Research On High Performance Anti-cracking SMA9.5 Asphalt Mixture

The cracking of the asphalt pavement is the root cause of other diseases on the pavement.There are many reasons for its cracking,of which low-temperature cracking is one of the main reasons for most of the cracks.Improving the low-temperature crack resistance of asphalt mixtures plays an important role in improving the crack resistance of asphalt pavements,enhancing road performance,and extending the service life of the pavement.This article studies and explores effective methods to improve the low-temperature cracking ability of SMA9.5 asphalt mixture for joints from two aspects of improving the performance of asphalt and its mixture.For asphalt,different methods of modifying asphalt are used,that is,adding SBS and nano-zinc oxide modifiers to improve its performance.Atomic force microscope test（AFM）test and bending beam rheological test（BBR）were used to evaluate the micro-morphological characteristics,micro-elastic modulus(E_DMT),macro-bending creep stiffness S and stress relaxation rate m of the modified asphalt Low temperature performance of asphalt.For asphalt mixtures,two different fibers（lignin fibers and basalt fibers）,different fiber additions,and TPS high-viscosity modifiers are added,respectively,through the low-temperature splitting test of the asphalt mixture,and indirect tensile testing.Tension rebound test and low-temperature trabecular bending test,etc.,to study the failure strain and stiffness modulus of asphalt mixtures with different formulations at low temperature to evaluate the low-temperature crack resistance of asphalt mixtures.Finally,from the above-mentioned different formulations of asphalt and asphalt mixtures,the formula with the best performance is selected and combined as the best formulation of the anti-cracking asphalt mixture,and compared with the imported TST elastic material.Research shows:1)With the increase of the SBS content,the number of honeycomb structures in the micro morphology of the asphalt increases and the area decreases.This phenomenon becomes more obvious after adding nano-zinc oxide.The E_DMTof modified asphalt presents a normal distribution.With the increase of SBS content and the addition of nano-zinc oxide,the E_DMTof modified asphalt has a decreasing trend.The results show that these modifiers can obtain smaller creep stiffness and greater stress relaxation rate,and improve the low-temperature performance of the modified asphalt.2)When the content of lignin fiber is 0.5%and the content of basalt fiber is 0.6%,the best low-temperature deformability of asphalt mixtures with different content of lignin and basalt fiber can be obtained,and TPS high-viscosity modification is added.After spraying,especially at 0°C,the low-temperature deformability of the asphalt mixture is reduced.3)The resilience modulus of the basalt fiber group is significantly higher than that of the lignin fiber group and the combination of lignin fiber and TPS,and the resilience modulus of each group at-10°C is affected by the SBS content,nano zinc oxide and fiber The influence of quantity and type is not significant.4)SBS-nano-zinc oxide composite modified asphalt and basalt fiber are used to prepare asphalt mixture,and the trabecular bending test is carried out.The bending tensile failure strain is greater than that of asphalt mixture prepared with ordinary SBS modified asphalt and lignin fiber.Although the low temperature deformation performance of this asphalt mixture is not as good as the imported TST elastic material used in engineering practice,its low temperature performance has been greatly improved compared with ordinary asphalt mixture,and the cost-benefit ratio is far lower than that of TST elastic material.