Preparation And Properties Of Vermiculite And Nano-titanium Diocxide Modified Bitumen

In the service process, asphalt pavement will be aging effected of heat, oxygen, light, water and load. Aging of asphalt will influence its performance. It is of great significance to improve the aging resistance of asphalt for prolonging the service life of asphalt pavement, reducing its maintenance cost and saving petroleum resources. Inorganic nanoparticles could be used to improve the ultraviolet aging property because of ultraviolet shielding effect.With the characteristic of large specific surface area, silicate modified asphalt will form an intercalated or exfoliated nano-composite structure. This structure extends the oxygen transmission in the asphalt, delay the oxidation of asphalt and enhance the anti-aging property of asphalt. In this paper, vermiculite and nano-TiO₂ compound modifier was used to modify the asphalt. The physical and rheological properties of compound modified asphalt were analyzed and the effect of compound modifier on the thermal aging resistance and ultraviolet aging properties were researched.X-ray diffraction showed the layer spacing of vermiculite increased from 1.42 nm to 4.39 nm after intercalation and compatibility of vermiculite and asphalt was improved. Conventional test results show that the compound modifier improved the high temperature stability of asphalt. But compound modifier made the ductility of asphalt decrease. The fatigue factor of compound modified asphalt was lower than that of original asphalt. It showed that the fatigue cracking resistance of compound modified asphalt was better. Storage stability test indicated that the storage stability of compound modified asphalt was better.The short-term aging was simulated by the rolling thin film oven, and the properties of asphalt after RTFOT aging were tested. The results showed compound has higher residual penetration ratio and phase angle aging index, lower softening point increment, the Brookfield viscosity increase rate and complex modulus aging index. The results showed that short-term thermal aging resistance was improved by the compound modifier.The long-term aging was simulated by the pressure aging vessel. The results showed the compound modifier was good of the long-term thermal aging resistance of the asphalt. The bending beam rheometer test results of compound modified asphalt after pressure aging vessel aging showed stiffness modulus and stiffness change rate of modified asphalt were similar to original asphalt. It indicated that compound modifier would not cause the low temperature anti-cracking performance of asphalt reduced significantly.Accelerated ultraviolet aging and natural aging are both used to simulate ultraviolet aging of asphalt in the process of using. Routine tests of the sample after two aging methods were taken. In the process of accelerated ultraviolet aging and natural aging, the aging speed would become more and more slowly though the aging time. The ultraviolet aging properties of modified asphalt were greatly influenced by the content of modifier and the best content of compound modifier was 1% organic and 3% nano-TiO₂.For natural aging, all content of compound modifier improved the ultraviolet aging resistance.Integrated effects of compound modifier on the physical and rheological properties and aging resistance of asphalt with different content in different method, the best content of compound modifier is 1% organic vermiculite and 3% nano-TiO₂.