Effect Of Modified Graphene Nanoplatelets On Properties Of SBS Modified Asphalt And Its Mixtures

As a kind of flexible pavement,asphalt pavement has been widely used in high-grade highways of various countries since its discovery.However,many road defects such as rutting and cracking have occurred,with the traffic pressure increases,due to insufficient performance of the early asphalt pavement.The polystyrene-poly'butadiene-polystyrene(SBS)modified asphalt which used the SBS as modifier is widely used in the construction of local high-grade highways due to its excellent mechanical properties properties.But in the face of increasing traffic pressure,SBS modified asphalt is gradually"overwhelmed".Graphene(GNP),as one of the emerging nanomaterials,has mechanical properties comparable to that of steel.Graphene nano nanoplatelets(GNPs),as a stack of multilayer GNPs,have similar mechanical strengths and less costly.Therefore it has the potential for large-scale applications.Studies have shown that the addition of GNPs can significantly improve the mechanical properties of asphalt,but there are still some problems such as low temperature performance and insufficient compatibility.Based on the above problems,this paper firstly modified SBS asphalt with unmodified GNPs.The performance tests showed that the performance of GNPs/SBS modified asphalt has a peak value(0.05%of GNPs added),and segregation test showed that higher levels of GNPs may cause compatibility problems in the asphalt.Secondly,the polystyrene grafted GNPs(PS-GNPs),octadecyl amine grafted GNPs(ODA-GNPs)and thiolated GOs(GOs-SH)were prepared to modify SBS asphalt starting from two physical modification methods based on the principle of similar solubility and the principle of surface activity,and one chemical modification method based on the click chemistry(thiol-ene reaction).The performance tests showed that the addition of three modified GNPs can improve the performance of SBS modified asphalt and mixture to varying degrees.The best modification effect is PS-GNPs that the addition of 0.02%PS-GNPs can increase the elastic properties of SBS modified asphalt by 37.5%,the high temperature anti-rutting performance by 112.6%,the fatigue resistance by 274.9%,the water resistance performance of the mixture was effectively improved and the anti-rutting performance was improved by 44.4%.While the modification effect of PS-GNPs on SBS modified asphalt decreased with the increase of its addition amount,which is the same as the change trend of GOs-SH content.In contrast,the performance of ODA-GNPs/SBS modified asphalt increases with the addition of ODA-GNPs.Finally,the actionla mechanism of three modified GNPs in SBS modified asphalt was investigated by microscopic characterization methods.Among them,PS-GNPs and ODA-GNPs can be physically combined with SBS molecular chains to form a specific composite network structure.While the GOs-SH can be grafted in a asphalt environment by a thiol-ene click reaction with a specific position on the SBS(1,2-C=C),thereby chemically linking a plurality of SBS molecular chains to form a specific composite network structure.Compared with the ordinary SBS network,the three kinds of special composite networks have higher mechanical strength which make the the performance improvement of the asphalt and its mixture on macro perspective.