ASPHALT PAVING GLOSSARY Next Page >
Aggregates: Usually various sized stones, crushed rock, gravel, etc. that make up approximately 92-96% of the asphalt mixture. (Asphalt Cement makes up the other 4-8 %.)
Asphalt: The common name for "Bituminous Concrete". It is also known as "flexible pavement." It is a mixture of aggregates and hot asphalt cement that when placed, compacted and subsequently cooled, becomes the familiar asphalt.
Asphalt Base: Asphalt mix where the largest stone used is no larger than 3/4 of an inch ( typically #57 gradation). Base mixes are usually laid over a stone base at a depth of 1 1/2 to 2 inches compacted.
Asphalt Binder: The asphalt layer between the base layer of rock or other aggregate and the driving surface layer. The asphalt binder layer is usually made up of coarser materials and is usually thicker than the surface layer. The binder layer can be used as either a first layer or a driving surface, but its use is actually fairly limited. The vast majority of jobs call for a stone base layer, an asphalt base layer, then a surface layer.
Asphalt Cement: A petroleum byproduct used to "glue" the pavement together. By volume, this material makes up about 4-8% of the pavement mixture. (Aggregates make up the other 92-96%).
Asphalt Concrete: See definition of "Asphalt" above.
Base: Generic term for material installed prior to asphalt paving. May be a crushed stone product or asphalt product (see full-depth asphalt pavements). The base material provides the load bearing characteristics of the finished pavement. The correct type and amount of base material must be determined and specified prior to paving. Lack of adequate base material is a primary cause of pavement failures.
Base Failure: Base failures occur when the layer beneath the binder layer and driving surface can no longer adequately support the weight of the structure or the traffic. Base failures can occur for a number of reasons, including: ground water, excessive load counts (too much weight), and inadequate design. The failure can be corrected by excavating the failed material and replacing it with bridging stone material.
BCBC: BCBC is made by using 1 1/2 inch stone. It has a very pores finish which allows water to penetrate into the sub-base. BCBC is very strong and makes a great base, but should have a ID-2 wearing coarse applied as well.
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. For example sometimes "blacktop" is used to refer to a penetration pavement or hot oil treatment (see fog seal).
Coal-Tar: A by-product of coke ovens in the steel production industry. Refined coal-tar has been used as a base for asphalt pavement sealers since 1938. It has become more expensive in recent years due to the shift in steel production to foreign countries.
Compaction: Compressing a given volume of material into a lesser volume. A compacted subgrade and base is essential.
Concrete: A hard, compact building material formed when a mixture of cement, sand, gravel, and water dries.
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.
Cracking: A separation of the asphalt layer due to excessive loads (weights), heat, or age.
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