Evaluation of Bio-based Castor Oil Additive in Improving the Rheological Properties of Asphalt Binder

The development of road infrastructure is indeed a critical component for the economic growth and quality of life improvements in modern societies. However, the construction and maintenance of conventional asphalt roads have significant environmental impacts, including high energy consumption, greenhouse gas emissions, and the use of non-renewable resources. The urgent need for sustainable solutions in road infrastructure is driven by the necessity to mitigate these impacts. In this context, this study investigates the epoxidation of castor oil and its application as a bio-additive in asphalt binders, focusing on rheological properties. The tests revealed that the epoxidized castor oil (ECO) modification can better resist rutting, meaning that the material becomes more elastic and less prone to permanent deformation, which is a desirable property for asphalt. Furthermore, an increase in the fatigue resistance of the modified samples was observed, particularly at a concentration of 2%, which showed to be more resistant to cracking. The results of this research suggest that bio-based additive derived from castor oil in asphalt binders aligns with the growing trend towards sustainability in the construction industry.