Paving Glossary
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Paving Glossary
Here is a list of commonly used asphalt terms:
Asphalt
Originally a naturally occurring product in use for centuries, the early 1900s brought today’s refined petroleum product. This term is often applied to almost any asphalt product from H.M.A.C. to asphalt cements and oils.
Asphalt Cement
A dark brown to black cementation material in which the predominating constituents are bitumens which occur in nature or are obtained in petroleum processing. In varying proportions, asphalt is a constituent of most crude petroleums.
Base
Generic term for material installed prior to asphalt paving. May be a crushed stone product or asphalt product. The base material provides the load-bearing characteristics of the finished pavement and may vary from 3–4″ for a residential driveway to 18″ or more for parking areas or roadways. Lack of adequate base material is a primary cause of pavement failures.
Blacktop
Common slang term for asphalt. However, this term should not be used in requesting any specifications or work as the term is widely used with various meanings in different areas.
Course, Asphalt Base
A foundation course consisting of mineral aggregate, bound together with asphalt material.
Course, Asphalt Surface
The top course of an asphalt pavement, sometimes called asphalt wearing course.
Crack Filler
A material that is placed in a pavement crack or joint to fill but not necessarily seal the void created by the crack or joint.
Crack Sealant
A material that has adhesive and cohesive properties to seal cracks, joints or other narrow openings (less than 1½” wide) in pavements against the entrance or passage of water or debris.
Emulsion
Mechanically produced combination of ingredients which do not normally mix. Asphalt emulsions are made by mechanically milling warm asphalt into minute globules, dispersing them in water, and adding an emulsifying agent.
Fog Seal
A process of applying a highly diluted asphalt emulsion in a fine spray (fog) to a roadway surface. Restores blackness and seals hairline cracks; may prevent or slow oxidation. Not generally used for parking facilities due to tracking.
Full-Depth Asphalt Pavement
The process of constructing an asphalt pavement structure using asphalt products for all components. The base material and surface courses are made up of appropriately specified grades of hot-mix asphalt. Numerous benefits exist to this method of construction.
H.M.A.C. (Hot Mix Asphalt Concrete)
Proper name for what is commonly referred to as “asphalt” or “blacktop.” This term should be used in specifying asphalt work. H.M.A.C. is produced in many grades from coarse base mixes to specialized surface and repair mixes.
Laydown
The portion of the asphalt paving process where the hot asphalt is placed or “laid down” by the paving machine.
Mat, Asphalt
A term used to describe the fresh asphalt surface behind the paving machine, primarily during laydown and compaction.
Paving Machine (Paver)
The equipment used to place asphalt or concrete materials in their finished position. In asphalt construction, these machines must place a smooth finish at the proper depth and provide initial compaction.
Prime Coat
A coating of asphalt oil (cutback or emulsion) used to seal the sub-base or base material and enhance bonding to the asphalt course.
Reflective Cracking
Cracks in an asphalt overlay caused by cracks in the existing pavement reflecting upward. Specialized techniques and materials can reduce this problem.
Routing
Enlargement of pavement cracks using a specialized machine to create a uniform reservoir for sealant. When done properly, this increases the durability of crack sealing.
Sealcoating
Application of a sealant (coal-tar or asphalt emulsion) to preserve, protect, and beautify asphalt surfaces. Commercial sealcoating products are mixed with water, sand, and additives in exact ratios.
Slurry Seal
A sealcoating process used mainly on runways, streets, and roadways. The coating is mixed during application and includes asphalt emulsion, additives, and aggregate. Types I–III are based on aggregate size.
Subgrade
The soil prepared to support a pavement system; the foundation for the pavement structure.
Tack Coat
Asphalt oil, usually an emulsion, applied to existing pavement during repairs or overlays to create a bond between old and new asphalt.