Study On Performance Of Rubber Powder/SBS Composite Modified Asphalt And Mixture

The increase in traffic volume,heavy load,and overload,the frequent occurrence of extreme climate and other factors lead to higher requirements for the performance of Expressway Asphalt Pavement in China.SBS modified asphalt(SBSMA)and rubber asphalt(CRMA)are two kinds of commonly used asphalt materials,but there are many problems in the actual application process,and the rubber powder/SBS composite modified asphalt technology can combine the advantages of rubber powder and SBS two modifiers,reduce the production cost of modified asphalt,and use the waste rubber powder resources,which is a technology with both economic and social benefits.However,there are still some problems in the preparation of CR/SBS composite modified asphalt(CR/SBSMA),such as the difference in preparation technology and the great variation of quality.Under this background,this paper carried out a systematic study on the preparation process,rheological properties and modification mechanism of rubber powder/SBS composite modified asphalt,and verified and compared the road performance of rubber powder / SBS composite modified asphalt mixture.Firstly,from the characteristics of the two modified materials,the influences of feeding mode,development temperature,modifier content and additives on the performance of asphalt are clarified.At the same time,through three major indexes,elastic recovery test,segregation,viscosity,and other macro performance evaluation methods,the influence of modifier content and development time on the macro performance of asphalt is analyzed.Using the method of significance difference analysis,the development time,the amount of modifier and the significance of asphalt macro performance tests were analyzed,and the prediction model was established.Finally,the preparation process and parameters of the rubber powder / SBS composite modified asphalt were determined as follows: first,put SBS,then put rubber powder,and then develop for 3 hours,the development temperature was 180 ± 5 ?,the amount of stabilizer was 2 ‰,the amount of compatibilizer(furfural extraction oil)was 3.0%,and the amount of rubber was 2 ‰ The content of SBS is 2.5-3.5%.Based on the principle of rheology,the multi stress repeated creep recovery test(MSCR)and low temperature bending rheological beam test(BBR)were carried out for the rubber powder / SBS composite modified asphalt.With the strain recovery rate R and the nonrecoverable creep flexibility "Jnr" The high-temperature rheological properties of asphalt at different temperatures were evaluated.It was found that the effect of "heavy load" and "high temperature" on the high-temperature deformation resistance of crumb rubber / SBS composite modified asphalt was similar.The low-temperature rheological properties of asphalt were evaluated by creep stiffness modulus s and creep stiffness change rate M,and the low temperature creep flexibility curve was simulated and analyzed by burgers visco-elastic model,and asphalt was constructed It is found that SBS content has a good correlation with asphalt low-temperature performance,while rubber powder content has a bad correlation with lowtemperature performance.The micro morphology and modification mechanism of the composite modified asphalt was analyzed by SEM and FTIR.The results show that the development time and the number of modifiers have an obvious influence on the micro morphology of the composite modified asphalt.With the increase of development time,the better the SBS network structure in asphalt develops,the better the adhesion with a modifier;with the increase of SBS content,the more stable the SBS rubber powder asphalt three-phase system structure in asphalt;with the increase of rubber powder content,the coagulation and agglomeration of rubber powder particles in asphalt will increase,leading to the increase of viscosity.The modification mechanism of rubber powder / SBS composite modified asphalt is similar to that of SBS modified asphalt and rubber asphalt,that is,the modifier and matrix asphalt are mainly in physical mixing state;with the growth of development time,the degree of an oxidation reaction in matrix asphalt increases gradually;the aromatic content in asphalt decreases gradually,and the swelling of modifier and matrix asphalt is more sufficient.Finally,the ARAC-13 structure is selected to verify and compare the road performance of SBS modified asphalt mixture,rubber asphalt mixture and rubber powder / SBS composite modified asphalt mixture.The results show that the high-temperature performance and water stability of the asphalt mixture can be significantly improved by using rubber powder and SBS composite modified technology,and the low-temperature stability is similar to that of SBS modified asphalt mixture.