in minor cracks and provides a smooth finish that protects against the environment.

Service life: The approximate lifespan of newly constructed pavement before major rehabilitation or reconstruction is required.  Because of traffic, climate and other variables, service life may be considerably shorter or longer than that for which is was designed. 

Slurry coat: A mix of approximately 15% emulsion and 85% aggregate used to seal rough or raveled pavement in areas with traffic speeds greater than 15 mph. A slurry seal fills in cracks and provides a smooth finish that protects against the environment. It has roughly twice the lifespan of a seal coat. 

Structural section: The designed layers of materials placed over native subgrade to support estimated traffic loads over a specified period of time.  Generally, the structural section normally consists of a subbase, base and pavement surface. 

Subbase: A layer of aggregate designed in thickness and quality placed on top of the native soil or subgrade that serves as a foundation for the base layer.

Subgrade: The native soil or portion of the roadbed on which a pavement surface, subbase, base or layer of other material is placed.

Surface Treatment: An application of bituminous material followed by a layer of mineral aggregate. Multiple applications of bituminous material and mineral aggregate may be used.

Traffic Index (TI): Determines how much loading a pavement will support before it begins to fail.  It is a measure of the number of Equivalent Single Axle Loads (ESALs) expected in the traffic lane over the pavement design life. One ESAL is equivalent to one 18,000-pound axle.

Transverse cracking: Cracks in asphalt concrete pavement that run at right angles to the pavement’s centerline or laydown direction. It results primarily from environmental aging.

Washboard: Also called corrugations, the regularly spaced rough transverse “bumps” caused by an unstable surface course. 

Weathering: Also called raveling, weathering is the progressive and gradual deterioration of the HMA layer. It results as the asphalt concrete binder oxidizes, separating it from the coarser aggregates and making the surface rough and uneven.

PCC: Portland Cement Concrete. PCC is rigid and more durable than flexible asphalt pavement, and as such, is a pavement alternative for areas affected by heavy wheel loads from buses, garbage trucks and service vehicles

Rigid pavement: A structural section of road constructed of rigid Portland cement concrete that is designed to distribute axle loads over a relatively wide area.

Aggregate: A granular material used as a construction material, meeting the requirements of road and paving applications.

Aggregate Spreaders: Machines used for spreading aggregate evenly at a uniform rate on a surface.

Aggregate Storage Bins: Bins that store the necessary aggregate sizes and feed them to the dryer in substantially the same proportions as are required in the finished mix.

Aggregate Trucks: Trucks equipped with hydraulic lifts to dump the aggregate into the spreader or storage area.

Aggregate Types:

• Coarse Aggregate: Aggregate particles retained on the 2. 36 mm (No. 8) sieve.
• Fine Aggregate:  Aggregate particles passing the 2. 36 mm (No. 8) sieve and retained on the 0. 075 mm (No. 200) sieve.
• Mineral Filler: A finely divided mineral product with a maximum of 3 percent retained on the 0. 800 mm (No. 30) sieve and at least 70 percent of which will pass a 0. 075 mm (No. 200) sieve. The most common mineral fillers include pulverized limestone, other stone dust, hydrated lime, Portland cement, fly ash, and certain natural deposits of finely divided mineral matter.

Aggregate Gradation: The particle size distribution from the largest through finest materials.

Aggregate Gradation Types:

• Coarse-Graded Aggregate:A gradation having a continuous grading in sizes of particles from coarse through fine with more material larger than the primary control sieve.
• Dense-Graded Aggregate: A gradation that has a particle size distribution such that when it is compacted, the resulting voids between the aggregate particles, expressed as a percentage of the total space occupied by the material, are relatively small.
• Fine-Graded Aggregate: A gradation having a continuous grading in sizes of particles from coarse through fine with more material smaller than the primary control sieve.
• Gap-Graded Aggregate: A gradation consisting of larger and finer particles but little or no particles in the middle of the gradation band creating a “gap”. Stone Matrix Asphalt (SMA) is a common example of a gap-graded asphalt pavement.
• Open-Graded Aggregate: A gradation containing little or no mineral filler and in which the void space in the compacted aggregate are relatively large, usually 10% or more.
• Well-Graded Aggregate: A gradation with relatively uniform proportions from the maximum size down to filler with the object of obtaining an asphalt mix with a controlled void content and high stability. Well-graded aggregate is also known as uniformly-graded aggregate.

Air Voids: The volume of air between the asphaltcoated aggregate particles throughout a compacted asphalt mix, expressed as a percent of the total volume of the sample.

Automatic Dryer Control: A system that automatically maintains the temperature of aggregates discharged from the dryer within a preset range.

Automatic Proportioning Control: A system in which proportions of the aggregate and asphalt fractions are controlled by means of gates or valves, which are opened and closed by means of self acting mechanical or electronic machinery without any intermediate manual control.

Bank Gravel: Gravel found in natural deposits, usually more or less intermixed with fine material, such as sand or clay, or combinations thereof; gravelly clay, gravelly sand, clayey gravel, and sandy gravel indicate the varying proportions of the materials in the mixture.

Blast-furnace Flag: The nonmetallic product, consisting essentially of silicates and alumino-silicates of calcium and other bases, that is developed in a molten condition simultaneously with iron in a blast furnace.

