Impact of asphalt mixture design parameters on transverse cracking performance and laboratory testing results

Abstract

In cold climate regions, thermal cracking of asphalt pavements is a primary pavement distress. Cold climates cause thermal contraction within the pavement. When combined with the brittle behavior of asphalt at low temperatures, the thermally induced stresses are relieved by transverse cracks forming in the pavement. This cracking facilitates poor ride quality and premature failure of the pavement. There is currently no asphalt mixture performance test required by a majority of Department of Transportations (DOTs) in the United States to address the issue of thermal cracking. Previous research has indicated that fracture energy of asphalt mixtures is a reliable predictor of transverse cracking performance. This mechanistic property of asphalt mixtures can be found using the disk-shaped compact tension (DCT) test. On basis of previous research, a low-temperature cracking performance specification that uses DCT fracture energy has been developed. This project focused on eighteen highways containing twenty-six separate study sections. The projects encompassed different construction techniques, material compositions and climatic zones. The results from field studies, analysis of the mix parameters for each section and laboratory testing for sections are presented in this document. The results provide validation for previous research that suggests the use a performance test is vital to accurate projection of roadway transverse cracking performance. Other findings include reaffirmation of common knowledge about various mix parameters that suggest increasing or decreasing values will have positive and negative effects on both cracking amounts and performance testing. In nearly all instances, sections with an overlay construction type performed inferior to reclaimed construction types. For example, reclaimed sections exhibited roughly one-third the average transverse cracking amount of overlay sections. This phenomenon will be monitored in future studies.