Exploiting epoxidized cashew nut shell liquid as a potential bio-additive to improve asphalt binder performance

Abstract

The objective of this work is to evaluate the potential of cashew nut shell liquid (CNSL) as a renewable resource and low-cost raw material for the synthesis of bio-based epoxy for asphalt binders. The epoxidized material named ECL was synthesized via chemical modifications in alkyl phenols present in CNSL – a good alternative of petrochemicals based on phenols to replace the toxic bisphenol A, currently used to synthetize epoxidized products. The additive was structurally characterized by Nuclear Magnetic Resonance (1H NMR and 13C NMR), and Fourier Transform Infrared Spectroscopy (FTIR), presenting results in accordance with the epoxidation reactions. Testing was conducted on asphalt binder with 10% and 20% of epoxidized CNSL to explore the influence of bio-epoxidized additives on the properties of binder, both unaged and RTFO-aged conditions. The Rotational Viscosity, Dynamic Shear Rheometer (DSR) and Binder bond strength (BBS) tests were utilized. The viscoelastic behaviour of epoxy modifier asphalt presented higher viscosity than neat asphalt binder. The rheological parameters from DSR showed that the epoxy modifiers enhance the elasticity of the binder, suggesting the presence of polymer elastic networks in modified binders. The rutting resistance of epoxidized modified binder at the high temperature was evaluated by Multiple Stress Creep and Recovery (MSCR) test, while the fatigue life was analysed by Linear Amplitude Sweep (LAS) test. The MSCR results indicated that the 10% of the ECL additive, increasing rutting resistance, while the LAS test showed that fatigue resistance of AB-10% ECL was positively affected by epoxidized CNSL additive. BBS results showed that the aged AB-10% ECL has the highest binder bond strength. Furthermore, the use of renewable energy resources is a strong incentive towards the development of less pollutant technologies.