Laboratory Evaluation of Mechanical Properties of Asphalt Mixtures Exposed to Sodium Chloride

Abstract

Spreading sodium chloride salt is one of the most effective operations to tackle ice formation on the surface of a road pavement during cold seasons, thus ensuring safer driving conditions. However, in addition to negative environmental impact, sodium chloride solution could influence the properties and durability of asphalt mixtures. Based on these premises, this laboratory study aims to characterize the mechanical properties of different asphalt mixtures exposed to sodium chloride solution. Four types of asphalt mixtures were immersed in 10 wt% sodium chloride solution for four cycles. The macroscopic surface, moisture absorption, Marshall stability, Marshall quotient, dynamic modulus, and resilient modulus were evaluated. The behavior of the asphalt mixtures was severely deteriorated by the exposure to sodium chloride solution and immersion cycles, resulting in damaged surface, loose structure, degraded stability, and stiffness. The mixture with polymer modified asphalt binder showed the best overall performance. Traditional asphalt mixtures with neat bitumen showed a better performance to resist sodium chloride solution compared with stone mastic asphalt mixtures with neat bitumen because of their dense structure, whereas traditional asphalt mixtures with polymer modified bitumen had a sensitivity to sodium chloride solution similar to that of stone mastic asphalt mixtures with polymer modified bitumen. Based on the findings of this study, using asphalt mixtures with polymer modified bitumen is recommended when road maintenance operations entailing the use of sodium chloride are envisaged.