Investigation of Epoxy Resin Effects on the Stripping Damage in Bitumen-Aggregate Systems Using their Thermodynamic and Mechanical Characteristics

Stripping damage is an important factor that affects the longevity of asphalt pavements. The bitumen and asphalt pavement industry has introduced various technologies and additives aimed at creating durable asphalt pavements with extended lifespans. One such additive is epoxy resin. Evaluating the behavior of asphalt mixtures containing epoxy resin against stripping damage is, therefore, essential. This study examined the stripping resistance of asphalt compositions incorporating bitumen and four types of aggregate (basalt, sandstone, limestone, and siliceous), modified with 5% to 20% epoxy resin, through their thermodynamic and mechanical properties. In the thermodynamic analysis, energy parameters reflecting the wetting and adhesion characteristics of the asphalt mixtures were determined by measuring the surface free energy of the bitumen and the aggregates. For the mechanical evaluation, indirect tensile strength was assessed based on AASHTO-T283 to estimate the tensile strength ratio values for the asphalt specimens. As the study results show, adding epoxy resin improves the wetting and adhesion performance of asphalt compositions containing limestone, siliceous, and basalt aggregates. Improvements in performance were also noted for sandstone compositions, but only at a 5% epoxy resin content. This suggests that epoxy resin does not effectively enhance the bitumen-aggregate adhesion mechanism in mixtures containing sandstone aggregate. Furthermore, the findings indicate that the thermodynamic traits (adhesion and wetting) affecting mechanical performance vary with different percentages of epoxy resin and types of aggregate.