Research On Preparation And Performance Of Crumb Rubber-PE-SBS Composite Modified Asphalt

In highway engineering,waste tire crumb rubber is used as asphalt modifier to prepare crumb rubber modified asphalt(CRMA),which can effectively improve the asphalt properties.Some experts and scholars proposed the SBS(Styrene-butadienestyrene,SBS)and crumb rubber(Crumb Rubber,CR)two blended modified to prepare CR-SBS modified asphalt(Crumb Rubber-SBS Modified Asphalt,CR-SBSMA),the addition of crumb rubber to solve the problem of high cost of SBS,but also to achieve the same road performance,but the storage stability of this asphalt is not good.With the increasing call for high-viscosity PE modifiers in asphalt materials research.Experts and scholars try to modify it with CR or SBS two doping,the modified stability improved significantly,but the low temperature performance is not goodIn response to the current situation that the two roles of CR,SBS and PE are all deficient,but the advantages are complementary.In this paper,based on the orthogonal test method,CR-PE-SBS modified asphalt(CR-PE-SBSMA)was prepared.The high and low temperature,temperature-sensitive,viscosity,rheological properties,storage stability and aging properties were compared with those of CRMA and CR-SBSMA on the basis of a better preparation scheme,and micro-mechanical analysis and road-use properties of the mixes were carried out.The main studies are as follows.(1)Based on the orthogonal test method,CR doping,CR particle size,SBS doping and PE doping,shear temperature,shear time and shear rate were selected as independent variables,and a total of 18 high-speed shear preparation schemes were designed with 7 factors and 3 levels,and the three main indexes and Brinell viscosity were used as performance indexes.The CR-PE-SBSMA preparation scheme was preferred by extreme difference and ANOVA as follows: CR particle size 40 mesh,15%doping,PE doping 1%,SBS doping 4.0%,shearing temperature 190°C,rate adjusted to 5500 r/min,and shearing 60 min.(2)CR-PE-SBSMA samples were prepared,high and low temperature,temperature-sensitive,rheological,storage stability and aging tests were conducted,and the test results were compared and analyzed with CRMA and CR-SBSMA.The results show that the composite modified asphalt high temperature performance,temperature-sensitive performance and storage stability performance has significantly improved,low temperature performance slightly improved,no significant improvement in aging performance,viscosity is larger,the recommended mixing temperature is 183.6 ℃.(3)Based on the analysis of the microstructure and functional group changes of CR-PE-SBSMA by scanning electron microscopy(SEM)and infrared spectroscopy(FTIR),it is concluded that in CR-PE-SBSMA,CR,PE and SBS are miscible with the matrix asphalt,the process does not produce new functional groups,mainly physical effects,some of the characteristic peaks in CR and SBS are obviously characterized in the composite modified asphalt.The addition of PE is mainly manifested in the increase of the relative content of saturated hydrocarbons,which improves the stability of the composite modified asphalt,the strong combination of the three,forming a stable structural system of the composite modified asphalt,improving the compatibility of the mastic powder with the matrix asphalt,while the modifier is dispersed and miscible,the asphalt surface pits and gully-like distribution of uniform,to ensure adequate bonding with the mineral.(4)For the matrix asphalt,CRMA,SBSMA,CR-SBSMA and CR-PE-SBSMA five asphalt,design AC-13 grade,molding mix test blocks,by comparing high temperature,low temperature,water stability performance and fatigue performance test results concluded that the composite modified asphalt mixture high temperature performance,water stability performance and fatigue performance advantages,low temperature performance also slightly improved.