Effect Of Surface-Modified Inorganic Nanomaterials On Ultraviolet Aging Resistance Of SBS Modified Asphalt

The development of road transportation is rapid in China,and the application of styrene-butadiene-styrene block copolymer（SBS）modified asphalt pavement is most mature and extensive.SBS modified asphalt is also facing the problem of aging and performance degradation,which leads to a series of pavement diseases,affecting the service life of pavement.Ultraviolet radiation is the main environmental factor of asphalt aging,especially the"Belt and Road"policy of our country has promoted the highway construction in the west of China,which puts forward higher requirements for asphalt anti-ultraviolet aging performance.Nano titanium dioxide（TiO₂）and layered double hydroxides（LDHs）have both UV absorption and shielding properties,and are often used to improve the ultraviolet aging resistance of asphalt,however,it has some problems such as poor dispersion in asphalt and limited anti-ultraviolet effect.In order to solve these problems,TiO₂ and LDHs were modified to prepare two kinds of anti-ultraviolet aging agents,TiO₂/polystyrene-graphene oxide（TiO₂/PS-rGO）and isophorone diisocyanate-LDHs（IPDI-LDHs）,and then the composite modified asphalt was prepared,the influence of two modifiers on the ultraviolet aging resistance of asphalt was evaluated from the aspects of physical property,rheological property and microstructure.The main conclusions are as follows:（1）Microscopic characterization of the modifier:TiO₂ was uniformly distributed on the rGO lamellar structure,PS was grafted on the surface of TiO₂/rGO,and the modified TiO₂ showed higher UV absorption,and the IPDI reacted with-OH on the surface of LDHs through-NCO,the surface modification of LDHs is realized without destroying the interlayer structure of LDHs.（2）Anti-ultraviolet aging performance of modified asphalt:through the evaluation of various aging indexes,SBS modified asphalt with modified agent shows a lower aging degree,has good anti-ultraviolet aging performance,and the deterioration of SBS has been improved.（3）Anti-ultraviolet aging mechanism:TiO₂/PS-rGO has higher ultraviolet absorption than TiO₂,rGO blocks oxygen penetration in asphalt,PS segment promotes the compatibility of modifier and asphalt,and improves the anti-ultraviolet aging performance of asphalt;LDHs can effectively shield and absorb ultraviolet ray,and-NCO of IPDI can establish three-dimensional network structure of polymer,which is beneficial to disperse IPDI/LDHs in asphalt,alleviating ultraviolet aging of asphalt.