Research On Properties And Mechanism Of Crumb Rubber/SBS Composite High-Viscosity Modified Asphalt

In recent years,the national automobile manufacturing industry has developed vigorously,and the annual production of waste wheels has reached hundreds of millions.The increasing "black pollution" runs counter to the ecological and environmental protection policies vigorously promoted by the state.In recent years,the use of crumb rubber for asphalt modification has become a mainstream in the field of road engineering,but because of the powder of its poor compatibility with asphalt,easy generation segregation,which makes the crumb rubber asphalt on the storage,production,transportation and construction is convenient,and delay the efficiency of road paving,finally these shortcomings will in the future road of long-term service gradually amplifier,At the macroscopic level,the performance of road is significantly reduced,which is also the main reason for the slow application of crumb rubber asphalt pavement at home and abroad.Relevant scholars proposed to combine the most widely used SBS modifier with crumb rubber to further reduce the use cost on the premise of environmental protection.In this paper,on the basis of summarizing the domestic and foreign research,the essence of crumb rubber asphalt was grasped from the reaction behavior of crumb rubber and asphalt,and the conventional properties and rheological properties of crumb rubber /SBS composite modified asphalt were studied from the macroscopic mechanical properties,providing a new perspective for understanding the performance of crumb rubber /SBS composite modified asphalt.Firstly,the reaction behavior of crumb rubber and asphalt under different temperature was studied,and the conventional properties,rheological properties and modification mechanism of crumb rubber asphalt were comprehensively evaluated by controlling different processing temperature and processing time.At the micro level,it is speculated that physical swelling reaction mainly takes place at lower processing temperature and time.With the increase of temperature and time,chemical reaction gradually takes place between crumb rubber and asphalt,accompanied by desulfurization,aging,desaromatization and aromatization,and the reaction reaches dynamic equilibrium at 240℃.At the macro level,the influence of processing temperature on the cracking degree of crumb rubber is higher than that of processing time.In terms of the improvement of high temperature performance,it decreases with the increase of processing temperature on the whole,and the performance changes are different with the increase of processing time.When the temperature is low,the high temperature performance is improved,and when the temperature is high,the high temperature performance decreases first and then increases.It is necessary to consider the influence of high temperature cracking of crumb rubber and high temperature aging of asphalt on conventional properties.In terms of fatigue performance,high temperature cracking at low strain level will seriously affect the fatigue resistance of asphalt,but at high stress level,the cracking degree of crumb rubber has little effect on the fatigue performance of asphalt.In terms of low temperature performance,the higher the cracking degree of crumb rubber,the greater its stiffness modulus,and the better the relaxation performance of crumb rubber asphalt.Second,for optimizing the surface of high sticky modified asphalt road suitable for drainage,through the analysis of conventional performance and rheology level,it is concluded that crumb rubber/SBS composite modified asphalt and high sticky particles composite modified asphalt has excellent high and low temperature performance,and high sticky particles composite heat storage stability and fatigue performance of modified asphalt is very outstanding,The results show that the high viscosity composite modified asphalt prepared by high viscosity particles has good workability and stability.Thirdly,the mechanism of crumb rubber /SBS composite high viscosity modified asphalt was studied.Infrared spectrum analysis showed that physical swelling reaction mainly occurred in the preparation process of the composite modified asphalt with high viscosity particles.Fluorescence microscopic analysis showed that the crumb rubber and SBS in the high viscosity particles were more evenly distributed in the asphalt phase.The continuous structure formed by SBS wraps the rubber particles with uniform shear and forms a three-dimensional network system,which shows excellent high and low temperature performance,thermal storage performance and fatigue performance at the macro level.Finally,according to the design specification of drainage asphalt mixture,the PAC-13 asphalt mixture with drainage performance is designed,and the composite modified asphalt with high viscosity particles and SBS modified asphalt with high dosage are used as asphalt binder.The test results show that the road performance of the two is similar,and the grading has good drainage performance.