Developing a Short-Term Aging Protocol for Warm Mix Asphalt Binders: A Study Integrating Laboratory and Field Findings

Abstract

This study examined the effectiveness of the laboratory short-term aging process for warm mix asphalt (WMA) binders using response surface methodology (RSM) with various combinations of aging parameters: time, temperature, airflow, and binder weight. The research aimed to enhance understanding of aging parameter efficacy and propose a modified laboratory short-term aging protocol that accurately simulates plant short-term aging in WMA binders. To this end, three WMA mixtures produced at 135°C were collected from plants, and their asphalt binders were extracted and recovered. Virgin binders from the same projects were also obtained and two of them aged in a rolling thin film oven at different combinations of aging parameters, designed by RSM. High-temperature performance grade (PG) and carbonyl index were used as model responses to quantify laboratory aging levels. These parameters were also assessed in the plant extracted binders to establish target values. The statistical analysis revealed significant effects of time, temperature, and weight, as well as their interactions, on key rheological and chemical properties of binders, while the airflow rate effect within the studied range was found to be insignificant. A modified protocol for laboratory short-term aging of WMA binders was developed, showing consistency with plant short-term aged binder results. The model was successfully validated using chemical and rheological assessments of a third binder aged with the proposed protocol.