Enabling high-RAP-content recycling in asphalt pavements through epoxy modification: Durability and life cycle assessment

High RAP (Reclaimed Asphalt Pavement) content often causes performance deficiencies in recycled asphalt pavements. Epoxy modification is a promising solution, but its long-term durability and lifecycle benefits have yet to be fully demonstrated. Therefore, this study aims to evaluate the durability and lifecycle benefits of epoxy-modified recycled asphalt mixtures (ERAM), using epoxy asphalt mixtures (EAM) and general recycled asphalt mixtures (GRAM) as controls. ERAM's durability was assessed via laboratory mechanical tests, service life predictions, and field observations. A comprehensive lifecycle cost and carbon emissions analysis was conducted across multiple pavement schemes, considering complete lifecycle stages and data variability. Results show that ERAM with 60 % RAP substitution achieves a fatigue endurance limit of 191 με, substantially exceeding the field tensile strain of 53 με. Based on mechanical-empirical models, ERAM is predicted to have a service life of 27–29 years, about 170 % that of GRAM. With enhanced durability and higher RAP content, ERAM reduces annual lifecycle costs and carbon emissions by 10 % and 30 % compared to EAM and GRAM, respectively. These findings demonstrate ERAM's potential as a durable and sustainable pavement alternative.