| With the continuous increase of traffic volume,large-scale vehicles,increasingly serious heavy loading and the emergence of extreme weather environment,more and more asphalt pavements have rutting,cracking and other problems.Ordinary matrix asphalt has been unable to meet the increasingly stringent requirements of the pavement.At present,polymer modification is the most widely used method to improve the performance of matrix asphalt,but because of the poor compatibility between polymer and asphalt,it can not effectively improve the performance of asphalt and affect the storage stability of asphalt at the micro level.these shortcomings lead to its limitation in practical application.Nano-materials can improve the compatibility of polymer and asphalt,and the performance of some aspects can be effectively enhanced by adding nano-materials to asphalt.However,the nano-modified asphalt is only mixed into the matrix asphalt by simple physical mixing,so it is difficult to take into account the high and low temperature,anti-fatigue,anti-aging and other properties of the asphalt.In order to ensure that polymers and nanomaterials can give full play to their respective advantages,the preparation of nanomaterials/polymer composite modified asphalt by adding polymer modifiers and nanomaterials into asphalt at the same time is the new trend and key direction of the development of modified asphalt.Through analysis and comparison,three kinds of nano-ZnO particles were selected to prepare nano-ZnO/SBS composite modified asphalt with different content,and the effects of nano-ZnO particle size and content on the softening point,ductility,penetration and Brinell viscosity of nano-ZnO/SBS composite modified asphalt were studied.The results show that the softening point and Brinell viscosity of nano-ZnO/SBS composite modified asphalt increase with the increase of nano-ZnO content.At the same content,the softening point and Brinell viscosity increase with the increase of particle size,while the ductility and penetration decrease gradually with the increase of nano-ZnO content,but have little effect on them,and the effect of particle size on ductility and penetration is not obvious.The effect of nano-ZnO on the rheological properties of composite modified asphalt was analyzed by dynamic shear rheological test and low-temperature bending beam rheological test.The results show that the complex modulus G~*of nano-ZnO/SBS composite modified asphalt increases with the increase of particle size and content of nano-ZnO.The particle size has a great influence on the high temperature performance of the composite modified asphalt and has little effect on the low temperature performance.In low frequency region(high temperature region),the complex modulus of composite modified asphalt is much higher than that of SBS modified asphalt.In high frequency region(low temperature region),the complex modulus of composite modified asphalt is higher than that of SBS modified asphalt,but the master curve of complex modulus at the end is relatively close,indicating that nano-ZnO not only enhances the high temperature performance of SBS modified asphalt,but also has little effect on its low temperature performance.The temperature scanning of asphalt samples shows that with the increase of the content of nano-ZnO/SBS composite modified asphalt,the slope of G’and G"to temperature increases at first and then decreases,and the sensitivity to temperature decreases.At the same time,with the addition of nano-ZnO,the anti-deformation ability of nano-ZnO/SBS composite modified asphalt is much stronger than that of SBS modified asphalt,and has better anti-rutting ability.The cumulative strain of nano-ZnO/SBS composite modified asphalt is significantly lower than that of SBS modified asphalt with 0 nano-ZnO content,and with the increase of nano-ZnO content,the cumulative strain decreases at first and then increases slightly,which indicates that the addition of nano-ZnO can improve the high temperature deformation resistance of SBS modified asphalt.The steady-state viscous flow curve of the sample was obtained by steady-state viscous flow test at 60℃.The steady-state viscosity of nano-ZnO/SBS composite modified asphalt increases with the increase of nano-ZnO content.The composite modified asphalt increases significantly with the increase of nano-ZnO content.When the content of nano-ZnO is the same,theη0 of composite modified asphalt increases gradually with the increase of nano-ZnO particle size.The S/m value of nano-ZnO/SBS composite modified asphalt increases with the increase of nano-ZnO content,indicating that nano-ZnO makes the low-temperature performance of composite modified asphalt worse,but will not affect its low-temperature classification.The difference of particle size has little effect on it and has no obvious change law.Through storage stability test and fluorescence microscope analysis,it is concluded that with the increase of nano-ZnO content,the segregation of nano-ZnO/SBS composite modified asphalt gradually decreases,the compatibility becomes better,the SBS particles become finer,the volume fraction of SBS phase increases gradually,the network structure becomes more and more obvious,and the interface between SBS phase and asphalt phase becomes more and more blurred,indicating that nano-ZnO promotes the compatibility of SBS phase and asphalt.It can make SBS swell more fully in asphalt.The effects of SBS modified asphalt and nano-ZnO/SBS composite modified asphalt on the road performance of asphalt mixture were compared.The results show that the addition of nano-ZnO has a great influence on its high temperature performance,the dynamic stability increases obviously,and the rutting resistance of SBS modified asphalt is improved.It slightly reduces the cracking resistance of asphalt mixture at low temperature,and basically does not affect the water stability of asphalt mixture. |
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