A.D.A. The Americans with Disabilities Act
This comprehensive federal act was passed to ensure uniform compliance with standards for the benefit of those with disabilities. It’s scope encompasses everything from the width of doorways and force required to open them to the use of Braille in elevators to assist the visually impaired. Most common in relation to pavement are the standards for disabled parking, access aisles, curb ramps, signage and markings etc. Some states and municipalities also have laws which regulate proper accessibility for the disabled.

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 %.)

The common name for “Bituminous Asphalt 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 minimum depth of 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.

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 and may vary from 3-4″ for a residential driveway to 18″ or more for parking areas or roadways. 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.

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).