HMA segregation occurs throughout the United States, and numerous studies have been conducted to identify its causes. However, little has been done to systematically develop definitions of segregation or to develop procedures to detect segregation and evaluate the effect of segregation on HMA pavement properties and performance. Because most identification methods are subjective visual interpretations of the HMA pavement surface appearance, many disagreements occur among contracting parties that could be resolved if there were established procedures for identifying, measuring, and evaluating the effects of segregation.

The objective of this research was to develop procedures for defining, locating, and measuring segregation and to evaluate segregation's effects on HMA pavement performance.

The project developed recommended methods and specifications to detect and measure segregation of hot-mix asphalt (HMA) using infrared thermography or ROSANv laser surface texture measurements. The final report was published as NCHRP Report 441, "Segregation in Hot-Mix Asphalt Pavements," and is also available in its entirety on NCHRP CD-ROM CRP-CD-8, "Bituminous Materials Research Series II, NCHRP Projects 9-11, 9-12, and 9-13." The recommended test methods were referred to the AASHTO Highway Subcommittee on Materials.