Evaluating Segregation of Hot In-Place Recycled Pavement Based on Surface Texture Distribution Characteristics

As a pavement maintenance technology, hot in-place recycling (HIR) can realize full utilization of reclaimed asphalt pavement (RAP), significantly saving non-renewable resources and project costs. However, due to variability of material properties, recycled mixtures gradation, and temperature control in construction, HIR-maintained pavement usually suffers from segregation, affecting performance and service life. To control construction quality and prolong service life, a segregation evaluation system of HIR-maintained pavement is proposed. This evaluation system, including calculation of segregation indexes, determination of segregation zones, and discrimination of segregation types, is established based on digital image processing (DIP) and surface texture distribution characteristics. In addition, it is verified by a case study of qualified HIR projects in Jiangsu Province in China. According to the empirical acceptance requirements of maintenance projects, discriminative zones for segregation types are established at 95% confidence level. Fluctuation curves of segregation indexes and image tests of four segregation types identified by segregation zones show that segregation indexes are well correlated with texture distribution characteristics and segregation degree, confirming the effectiveness and accuracy of the segregation evaluation system. Therefore, the segregation evaluation system of HIR-maintained projects proposed in this paper can realize real-time monitoring, rapid diagnosis, evaluation, and treatment decision-making of recycled pavement segregation degree.