A pin-on-disc study of particles emitted during the tire rubber and road aggregates wear test

Abstract

Tire-road wear results in particulate emission, which can either accumulate at the contact interface or be released into the environment. While previous research has focused on the collection and characterization of Tire-Road Wear Particles (TRWP), offering valuable insights into their properties, less is known about the tribological mechanisms governing TRWP generation and the subsequent modifications to tire-road contact conditions. A novel methodology is introduced that integrates laboratory wear testing with particle collection to analyze the dynamics and mechanisms of TRWP generation. A pin-on-disc tribometer, housed in an isolated chamber, was used to replicate tire-road contact conditions on a reduced scale. An Electrical Low Pressure Impactor (ELPI) system was used to collect and characterize the airborne wear particles generated during testing. The findings provide important insights into the relationship between wear and corresponding emissions. Results are presented in terms of evolution of the coefficient of friction, particle morphology, and number concentration. TRWP morphology evolves throughout the test, with particle increasing from approximately 50 µm at the initial stage to 500 µm at the later stages. The number concentration of airborne wear particles in the 0.6–4 µm size range decreases significantly, from 1.9 particles/cm³ at the initial wear stage to 0.08 particles/cm³ at a later stage, representing a 20-fold higher concentration at the onset of contact. Comparison with previous studies validates the relevance of the developed test method. The results are discussed in the context of particle impact on air quality and road safety, underscoring the importance of accounting for early-stage wear.