Research On Aging And Recycling Performance Of SBS Modified Asphalt

Our country's expressway construction have developed so fast in recent years,SBS modified asphalt is widely used in the paving of asphalt pavement due to its good high and low temperature performance.The performance of asphalt pavement decreases because of aging in the long-term use process.Asphalt pavement renovation and maintenance process produce large amounts of reclaimed asphalt pavement material(RAP).Recycling of the RAP is of great significance to reduce environmental pollution and to avoid wasting of materials.Recycling of aged asphalt is key to the recycling of RAP.Aged SBS modified asphalt was obtained by TFOT test of SBS modified asphalt was prepared in laboratory to simulated the actual aging situation of asphalt pavement in this paper.Three kinds of commonly used rejuvenating agent H,S,G were selected for the recycling of aged SBS modified asphalt.Penetration,softening point,viscosity,ductility,toughness and tenacity of aged SBS modified asphalt and recycled SBS modified asphalt were tested.The microscopic phase and distribution of SBS was analyzed by fluorescence microscope before and after recycling of aged SBS modified asphalt and rejuvenating agent S was selected for the recycling of aged asphalt mixture.The results showed that the aging of SBS modified asphalt is different from that of base asphalt,and SBS modified asphalt has a better anti-aging ability.The performance of recycled asphalt which was obtained under the optimum rejuvenating agent dose can meet the standard.Determination of optimum asphalt content,mixing ratio design and testing and other steps were systematically studied by Marshall Design Method.Considering the variability of RAP in the plant,aged asphalt mixture was obtained by mixing aged asphalt and aggregates method,recycled asphalt mixture was prepared by adding rejuvenating agent to the aged asphalt mixture and fresh asphalt mixture was obtained by mixing new asphalt and aggregates.Same AC-13 gradation was selected for these three kinds of asphalt mixtures.Different time of oven keeping test of recycled asphalt mixture was conducted.Marshall stability test,rutting test,splitting test,low temperature bending test and residual stability test were conducted to compare the road performance of these three kinds of asphalt mixture.The results showed that the 15? splitting strength and low temperature performance of recycled and fresh asphalt mixtures are better than that of aged asphalt mixture while the high temperature performance is at the opposite.With the extension of oven keeping time,high temperature performance of recycled asphalt mixture decreased while 15? splitting strength and low temperature performance were improved and 15? splitting strength of recycled asphalt mixtures reach 27.74 KN when the keeping time is 4h.Marshall residual stability was not sensitive to reflect the effect of oven keeping time on water stability of recycled asphalt mixture in this paper.After 2 hours' keeping time when the temperature is 150?,the road performance of recycled asphalt mixtures reach the level of fresh asphalt mixtures.