A Non-Contact System to Detect and Quantify Segregation in Hot Mix Asphalt Pavements

Current Hot Mix Asphalt (HMA) pavements are designed to withstand expected traffic and environmental conditions for a particular roadway section. Segregation, or lack of homogeneity (uniformity) in the in-place HMA constituents, has been identified by the asphalt industry as one of the most common problems associated with premature failure of HMA pavements. Segregation leads to accelerated pavement distresses, which translates in a reduction in the level of performance and service life of the pavement. Therefore, HMA Quality Assurance procedures usually include provisions to detect and quantify the presence of this problem in newly constructed pavements. Traditionally, visually identified areas of non-uniform surface texture have been classified subjectively as segregated HMA and, therefore, as bad construction. To reduce the subjectivity involved in the quality assurance, an automatic measurement-based process is necessary. This paper presents a new methodology to detect and quantify HMA segregation using digital image analysis. The main objective of the non-contact system presented in this paper is the detection of segregated HMA areas and the identification of the locations of these areas along a road for HMA quality assurance purposes. The system uses relatively low cost off-the-shelf components for capturing images of pavement and innovative image processing and analysis software to automatically detect changes in the surface appearance due to segregation. The system can be used stand-alone or in combination with current laser-based systems for pavement quality assurance and has the potential to reduce the subjectivity in the HMA inspection process in addition to providing a permanent and periodic record of captured images, thus enhancing pavement quality assurance practices.