The useful life and maintenance cost of these roads often is affected by the quality of the asphalt, an extremely complex mixture with a highly variable composition that depends on the crude oil from which it is derived. In spite of the importance of having high asphalt quality, asphalt generally is much more variable than other products produced by the refining and petrochemical industry because of changing crude supplies, a general lack of knowledge of the relationships between asphalt composition and performance, and uncertainty, historically, over what constitutes good performance properties. The Center for Asphalt and Materials Chemistry seeks to develop the knowledge to produce high-performing asphalt materials at reasonable cost. An industrial advisory committee comprised of individuals from several companies having a major interest in asphalt production assists the Center which maintains close contact with the Texas Department of Transportation which is responsible for highway construction, maintenance and research in the state. Funding for the Center comes from federal, state, and private sources.
Applications are primarily to pavements but also include roofing materials.
An asphalt cannot be evaluated with respect to long-term performance until it has been aged in a manner comparable to normal road aging where the asphalt has not been newly laid and is failing. Center researchers have shown that no accelerated aging simulation at a single elevated temperature can accurately predict the rate of aging at road temperatures, so they have developed a test which measures relative rates of aging at varying road temperatures. The hardening of each asphalt has been shown to be a function of the infrared spectrum of the material and has been related to the growth of hydrocarbon insoluble material. A property which characterizes the extent to which oxidation hardens asphalt has been identified by Center researchers and is termed the hardening susceptibility. This property, in addition to the Superpave properties, is being investigated for its role in pavement performance and binder design.