Research On Nano-modified Asphalt In The Area With Hot Summer And Cold Winter

Yan Zhiwu Highway is located in Yan’an City and the region where it is passing is hot insummer and cold in winter. In that region, the average annual temperature, maximumtemperature and minimum temperature are9.7℃,39.7℃and-28.5℃respectively, whichcan easily cause rutting and cracking to the pavement. Therefore, the asphalt mixture musthave good high-temperature and low-temperature properties. It is difficult for conventionalasphalt materials to resist both rutting and cracking disease, especially in the region where ishot in summer and cold in winter. For this reason, nano-materials and polymer compositemodified asphalt are adopted to improve the resistance of the pavement to rutting in hightemperature and shrinkage cracking in low temperature, making it suitable in high and lowtemperature environment. Therefore, this research has a very important practical significance.Firstly, five kinds of nanomaterials, including nano-A, nano-B, nano-C, nano-D, andnano-E, were chosen in this research and the appropriate activator was adopted to the surfaceactivation and modification treatment. Then the impacts on the surface activation of these fivenano-materials were tested through the lipophilic degree test and infrared spectrum. Thelipophilic degree test showed that the surface lipophilic degree of every type of thenanomaterial was improved, and the infrared spectrum suggested that the activator wasattached to the surfaces of the nano-materials through chemical bonds. Therefore, theactivator is effective to the surface modification of nano-materials.Secondly, the polymer modified asphalt and nano-material modified asphalt wereprepared through stirring and high speed shearing method, and some traditional indexes ofthese two modified asphalt were tested and compared so as to select the better modifier. Thesame preparation technology was employed to prepare the nano-palymer composite modifiedasphalt through the triple factors orthogonal test and two complementary factors test, and theoptimal combination was selected through the extreme difference analysis and comparingmethod. The performance and fabrication cost were comparatively analyzed, and the optimalcombination of nano-polymer modified asphalt was determined, including four types of combination, such as the incorporation of3%A+0.5%C+3.7%SBS,5%B+1%C+3%SBR,3%A+4%SBR,5%B+4%SBR and5%A+4.2%SBS respectively.Then, the aging property, DSR, BBR and segregation tests were employed to investigatethe performance of the chosen nano-polymer modified asphalt. In the aging test, the mass loss,penetration ratio and ductility were used to evaluate the anti-aging performance of the asphalt.In the DSC test, the complex shear modulus G*, phase angle δ and rutting factor G*/sinδ wereused to evaluate the high-temperature performance of the asphalt. In the BBR test, thebending creep stiffness modulus S and the slope of the creep curve were used to evaluate thelow-temperature cracking resistance of the asphalt. Through these three tests, three types ofnano-polymer modified asphalt were finally determined to be appropriate in the region whereis hot in summer and cold in winter, including the incorporation of3%A+0.5%C+3.7%SBS,5%B+4%SBR and5%A+4.2%SBS. Also, the study indicated that both the low-temperature andanti-aging performance of the asphalt were improved. In the segregation test, the three chosennano-polymer modified asphalt all revealed that the introduction of nano-materials by thesurface activation treatment can evidently improve the compatibility of composite modifiedasphalt.Finally, the distribution of nano-materials and polymer in the final selected modifiedasphalt and the interface condition with the asphalt were observed through the luminescencemicroscope and scanning electron microscope, and the micro modification mechanism of thenano-polymer modified asphalt was analyzed by infrared spectroscopes. In the meantime, theinteraction mechanism of nano-materials and polymer in asphalt was investigated to furtherstudy the technical performance of the nano-polymer modified asphalt, expecting to obtainexcellent modification results, thereby promoting the development and application of thenano-material modified asphalt.