Study On Performance Of Different Vulcanized Crumb Rubber Modified Asphalt

Crumb Rubber Modified Asphalt was made by incorporating a certain dose of vulcanized rubber into the matrix asphalt, then mixed and sheared the mixture for some time at high temperature. Waste crumb rubber is the powder material made from ground waste rubber products; the waste rubber ingredients are different if waste rubber products are from different sources. The modified effect on matrix asphalt depends on the type, mesh and content of crumb rubber.The study selected respectively heavy truck tire powder, small truck tire powder, agricultural vehicles tire powder, powder fetal crown, the sole tire and hose rubber powder from manufacturers of Shandong and Hubei Province, and considered the specifications of 60 mesh and 80 mesh as well as some doses of 16% , 20% and 24% ,then fabricated 30 kinds of crumb rubber modified asphalt by shearing the mixture for an hour at 190℃with a blending speed of 700 r/min. The study selected penetration, softening point, ductility, penetration index, equivalent softening point, equivalent brittle point as well as plastic temperature range as basic road performance indexes, then analyzed the effect of crumb rubber types, crumb rubber content and crumb rubber size on the above indexes. The results showed that the change of crumb rubber size could change the above indexes; The modified effect of heavy truck tire powder, small truck tires powder and fetal crown powder was better than the other three powders while fetal crown modifiers was obviously better than the other five crumb rubber modifiers; The higher content of crumb rubber could significantly change these basic performance indexes of road pavement.The study selected heavy truck tire powder, small truck tire powder and agricultural vehicles tire powder respectively and considered the specifications of 60 mesh and 80 mesh as well as three crumb rubber contents of 5%,10%,15%,20% and 25%, then fabricated 15 kinds of crumb rubber modified asphalt with the same process. The study selected viscosities at 60℃,135℃,175℃and viscosity-temperature index as indexes, then analyzed the effect of crumb rubber types and crumb rubber content on viscosity and viscosity-temperature index. The results showed that the change in crumb rubber type had little effect on viscosity and viscosity-temperature index, and TG modifier had a greater improvement on viscosity and thermal performance of matrix asphalt than DK and XK ; With the increase of crumb rubber content ,viscosity increased and VTS decreased, the increase (decrease) curve had a turning point at a specific crumb rubber content; To possess the best modified effect, we suggested that the content of crumb rubber was 10% to 20% ; for three kinds of modified asphalt with a crumb rubber content of 10% above, mixing temperature, paving temperature and compacting temperature of the modified asphalt mixture should be raised.The study selected heavy truck tire powder, small truck tire powder and agricultural vehicles tire powder respectively and considered the specifications of 60 mesh as well as 5%, 10%, 15% and 20% crumb rubber content, then fabricated 12 kinds of crumb rubber modified asphalt with the same process above. The study selected stiffness modulus S and relaxation slope m as indexes, then analyzed the effect of crumb rubber types and crumb rubber content on low-temperature crack resistance of crumb rubber modified asphalt.The results showed that low-temperature crack resistance of TG modified asphalt was the best, the relationship between m value and the types of crumb rubber demonstrated discrete, with the increase of crumb rubber content, the value of stiffness modulus S decreased, the value of relaxation rate m decreased, but the regularity of m value and crumb rubber content was not obvious while crumb rubber content had little effect on m value.The results showed that elastic recovery ratio of TG modified asphalt was the best, the relationship between elastic recovery ratio and the types of crumb rubber demonstrated discrete, with the increase of crumb rubber content.