Research On Properties Of Asphalts Modified By European Rock Asphalt And Its Composite

European rock asphalt(ERA)is widely used in scientific research and engineering because of its good stability,high temperature anti rutting performance and low price.As one of the most commonly used road modifiers,SBS can significantly improve the durability,high temperature rutting resistance and low temperature crack resistance.Dioctyl phthalate(DOP)can significantly improve the low-temperature ductility and flexibility of asphalt,which has been paid more and more attention in asphalt research.In this paper,a variety of rock asphalt modified asphalt was prepared to comprehensively evaluate the performance change law of rock asphalt modified asphalt.In order to improve the low-temperature performance of rock asphalt modified asphalt,variety of rock asphalt SBS composite modified asphalt and rock asphalt DOP composite modified asphalt were also prepared,in order to explore its basic properties and rheological properties.Through the research results of asphalt and asphalt mixture,the recommended amount of rock asphalt and its composite modified asphalt was obtained.First of all,the ash test and asphalt content test of European rock asphalt were carried out in this paper.It was found that European rock asphalt is composed of 80.50% natural asphalt and 19.50% mineral impurities.In this paper,the conventional performance test and storage stability test of rock asphalt and its composite modified asphalt were carried out.The results show that both rock asphalt and SBS can reduce the storage stability of asphalt,but the amount of rock asphalt and SBS should be limited.Moreover,the addition of DOP can effectively improve the storage stability of asphalt.Secondly,the rheological properties of rock asphalt and its composite modified asphalt were studied.The results show that the addition of rock asphalt can improve the high temperature performance and rotational viscosity of asphalt,and the fatigue performance first increases and then decreases with the increase of rock asphalt content,but it will reduce the low temperature performance of asphalt.The addition of SBS can further improve the high temperature performance and rotational viscosity of rock asphalt modified asphalt,and the fatigue performance increases with the increase of SBS content,and it can also improve the performance of rock asphalt modified asphalt.The addition of DOP can reduce the high temperature performance,rotational viscosity and fatigue performance of rock asphalt modified asphalt,but can improve the low temperature performance of rock asphalt modified asphalt.Thirdly,in order to explore the chemical properties and modification mechanism of rock asphalt modified asphalt,the micro test was carried out.The results show that the rock asphalt modifier can melt well in the matrix asphalt.After melting,the particle size becomes smaller and the distribution is uneven,and it presents three distribution forms: granular,agglomerated and flocculent.From the perspective of chemical properties,the main modification mechanism of rock asphalt is the enhancement of hydrogen bond and Van der Waals force caused by carbonyl and sulfoxide groups,and the stress concentration caused by silica particles.From the perspective of molecular weight,the modification mechanism of rock asphalt is the addition of rock asphalt,which basically does not affect the relative proportion of small molecular weight components,reduces the medium molecular weight components and increases the large molecular weight components.Finally,this paper carries out the asphalt mixture test on the rock asphalt modified asphalt.The results show that the addition of rock asphalt can significantly improve the high temperature stability,high temperature deformation resistance and water stability of asphalt mixture.