Laboratory evaluation of diesel damage on asphalt surfaces

Abstract

This laboratory study assessed the suitability of the road surface hardness device, the wheel tracking machine and the pendulum tester to quantify the impact of diesel spillage on an asphalt surface. A Stone Mastic Asphalt (SMA) surface course mixture, typically used in the UK road network, was used in the study. Asphalt specimens were prepared in the laboratory using a roller compactor. Diesel was then poured on to the surface of the asphalt specimens at different levels, 2, 4, 6 and 8 l/m2. Surface hardness measurements were carried out at 20 °C on asphalt specimens with various diesel spillage levels. Wheel tracking tests, on the other hand, were performed at 45 °C on asphalt specimens conditioned for 2 and 24 h at various diesel spill levels. Skid resistance measurements were taken when the surface of the asphalt specimen was dry, after wetting the asphalt specimen with water and after pouring diesel on to the asphalt surface. Results indicated that although the road hardness probe was able to provide some measure of the softening of the asphalt surface as a result of diesel damage, it could not provide a clear indication on the evolution of the damage with time or volume of diesel spilled. Wheel tracking data, on the other hand, provided valuable information of the effect of diesel on asphalt deformation. Moreover, skid resistance measurements using the pendulum tester showed a dramatic loss of skid resistance of the asphalt surface after a diesel spill.