High Modulus Asphalt (EME) Mixes for Cold Climate: HPAC Ongoing Cooperative Research Project

摘要

This paper presents a part of a research program on the use of ME pavement design software for pavement structure that includes HPAC. In the first part of this paper, an explanation of the problematic related to the determination of the pavement's layers thicknesses for the different pavement design software is elaborated. Then, the schedule and the technical details of each of the two phases of the research project, as well as the first results are presented. The initial analysis of the fatigue tests performed in 2 or 4 points bending, and in Tension/Compression (T/C) show that the choice of the fracture criterion influences the fatigue curve coefficients used in M-E pavement design software. The results show that if the fatigue life is associated with the moment when macro cracks appear inside a specimen (N_(f_crack)) rather than being associated with a 50 percent drop in modulus (N_(f50%)), the fatigue curve's coefficients are accurately correlated, and the coefficients of the fatigue curve are comparable for the three standard test methods studied. It appears that the determination of the phase angle between the evolution of the stress and the strain must be rigorously defined during the test to determine the value of N_(f-crack).