Reflectance spectroscopy of asphalt pavement under moisture and diesel perturbations: A laboratory study

Moisture pooling and diesel contamination on asphalt pavements can both affect safe road operation by significantly attenuating the skid resistance. In addition, the latter can cause structural integrity issues and leach into nearby natural environment causing a range of soil and water pollution issues. Consequently, monitoring and assessment of moisture pooling and diesel spillage is important for safe and sustainable road transport infrastructure. In this study, a well-controlled laboratory investigation was conducted to establish the feasibility of reflectance spectroscopy in detecting the presence of moisture and diesel on different asphalt mixture samples. Metrices involving the maximum depth of absorption and area of the absorption features in the continuum removed spectra were developed, mainly around wavelengths known to be precursors of moisture (λ ≈ 1400 nm and λ ≈ 1900 nm) and diesel (λ ≈ 2300 nm) presence. Binary formulations for the metrices at relevant wavelengths were developed that can be used to assess moisture pooling on asphalt pavements. For diesel detection, a comparative approach was suggested, requiring availability of baseline continuum removed spectral libraries of asphalt pavements. It is anticipated that this study will assist in future developments of proximal road condition assessment technologies using reflectance spectroscopy.