The effect of mineralogy, texture and mechanical properties of anti-skid and asphalt aggregates on urban dust, stages II and III

Urban road dust is formed during wintertime when cars use studded tyres and when anti-skid aggregate particles are being crushed under tyres. A road simulator fitted with studded and friction winter tyres was used in three test series in order to investigate dust formation at tyre and pavement interface with various anti-skid materials and tyre types. The bedrock and glaciofluvial anti-skid aggregates tested had variable mechanical-physical and mineralogical properties. A special emphasis was put on the particle size distribution of anti-skid materials and on asphalt aggregate characteristics. The proportions of particles < 10 mu m from asphalt vs anti-skid aggregate was defined with SEM/EDX. The results of this study indicate that the particle size distribution is the most important property of anti-skid aggregates, and that the wearing process of asphalt pavement "is not homogenous" with friction and studded tyres, and with various anti-skid aggregates. The mechanical-mineralogical relationship between anti-skid and asphalt aggregates is one decisive factor in PM10 formation and these properties affect the proportions of PM10 (anti-skid vs asphalt aggregate). Friction tyres and anti-skid aggregates with lower average hardness compared to asphalt aggregate cannot wear harder minerals (e.g., quartz) of the pavement aggregate homogeneously.