The Mixing Mechanism And Experimental Study Of Crumb Rubber Modified Asphalt

With the improvement of economic living standards， the car ownershipcontinues to rise， a variety of high-grade highways are developed rapidly. People alsoput forward higher requirements for ride comfort. On the other hand， large amountsof waste tires have been produced with the increase of the number of cars. At thisstage， recovery utilization rate of waste tire is not high， resulting seriousenvironmental pollution. Made waste tire into rubber power， then added to asphalt，not only can enhance the waste tire utilization， but also can improve the pavementperformance of asphalt. It is the research topics of many scholars.In this paper， wet process was used to prepare rubber modified asphalt.Equivalent softening point T800and equivalent brittle point T1.2were used to evaluatehigh and low temperature performance of modified asphalt. The main work is asfollows:(1)Rubber modified asphalt formula has been optimized though orthogonal testmethod. Gray relational analysis and in weighted composite score were used to processthe experimental data， obtained objective and reliable experimental program.(2)The effects of the crumb rubber content, crumb rubber fineness, crumb rubbertypes, shear conditions and aromatic oil content on the three indicators（25℃penetration，softening point，5℃ductility）were analyzed comprehensively. And theeffects of crumb rubber content and crumb rubber fineness on equivalent softeningpoint T800and equivalent brittle point T1.2were analyzed.(3)Because of the special using environment of tunnel， which is relatively closeand humid， recerched the flame retardant and flame retardant mechanism ofpavement asphalt. In this paper， based on the obtained optimum experimental program， the flame retardant effect of flame retardant under different types anddifferent dosage has been studied. Experimental results show that Dimethyl silicone oil,DBDPE and zinc borate used in conjunction with great flame-retardant effect.Thedimethyl silicone oil can improve the performance of the asphalt. Zinc borate has greatsmoke suppression.(4) The molecular structure of asphalt and crumb rubber is analyzed. It found thatthese two substances have strong inert， generating minimal chemical reactions. Thestructure of the aromatic oil is similar to the structure of light oil in the asphalt. Andswelling effect of the rubber powder is the result of absorbing light oil in asphalt. Sothe adding of aromatic oil promotes the mixture of crumb rubber and asphalt to acertain extent. Scanning electron microscopy of rubber modified asphalt cross-sectionis observed.Further validates the mixing mechanism between crumb rubber and asphaltby analysis the state of crumb rubber in asphalt.The results obtained from the experient meet the requirements of China’s polymermodified asphalt standard. Its perfoemance is much better than asphalt. The fiameretardant properties of modified asphalt reached to gradeⅠ.