Exploring generic fractions of multi-origin asphalts and revisiting the linkage to their bulk properties via machine learning

Significant efforts have been made to investigate the relationship between generic fractions and bulk properties of asphalt, as the most used binder in road pavement engineering. However, due to limited data availability, advanced data mining techniques, such as machine learning (ML), have rarely been applied in the field. This study aimed to collect extensive data on asphalt generic fractions and bulk properties and to explore their underlying linkage using ML methods. A total of 800 datasets for asphalt fractions of the saturate, aromatic, resin, and asphaltene (SARA) were collected and analyzed across various asphalt types. The generic fractions and derived indexes were used as input variables in ML models to predict key asphalt properties, including penetration, softening point, rutting factor, and rotational viscosity. The contribution of different generic fractions, derived indexes, and additional variables (e.g., asphalt type and geographical origin) to these properties was quantified using the SHapley Additive exPlanations (SHAP) technique. Among the ML models evaluated, Adaptive Boosting (AdaBoost) showed the best predictive performance, while the support vector machine (SVM) demonstrated greater robustness. SHAP analysis revealed that penetration was primarily influenced by the proportions of asphaltenes and saturates, while asphaltene content and the asphaltenes index were the most significant predictors for other properties, such as softening point, rutting factor, and rotational viscosity. Including asphalt type and geographical origin as categorical variables in the models further improved prediction accuracy. This study highlights the potential of ML techniques in uncovering complex relationships between asphalt fractions and their bulk properties, surpassing conventional statistical approaches, though challenges remain.