Experimental Study On Optimization Of Composite Component And Ratio Of Anti-UV Aging Agent In Asphalt Pavement

With the rapid progress of highway construction in China,asphalt pavement which has a good road performance is widely used in this period.However,the intensity of ultraviolet ray in sunlight is greater in some high radiation areas,which leads to accrue some road diseases such as cracks,loose,spalling,pot holes and so on,and these diseases will absolutely affect the road performance and service life of asphalt pavement.Therefore,how to enhance asphalt pavement’s ability of anti-UV aging becomes a burning issue in asphalt pavement design.Based on the research of asphalt UV aging test and evaluation method,an ultraviolet environmental box is invented.It is used to simulate asphalt pavement’s UV aging environment and analyze the relevance between different evaluation indexes and different UV aging influential factors.Combined with the fourier transform infrared spectrometer（FTIR）test,the asphalt UV aging mechanism is studied.SiO₂,organic montmorillonite（OMMT）,layered double hydroxides（LDHs）and powdered styrene-butadiene-rubber（PSBR）are selected as components of composite anti-UV aging agent.Abilities of anti-UV aging of asphalt samples which are prepared by adding each monocomponent material separately are studied by Superpave test.The rheological properties and UV-aging indexes（UVI）of asphalt samples which are prepared by different components composite materials are contrastively evaluated.The optimum proportion of components is optimized by the multiple indexes orthogonal test and a reasonable content of composite anti-UV aging agent in asphalt is determined.The modified asphalt anti-UV aging mechanism is studied by FTIR,scanning electron microscope（SEM）and X-ray diffraction（XRD）.Study results show that UVI has a better relevance with asphalt UV aging influential factors than other evaluation indexes,which could be selected as the asphalt UV aging evaluation index.The ultimate component composite materials are consisted of SiO₂,OMMT and PSBR and their ratio is 4:3.5:3.5.The reasonable dosage of this kind composite material in 70^#asphalt is 12%which leads to the anti-UV aging property can increase more than 22%.FTIR results show the composite anti-UV aging agent efficiently can delay the cracking of asphalt and reduce occurrences of oxidation reactions.XRD results show the composite anti-UV aging agent melting intercalated with asphalt leads to form a partially ordered intercalated nano composite structure,which can efficiently prevent and slow down oxygen enter asphalt and light component volatilize of asphalt when asphalt suffers UV irradiating.Besides,SiO₂ can effectively reflect UV rays,which helps to reduce occurrences of oxidation reactions in asphalt.The composite anti-UV aging agent not only enhances asphalt’s ability of anti-UV aging,but also improves the rheological property of asphalt.Research achievements and evaluation method provide a basis and reference for asphalt pavement resistance to UV aging.