Novel Bio-Nanocomposite for Asphalt Pavements: Montmorillonite Intercalated with Castor Oil

This study introduces an innovative bionanocomposite to enhance the sustainability of asphalt pavements. The bionanocomposite is made from montmorillonite clay and castor oil. Preswelling of montmorillonite clay in an isopropanol/water mixture facilitated intercalation of castor oil into the clay interlayer space and the subsequent replacement of castor oil with asphalt molecules. The displaced oil molecules plasticized the asphalt matrix, thereby improving the asphalt's workability and resistance to low-temperature cracking. The clay particles reinforced the asphalt matrix, enhancing its resistance to permanent deformation at high temperature. It was found that the synergistic use of montmorillonite and castor oil led to significant enhancement in asphalt's properties owing to partial hydrolysis of castor oil and the formation of ricinoleic acid, which formed strong hydrogen bonds and ion–dipole bonds with the montmorillonite surface. The study provides insights into the underlying mechanisms leading to the synergistic role of montmorillonite and castor oil in the asphalt matrix. The study outcome promotes the use of naturally occurring resources to enhance sustainability and resource conservation while improving the properties of asphalt pavement.