Performance mix design (PMD) of asphalt mixtures, often referred to as balanced mix design, is a design methodology that incorporates performance testing into the mix design process. The Virginia Department of Transportation (DOT), like many owner agencies, is interested in ways to specify asphalt mix designs better in an effort to make its roadway network more sustainable, longer lasting, and more economical. By adding performance criteria through a PMD framework, that goal can be achieved. Further, a PMD framework should allow for the development of new, innovative methods to increase pavement recyclability, new performance additives, and other means to enhance pavement performance. This paper provides details and documentation of the approach being taken by the Virginia DOT in their efforts to develop a PMD specification. Aspects of development presented include PMD method options, selection of performance tests, and determination of acceptance criteria. A discussion about validating specifications with in-service performance data and addressing quality control and quality assurance is also provided. Although additional work is needed for full development and implementation, the methodology being applied has been found to provide useful outcomes for the Virginia DOT even in the initial stages of development.
THE CONTACT ANGLE CONTROL OF THE SOLDER FOR IMPROVING THE SOLDERING QUALITY
