Polyester Recycled Asphalt Mixture Low Temperature Salt Erosion Crack Resistance

China adheres to the strategy of sustainable development,the practice of green environmental protection development route.In order to solve the environmental problems caused by waste asphalt mixture,the state began to pay attention to the development of asphalt pavement regeneration technology,and recycled asphalt mixture is also being increasingly used in highway construction.Recycled asphalt mixture pavement during the service period,due to the environment,driving load and other external factors,asphalt pavement crack damage,resulting in recycled asphalt mixture road performance is reduced,often can not meet the design and use requirements,of which low temperature cracking is one of the most important reasons,therefore.In order to promote the recycled asphalt mixture more extensive application practice,it is necessary to study the low temperature crack resistance of recycled asphalt mixture.The test prepared the recycled asphalt mixture specimens with RAP content（0%,10%,20%,30%,40%,50%）,the number of freeze-thaws（0,2,4,6,8）and usage environments（clear water,Na Cl:Na₂SO₄=1:2 composite salt solution with a mass fraction of 3.6%）,and set up pre-cracks at the center of the bottom of the specimens to carry out salt erosion test and salt freeze-thaw cycle and erosion coupling test.The SCB test was carried out at-10°C,and the low temperature crack resistance of the recycled asphalt mixture was comprehensively evaluated with peak load,fracture energy,stress strength factor and ultimate deformation as the evaluation index,which provided a theoretical basis for engineering application in central and western.Through experimentation,the following conclusions are obtained after processing the analysis data:（1）According to the three asphalt regeneration mechanisms,the old asphalt is regenerated by adding a regeneration agent,and the three major indicators are used as the evaluation criteria to determine that the optimal content of the regeneration agent is10%.（2）The addition of polyester fiber can significantly improve the crack resistance of recycled asphalt mixture.The peak load and fracture energy increase and then decrease with the increase of polyester fiber content,and the performance of recycled material is optimal when the content of polyester fiber reaches 0.4%.（3）The peak load gradually increases with the increase of RAP content,the fracture energy decreases with the increase of RAP content,when the RAP content is high,the salt erosion resistance of the recycled material can be improved,the low temperature crack resistance of the recycled asphalt mixture with high RAP content fluctuates greatly,and it is recommended that the RAP content is not higher than 30%to control the effect of material variability on the performance of the recycled asphalt mixture.（4）The composite salt solution will deteriorate the low temperature crack resistance of the recycled material.Compared with the specimens soaked in clean water,the peak load and fracture energy of the specimens after the erosion of the composite salt solution are small,indicating that the salt erosion destroys the effective bonding inside the specimens and makes the low-temperature crack resistance of the recycled asphalt mixture worse.（5）In the coupling test of salt freeze-thaw cycle and erosion,the stress intensity factor of the recycled asphalt mixture increased with the increase of RAP content,but the limit deformation gradually decreased,indicating that the stiffness of the recycled material increased with the increase of RAP content,but the plastic deformation ability attenuated.（6）The freeze-thaw cycle attenuates the low temperature crack resistance of the recycled asphalt mixture.With the increase of the number of freeze-thaw times,the stress strength factor and deformation of the recycled asphalt mixture are gradually reduced.With the increase of RAP dosage,the deformation of the recycled asphalt mixture is gradually reduced,and it is recommended to reduce the RAP dosage in the seasonal freeze-thaw area.（7）The coupling effect greatly attenuates the low temperature crack resistance of the recycled asphalt mixture.Under the coupling of salt freeze-thaw cycle and erosion,the stress strength factor and limit deformation of the recycled asphalt mixture gradually decreased with the increase of the number of salt freeze-thaw times,and the reduction range showed a growing trend,and the coupling effect greatly attenuated the low-temperature crack resistance of the recycled asphalt mixture.Figure[38]Table[23]Reference[75]...