Optimized formulation of asphalt compound containing bio-oil and shredded rubber

Abstract

Under the influence of complex environments and increasing traffic loads, asphalt pavements expose early failure due to the dependence of asphalt on temperature and loading-rate. This problem has been investigated to some extent by preparing modified asphalts. In order to obtain high-performance and sustainable asphalt materials, this study focused on using biomass oil (BO) such as castor oil, and solid waste materials such as crumb rubber (CR) to replace a part of the base asphalt. Based on the general physical properties of the modified asphalt, the order of adding the two modifiers was determined. To obtain the modification process with the best compatibility between BO and asphalt, the storage stability test, atomic force microscopy and differential scanning calorimetry were used as evaluation indexes. Similarly, orthogonal experiments were designed to obtain the best preparation process of BO/CR modified asphalt based on the evaluation indexes such as softening point, ductility and elastic recovery tests. Results showed that the softening point and elastic recovery of BO/CR modified asphalt prepared by adding BO first and then adding CR increases by 3.8 °C and 10.5%, respectively. The BO modified asphalt showed good compatibility of each component in terms of macroscopic properties, microscopic morphology, and thermodynamics at a preparation temperature of 140 °C, shearing time of 30 min, and shearing rate of 5000 rpm. The optimal preparation process of BO/CR asphalt composite with excellent performance was determined by multi-index orthogonal test, and that is, the swelling time was 90 min, the shearing time was 60 min, and the breeding time was 60 min. This study elucidated the effect of modifier addition order on the physical properties of modified asphalt. The influence of the preparation process on the compatibility of BO/CR with asphalt was revealed from multiple perspectives. A high-substitution and high-performance modified asphalt preparation process was obtained, which laid the foundation for the sustainable development of asphalt.