To solve the problem of the pavement being aged due to the influence of temperature, light and other environmental factors are brought in service. Nano-CaCO ₃ surface was activated by 6% KH-550, and nano-ZnO surface was activated by 6% aluminate. Nano-CaCO ₃ /nano-ZnO/SBR composite-modified asphalt was prepared. The optimum proportion of composite-modified asphalt was determined by orthogonal test. The influence of modifiers on asphalt pavement performance was comprehensively studied. The microstructure of composite-modified asphalt was characterized by scanning electron microscopy and infrared spectroscopy. The mechanism of composite-modified asphalt was analyzed. The results show that the optimum combination of composite-modified asphalt is 4% nano-CaCO ₃ + 5% nano-ZnO + 4% SBR, the aging performance of the composite-modified asphalt is reduced by 6.9%, and the viscosity is increased by 14.6–23.1%. The complex shear modulus is increased by 24.1% at 82°C, the stiffness modulus is decreased, on average, by 21.1%. and the creep curve slope is increased by 9% on average. In the meantime, during the preparation process of composite-modified asphalt, it mainly occurred due to chemical reaction with surface-modified nanomaterials and physical change with SBR polymer materials.

In order to improve the mechanical properties and durability of cement-based materials, a certain amount of multi-walled carbon nanotubes (MWCNTs) and polypropylene fiber (PP fiber) were incorporated into cement-based materials. The mechanical properties of the multi-walled carbon nanotubes/polypropylene fiber cement-based materials were evaluated using flexural strength tests, compressive strength tests, and splitting tensile tests. The effects of multi-walled carbon nanotubes and polypropylene fiber on the durability of cement-based materials were studied using drying shrinkage tests and freeze–thaw cycle tests. The effects of the multi-walled carbon nanotubes and polypropylene fibers on the microstructure and pore structure of the cement-based materials were compared and analyzed using scanning electron microscopy and mercury intrusion tests. The results showed that the mechanical properties and durability of cement-based materials can be significantly improved when the content of multi-walled carbon nanotubes is 0.1–0.15%. The compressive strength can be increased by 9.5% and the mass loss rate is reduced by 27.9%. Polypropylene fiber has little effect on the compressive strength of the cement-based materials, but it significantly enhances the toughness of the cement-based materials. When its content is 0.2–0.3%, it has the best effect on improving the mechanical properties and durability of the cement-based materials. The flexural strength is increased by 19.1%, and the dry shrinkage rate and water loss rate are reduced by 14.3% and 16.1%, respectively. The three-dimensional network structure formed by the polypropylene fiber in the composite material plays a role in toughening and cracking resistance, but it has a certain negative impact on the pore structure of the composite material. The incorporation of multi-walled carbon nanotubes can improve the bonding performance of the polypropylene fiber and cement matrix, make up for the internal defects caused by the polypropylene fiber, and reduce the number of harmful holes and multiple harmful holes so that the cement-based composite material not only has a significant increase in toughness but also has a denser internal structure.

The purpose of this study is to further improve the road performance and emission reduction effect of tourmaline-modified asphalt. Graphene was used to enhance the performance of tourmaline-modified asphalt, and graphene/tourmaline-composite-modified asphalt was prepared. The temperature susceptibility, high temperature, anti-aging properties and rheological performance of the modified asphalt were studied. The test method of emission reduction efficiency of the modified asphalt and its mixture was proposed. The emission reduction effect of different modified asphalts and its mixture was evaluated. The enhancement effect of graphene on the properties of tourmaline-modified asphalt was confirmed. It provides a reference for the performance enhancement of inorganic material modified asphalt. The results show that the temperature susceptibility, high temperature, anti-aging properties and rheological performance of the graphene/tourmaline-composite-modified asphalt are better than those of the tourmaline-modified asphalt and base asphalt. The asphalt fume reduction rate of graphene/tourmaline-composite-modified asphalt is higher than that of tourmaline-modified asphalt. With the increase of graphene content, the emission reduction performance increases gradually, and the enhancement effect of graphene on tourmaline performance is more obvious.

