Glossary
ASPHALTIC CONCRETE (AC): Plant mixed asphaltic concrete, well graded, crushed aggregate with a smooth surface texture.
CEMENT TREATED BASE (CTB): A structural base layer consisting of aggregate bound or cemented by portland cement.
CHIP SEALS: A mixture of aggregates and asphalt cements applied as an aggregate seal coat. The asphalt cement is sprayed on the pavement and then aggregates are sprinkled on the surface.
COAL TAR SEAL: An emulsified non-asphaltic byproduct of the coal coking process that is sometimes used as surface seal. It is incompatible with asphaltic concrete materials and usually has a clay extender added, which makes this product subject to extensive shrinkage cracking. NOT RECOMMENDED unless mandatory for gas spillage resistance.
DIGOUTS: Localized pavement repairs to correct structural deficiencies. The pavement is saw-cut in rectangular patterns and all material within the rectangle is removed and replaced.
FABRIC: In pavement terminology, a reference to fabrics is to refer to a crack retardant fabric membrane placed on the existing surface of an existing pavement under a new overlay or a soil stabilization fabric (geotextile) placed over unsuitable soils.
FILLED ASPHALT EMULSION: Usually a soft-based
SSI-H asphalt emulsion containing ungraded fillers (such as clay, slate, polyethylene fibers, celluloid and/or asbestos).
FILLED ASPHALT SEALERS: A full range of emulsified asphalt surface seals, usually consisting of softer grade asphalts, such as 551- H and fillers like clay, slate, polyethylene fibers, sands, etc.
FOG SEAL: A spray applied emulsified asphalt seal that is used as a seasonal winterizer to protect asphaltic cements. Usually consisting of a soft based 551-H lasting only one season.
FULL DEPTH ASPHALT: A design methodology where the asphalt concrete material provides the majority of the pavement structural support.
INTERLAYER: Any material placed on the surface of an existing pavement and “sandwiched” under a new pavement layer.
OVERLAY: The placement of asphaltic concrete mix over an existing asphaltic concrete or portland cement concrete surface.
PORTLAND CEMENT CONCRETE (PUC): Aggregate with cement binder, characterized by the gray/white color. Relatively smooth, uniform concrete surface having few exposed aggregates.
PRIME COAT: A spray applied asphalt product used on the surface of new aggregate base to promote bonding between the asphalt surfacing and aggregate base layers.
REFLECTION CRACKING: The phenomenon that occurs to create cracks in new thin overlays that are identical to cracks that were present in existing pavement.
SEAL COATS: Seal coats or maintenance seals are generic terms for any of a number of surface coatings, such as coal tar, filled asphaltic sealers, Gilsonite seals, etc. All are aimed at protecting against moisture intrusion and raveling.
SLURRY SEALS: Slurry seals differ from other seal coats in that they include a graded aggregate along with the emulsion and water. They are squeegee applied and generally consist of one of four types:
- Type 0: A low penetration asphaltic surfacing that contains a chemically suspended fine graded aggregate (usually 10% passing the No. 16 mesh size).
- Type I: An emulsified asphalt, water and aggregate mixture with graded aggregates of No. 8 maximum size added at the job site.
- Type II: An emulsified asphalt, water and aggregate of No. 4 maximum size with aggregates added at the job site. Type II is commonly referred to as “highway slurry seal.”
- Type III: An emulsified asphalt, water and aggregate of 3/8 inch maximum size with aggregate added at the job site. Type III is not commonly used for anything but major highways and rural roadways.
STRATEGY: In pavement maintenance, this is a term used to reference any maintenance/rehabilitation or reconstruction action taken to preserve, protect, or replace the pavement investment.
TACK COAT: A spray applied asphalt product used to promote bonding between new asphalt concrete and other surfaces. Most commonly used between asphalt concrete pavement layers.
