Cracking Performance of Lower Asphalt Binder Coarse Hot Mix Asphalt Mixes

Abstract

Historically, asphalt mixtures in Minnesota have been produced to be fine-graded in nature. Recently, there are increasingly more coarse-graded mixtures being produced with relatively low asphalt binder content as compared to fine-graded mixtures. The performance of the coarser low asphalt content mixes is not known; therefore, the objective of this study is to determine if the coarse asphalt mixes with lower binder content are prone to a reduced service life and increased performance problems. The present study focused on 13 low asphalt binder content, coarse-gradation mixes from actual field projects constructed mostly in the last 1–5 years. The performance of the pavement sections was quantified using Minnesota Department of Transportation’s (MnDOT) pavement management systems (PMS). Field cracking performance was compared to laboratory tests on core samples procured from the field sections. The field procured core samples were tested using the disk-shaped compact tension (DCT) fracture energy test and permeability measurements. The lab results were also analyzed with each pavement section’s field performance. The results from the study will not only provide answers to this question but also provide estimates of the pavement performances for low binder content mixes. Final outcomes will help revise future asphalt mix specifications. The modifications will ensure that pavements provide the service for as designed time duration and have minimal performance problems that reduce the future rehabilitation and maintenance costs.