To give full play to the advantages of polyurethane as a binder, such as mixing at room temperature, short curing time, and high curing strength, polyurethane was used as the binder of a waste asphalt mixture, and the pavement performance of PCRM (Polyurethane Cold-Recycled Mixture) was analyzed. Firstly, the adhesion performance of polyurethane binder with new and old aggregates was evaluated using the adhesion test. Then, the mix proportion was designed according to the material characteristics, and the reasonable molding process, maintenance conditions, design indexes, and the optimal binder ratio were proposed. Secondly, the high-temperature stability, low-temperature crack resistance, water stability, and compressive resilient modulus of the mixture were evaluated through laboratory tests. Finally, the pore structure and microscopic morphology of polyurethane cold-recycled mixture were analyzed by industrial CT (Computerized Tomography) scanning, and the failure mechanism of polyurethane cold-recycled mixture was revealed. The test results show that the adhesion between polyurethane and RAP (Reclaimed Asphalt Pavement) is good, and the splitting strength of the mixture increases greatly when the ratio of glue to stone reaches 9%. Polyurethane binder has low sensitivity to temperature and poor water stability. With the increase of RAP content, the high-temperature stability, low-temperature crack resistance, and compressive resilient modulus of PCRM showed a decreasing trend. When the RAP content was less than 40%, the freeze–thaw splitting strength ratio of the mixture was improved. After the incorporation of RAP, the interface was more complex and there were many micron-scale holes, cracks, and other defects; after high-temperature immersion, the polyurethane binder appeared to show a certain degree of peeling at the holes of the RAP surface. After freeze–thaw, the polyurethane binder on the surface of the mixture produced many cracks. The study of polyurethane cold-recycled mixture is of great significance to realize green construction.

In order to realize the active melting of ice and snow of poured asphalt concrete on steel bridge deck pavement in winter, graphite and carbon fiber were selected as conductive materials to prepare poured conductive asphalt concrete CGA-10. The influence of the content of conductive phase material on the electrical resistivity variation of poured conductive asphalt concrete was studied. The influence of conductive materials and their content on pavement performance of poured conductive asphalt concrete was analyzed. The heating effect of poured conductive asphalt concrete was studied. And the ice melting efficiency of poured conductive asphalt concrete was evaluated by indoor deicing test. Finally, the microstructure characteristics were analyzed by SEM. Experimental results showed: 0.4% carbon fiber +30% graphite can form a good conductive network in poured conductive asphalt concrete. Carbon fiber can make up for the adverse effect of graphite on the pavement performance of poured conductive asphalt concrete. Heating efficiency of 0.4% carbon fiber +30% graphite poured conductive asphalt concrete can reach 78.85%, and its ice melting efficiency can reach 50.03%. Graphite powder particles are tightly wrapped with asphalt mortar, which reduces the porosity and resistivity of asphalt mixture. On the one hand, carbon fiber makes up for the interruption of graphite particle conductive chain, on the other hand, it plays a reinforcing role.

In order to improve the durability of asphalt pavement and prolong the service life of heavy traffic asphalt pavement, graphene oxide (GO) and rubber powder (RP) were used as composite modifiers to modify matrix asphalt. The high-temperature rheological properties of composite-modified asphalt at different temperatures and frequencies were analyzed. The influence of different stress levels on the viscoelastic properties of composite-modified asphalt was evaluated. The low-temperature rheological properties of composite-modified asphalt were studied. The difference between RP-modified asphalt and GO/RP composite-modified asphalt was analyzed, and the mechanism of GO and RP on asphalt modification was explored. The results show that the composite-modified asphalt has good rheological properties at low temperature, relatively smooth surface and stable network structure, which improves the segregation problem of RP in matrix asphalt. At present, GO and RP are rarely used as composite modifiers to modify matrix asphalt at home and abroad, which is an innovation in material selection.