Development and Application of a Statistical Quality Assessment Method for Dense-Graded Mixes

摘要

This report describes the development of the statistical quality assessment method and the procedure for mapping the measures obtained from the quality assessment method to a composite pay factor. The application to dense-graded mixes is demonstrated with an example. This report also describes the development of a smoothness specification based on the IRI. A draft smoothness specification is also included in the appendices. The research team developed a methodology to measure the quality of dense-graded asphalt mixes based on a statistical function called a loss function. Various formulations of the loss function are routinely used in manufacturing to provide quality control/quality assurance measures. The methodology developed for this project provides a pay incentive to contractors that exceed quality expectations, and a penalty to those who fall short of quality expectations. The methodology encourages contractors to produce asphalt mixes that are consistent with specifications with minimum variability. Two principal specification-related products were produced. The first product allows ODOT to statistically judge the HMA quality using the loss function. Second, data analyses showed that project smoothness, as measured by IRI, could be incorporated into an ODOT specification, but only in the form of percent improvement in ride over the existing roadway.