The Influence of Compaction Method on the Microstructure of an Asphalt Mixture Using 2D Digital Image Processing

Objective: Apply a two-dimensional digital image processing technique to analyze the influence of Marshall and field compaction methods on the microstructural arrangement of asphalt mixtures, evaluating the spatial distribution, orientation, and gradation of aggregates. Theoretical Framework: This research is based on 2D image processing techniques for microstructural characterization, drawing upon parameters established by Hartmann (2017) for virtual sieving simulation and studies by Yucel (2024) regarding particle orientation validation. Method: Four samples compacted using the Marshall method and four samples extracted from a roller-compacted pavement were analyzed. The samples were sectioned, digitized, and processed using the ImageJ software to obtain particle area, area fraction, and Feret diameter. This data facilitated sieving simulation and orientation analysis. Results and Discussion: The Marshall samples exhibited consistent gradations among their slices, whereas field samples showed significant variations. Both sets of samples presented distinct gradation curves compared to the design curve and similar aggregate orientations. No direct influence of the compaction method was identified, and the segregation verification proved inconclusive due to methodological uncertainties. Research Implications: Digital image processing proved to be a tool with high potential for the analysis of road materials. Furthermore, the results indicate that Marshall and field compaction produce microstructural disparities that may influence the mechanical performance of pavements. Originality/Value: This study contributes to the literature by validating an accessible technique for detailed microstructural evaluations, integrating computational advancements to enable analyses that are not feasible through conventional methodologies.