Laboratory and Field Patching Performance of a Half-Warm Mix Using Waste Cooking Oil–Based Biobinder with Reclaimed Asphalt Pavement

Abstract

In this study, a new half-warm mix patching material was developed using polymerized waste cooking oil (WCO)-based biobinder with 100% reclaimed asphalt pavement (RAP). Laboratory tests were conducted on this bio-RAP mixture to evaluate the rheological performance of the fully blended biobinder and recovered RAP binder at varying weight ratios. The influence of biobinder dosage and production temperature (90°C and 100°C) on the mechanical performance of the bio-RAP mixtures were evaluated using an indirect tensile (IDT) strength test, the Hamburg wheel track test (HWTT), and the interlayer shear bonding strength test. The designed bio-RAP mixtures were used to patch pavement potholes in the field. The results showed that the WCO-based biobinder softened the stiff RAP binder but that biobinder dosage should be limited to 50% in the blended binder. This is because the biobinder can compromise the elasticity and ductility of the blended binder at high and low testing temperatures, respectively, when the dosage of the biobinder exceeds 50% of the blended binder. The biobinder can function as both a recycling agent and a binding agent in bio-RAP mixtures. With an increase in biobinder dosage, the IDT test strength of the bio-RAP mixtures decreased and the cracking tolerance index (CTindex) increased. Higher production temperature enhanced blending between the biobinder and RAP binder and improved the integrity of the bio-RAP mixtures. This is beneficial for improving resistance to rutting and moisture damage. All evaluated bio-RAP specimens had sufficient bonding strength with the base asphalt mixture; this demonstrates the potential of the bio-RAP mixture as a long-lasting patching material. The field pothole patching work showed that biobinder dosage, production temperature, and pothole shape are critical factors for increasing the lifespan of the bio-RAP mixture as a half-warm mix patching material.