Analysis of permanent deformation in asphalt mixtures using Mohr–Coulomb criteria

This study aimed to investigate the influence of the internal friction angle on the mechanical properties and resistance to permanent deformation of asphalt mixtures. Permanent deformation, resulting from vehicular loads, can occur due to densification, use, and flow of the mixture. Considering that the asphalt mixture behaves as a solid material at service temperatures of 40 °C to 60 °C, the Mohr–Coulomb criterion, commonly used to describe shear characteristics of solid materials, was employed to determine the internal friction angle and cohesive intercept of the mixture. An experimental program was devised to assess the mechanical properties associated with the internal friction angle of asphalt mixtures with asphalt binders of the types Petroleum Asphalt Cement with a penetration grade of 50/70 (PAC 50/70) and Petroleum Asphalt Cement modified with styrene–butadiene–styrene (SBS) polymer (E-55/75). Laboratory analyses were conducted to determine shear rupture parameters, using the Mohr–Coulomb theory. It was observed that an increase of 5% in coarse particles resulted in an average gain of 1° in the internal friction angle for each studied gradation range, up to the limit of 30–35% of coarse particles for each mixture. The results indicated that shear rupture parameters, especially the internal friction angle and cohesive intercept, play a crucial role in the resistance to permanent deformation of asphalt mixtures. It was concluded that an increase in the internal friction angle contributes to greater resistance to permanent deformation, providing valuable insights for optimizing the composition of asphalt mixtures in terms of mechanical performance.