Definitions

Alligator Cracks

Interconnected cracks forming a series of small blocks resembling an alligator's skin or chicken wire.


Asphalt Concrete

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


Asphalt Emulsion Slurry Seal

A mixture of slow-setting emulsified asphalt, water, aggregate and mineral filler, produced to a slurry consistency and placed on pavement surface.


Asphalt Fog Seal

A light application of slow-setting asphalt emulsion diluted with water. It is used to renew old asphalt surfaces and to seal small cracks and surface voids.


Asphalt Leveling Course

A layer of an asphalt aggregate mixture of variable thickness used to eliminate irregularities in the contour of an existing surface prior to placement of an overlay.


Asphalt Overlay

One or more courses of asphalt-aggregate mixtures placed on an existing pavement. The overlay generally includes a leveling course and/or pavement milling to correct the contour of the old pavement, followed by uniform course(s) to provide needed thickness.


Asphalt Pavements

Pavements consisting of a surface course of mineral aggregate coated and cemented together with asphalt cement, placed on supporting courses such as asphalt bases; crushed stone, slag, or gravel; or on portland cement concrete, brick, or block pavement.


Asphalt Prime Coat

An application of low-viscosity cutback to an absorbent surface, or a mixed-in application of emulsified asphalt. It is used only on an untreated base prior to placement of the asphalt pavement.


Asphalt Surface Treatments

Applications of asphalt materials to any type of road or pavement surface, with or without a cover of mineral aggregate, that produce an increase in thickness of less than 25 mm (one inch).


Asphalt Tack Coat

A very light application of asphalt applied to an existing asphalt or portland cement concrete surface, used to ensure a bond between the surface being paved and the overlying course. Asphalt emulsion diluted with water is the preferred asphalt material.


Bleeding or Flushing Asphalt

The upward movement of asphalt in an asphalt pavement resulting in the formation of a film of asphalt on the surface.


Blow-Up

The localized buckling or shattering of a rigid type pavement, occurring usually at transverse crack or joint.


Chip Seal

An asphalt emulsion sprayed on existing asphalt or existing surfaces with a washed 3/8 stone applied for a surface treatment for skid resistance and asphalt preservation. Also used for dust control on driveways and secondary roads.


Corrugations (Washboarding)

A form of plastic movement typified by ripples across the pavement surface.


Crack

Separation of the pavement due to natural causes, traffic action, or reflections from an underlying pavement.


Deflection

The downward vertical movement of a pavement surface due to the application of a load to the surface.


Depressions

Localized low areas of limited size that may or may not be accompanied by cracking.


Disintegration

The breaking up of a pavement surface from its original shape.


Fault

A difference in elevation of two slabs at a joint or crack.


Full-Dept Asphalt Pavement

An asphalt pavement structure that uses asphalt mixtures for all courses above the subgrade or improved subgrade. A Full-Depth asphalt pavement is laid directly on the prepared subgrade.


Hot Mix Asphalt

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


Hydroplaning

The dangerous action of a vehicle being driven on a pavement over which a film of rain or other water has formed; on reaching certain speed, the vehicle's tires tend to ride upon the water surface rather than the pavement, drastically reducing the driver's control of the vehicle.


Micro-Surfacing

Micro-Surfacing is a mixture of polymer modified asphalt emulsion, mineral aggregate, mineral filler, water and other additives, properly proportioned, mixed and spread on a paved surface.


Mixed-in-Place (Road-Mix)

An asphalt course produced by mixing mineral aggregate and cutback or emulsified asphalt at the road site using travel plants, motor graders, or special road-mixing equipment.


Plant Mix

A mixture, produced in an asphalt mixing plant, consisting of mineral aggregate uniformly coated with asphalt binder.


Polished Aggregate

Aggregate particles in a pavement surface with edges that have been rounded and surfaces polished smooth by traffic.


Potholes

Bowl-shaped holes of varying sizes in the pavement, resulting from localized disintegration.


Pumping

Slab movement under passing loads resulting in the ejection of mixtures of water, sand, clay, and/or silt along transverse or longitudinal joints and cracks, and along pavement edges.


Raveling

The progressive separation of aggregate particles in a pavement from the surface downward or from the edges inward.


Recycling

The re-use, usually after some reprocessing, of a material that has already served its first intended purpose.


Reflection Cracks

Cracks in asphalt overlays that reflect the crack pattern in the pavement structure underneath.


Rutting

Channelized depressions that may develop in the wheel tracks of an asphalt pavement.


Scaling

The peeling away or disintegrating of the surface of portland cement concrete.


Seal Coat

A thin asphalt surface treatment used to waterproof and improve the texture of an asphalt wearing surface. Depending on the purpose, seal coats may or may not be covered with aggregate. The main types of seal coats are fog seals, aggregate seals, slurry seals, and sand seals.


Shoving

A form of plastic movement resulting in localized bulging of the pavement.


Skid Hazard

Any condition that might contribute to making a pavement slippery.


Slippage Cracks

Cracks, sometimes crescent-shaped, that point in the direction of the thrust of the wheels on the pavement surface, caused by lack of bond between two pavement layers.


Spalling

The breaking or chipping of pavement at joints, cracks, or edges, usually resulting in fragments with feather edges.


Undersealing Asphalt

A high softening point asphalt used to fill cavities beneath portland cement concrete slabs and occasionally to correct the vertical alignment by raising individual slabs.


Upheaval

The localized upward displacement of a pavement due to swelling of the subgrade or some portion of the pavement structure.