Experimental Assessment of Dust Emissions on Compacted Soils Degraded by Traffic

Abstract

Haul traffic on earthworks runways during construction works is an important factor of dust emission. Compacted soils surface become progressively degraded as the number of wheels passing increases. Fine particles are then segregated from the soil surface and lifted when the shear stress generated by the flow above the surface increases, leading to the worsening of air quality and reduction of visibility. Laboratory tests were performed to assess dust emissions on traffic degraded soils. Mixtures of kaolin clay and sand were compacted using a laboratory roller compactor and were degraded using a vehicle simulator. Models describing the evolutions of soil degradation and Particle Size Distribution (PSD) during traffic were established. Then, the velocity profiles above each soil sample were obtained in a wind tunnel. The experimental results were analyzed to determine the Reynolds shear stresses generated by the turbulence of the flow. PSD, degradation and stresses were implemented in the Convective Turbulent Dust Emission (CTDE) model to estimate the dust emission flux of the soils for several passes of the wheel. A comparison between results from the model and field measurements underlines that turbulence is not the main contributor to dust emissions when a vehicle is in motion.

Keywords

• dust emissions
• compacted soils
• traffic degradation
• particle size distribution
• wind tunnel
• turbulence