Crusher-Run: The total unscreened product of a stone crusher.

Fractured Face: An angular, rough, or broken surface of an aggregate particle created by crushing, by other artificial means, or by nature.

Maximum Size (of aggregate): In specifications for, or descriptions of aggregate, the smallest sieve opening through which the entire amount of aggregate is required to pass.

Mineral Filler: Finely divided mineral matter such as rock dust, slag dust, hydrated lime, hydraulic cement, fly ash  loess, or other material predominantly passing the 75-µm
(No. 200) sieve.

Nominal Maximum Size (of Aggregate):In specifications for, or descriptions of aggregate, the smallest sieve opening through which the entire amount of the aggregate is permitted to pass.

Rubble: Rough stones of irregular shapes and sizes, broken from larger masses either naturally or artificially, as by geological action, in quarrying, or in stone cutting or blasting.

Soil Aggregate: Natural or prepared mixtures consisting predominantly of stone, gravel, or sand which contain a significant amount of minus 75-µm (No. 200) silt-clay material.

Steel Slag: The nonmetallic product consisting essentially of calcium silicates and ferrites combined with fused oxides of iron, aluminum, manganese, calcium and magnesium, that is developed simultaneously with steel in basic oxygen, electric, or open hearth furnaces.

Stone Chips: Small angular fragments of stone containing no dust.

Voids in Mineral Aggregate (VMA): Volume of intergranular void space between the aggregate particles of a compacted paving mixture.

Constant Mass: این اصطلاح زمانی به کار می رود که اختلاف در جرم یک نمونه در دو نوبت متوالی اندازه گیری وزن، تحت شرایط بارگذاری معین، ناچیز و قابل چشم پوشی باشد. 

Core test: ضخامت لایه روسازی موجود را برای تعیین ظرفیت سازه ای برای بازسازی راه یا ضخامت لایه بستر برای ساخت راه جدید را  اندازه گیری میکند. این تست هسته گیری( مغزه گیری/ نمونه گیری) از لایه های متفاوت روسازی برای تعیین ساختار، ویژگی های خاک محل و حجم رطوبت را در بر میگیرد. به داده های این تست R-value به معنی مقدار مقاومت گفته می شود. این داده ها عمق مورد نیاز خاک بستر برای تامین نیروی تکیه گاهی برای اساس سنگدانه ای ولایه رویه بتن آسفالتی که میزان مورد انتظار ترافیک و بار چرخ را تحمل خواهد کرد، تعیین می کند.

Deflection test: یک متد آزمایشی غیرمخرب برای تعیین ظرفیت کلی سازه ای و ویژگی های روسازی موجود است. این آزمایش مدول برجهندگی لایه های خاک بستر، اساس و رویه را اندازه گرفته، میزان انعطاف پذیری سازه روسازی را تعیین میکند و تاثیرات ترافیک و

Deflection test: یک متد آزمایشی غیرمخرب برای تعیین ظرفیت کلی سازه ای و ویژگی های روسازی موجود است. این آزمایش مدول برجهندگی لایه های خاک بستر، اساس و رویه را اندازه گرفته، میزان انعطاف پذیری سازه روسازی را تعیین میکند و تاثیرات ترافیک و

Lab Mixed Lab Compacted  Asphalt Mixture Specimen (LMLC): نمونه مخلوط آسفالتی که در آزمایشگاه با وزن کردن و مخلوط کردن هر جزء سازنده آن آماده شده و سپس توسط دستگاه تراکم، متراکم می گردد.

Mesh – مش: چشمه های مربعی شکل الک  

Normal Temperature – دمای نرمال:دمایی که در آن مشاهدات آزمایشگاهی خواص فیزیکی مواد قیری صورت می گیرد. (25 درجه سانتی گراد یا 77 درجه فارنهایت)

Nuclear Gauge:دمایی که در آن مشاهدات آزمایشگاهی خواص فیزیکی مواد قیری صورت می گیرد. (25 درجه سانتی گراد یا 77 درجه فارنهایت)

Screen:وسیله ای با روزنه های دایره ای که  برای جدا کردن اندازه های مختلف مصالح در آزمایشگاه به کار می رود.

Screenings: محصول باقیمانده از خرد کردن مصنوعی سنگ، قلوه سنگ، پاره سنگ، شن، سرباره کوره بلند یا بتن سیمانی هیدرولیکی، که تمام آن از کوچکترین چشمه الک استفاده شده در عملیات شکست سنگ عبور کرده و فقط بخشی از آن از الک 36/2 میلی متر (الک شماره 8) عبور می کند.

 Sieve – الک: وسیله ای که دارای روزنه های مربعی است و برای جدا کردن اندازه های مختلفی از مصالح در آزمایشگاه به کار می رود.

Plant Mixed Lab Compacted (PMLC): نمونه های مخلوط آسفالتی که در کارخانه ساخته شده و قبل از تراکم نمونه برداری می شود و سپس مخلوط بلافاصله با استفاده از دستگاه تراکم آزمایشگاهی متراکم می شود.

Chemical modification of asphalt – آسفالت اصلاح شده شیمیایی: اصلاح شیمیایی مخلوط آسفالتی که می‌تواند با افزودنی پلی فسفریک اسید (PPA) انجام شود.