Comparative Investigation of Hot-Applied and Emulsion-Based Chip Seal Treatments Using Image Processing Techniques and Performance Tests

Abstract

Chip seal can be constructed by using either hot-applied binder or emulsion. Some road agencies use hot-applied binder, whereas others use emulsion. Road agencies sometimes face challenges in choosing the right application rate when switching between hot-applied and emulsion-based chip seals. Hence, there is a need to perform an objective comparative study to evaluate the performance of these chip seal treatments. This will provide agencies with an in-depth understanding of each material and provide guidance regarding important considerations if and when they choose to switch between the materials. This study performed a comprehensive laboratory evaluation of hot-applied and emulsion-based chip seals at different binder, emulsion, and aggregate application rates. Image processing techniques were used to evaluate the microstructure (percentage embedment and chip seal aggregate orientation), which helped explain the resultant effect on aggregate loss as well as bleeding. Furthermore, a low-cost method was developed to compute the macrotexture of chip seals using smartphone images. This method was applied to evaluate the change in macrotexture with bleeding for hot-applied and emulsion-based chip seals. This study led to important conclusions that can help road agencies to proceed confidently when switching between hot-applied binder and emulsion materials.