Study On Road Performance Of Hot In-Plant Recycled Porous Asphalt Mixture

With the background of the imminent need to repair the first batch of porous asphalt pavements constructed in China,it is necessary to conduct in-depth research on the recycling technology of porous asphalt pavements.Higher activation and repair requirements must be proposed for the adhesion performance between high-viscosity asphalt and aggregates,in order to achieve the higher goal of synchronously restoring the surface function and durability of the porous asphalt pavements through regeneration,and to provide new avenues for promoting sustainable development and the strategy of building a strong transportation nation and achieving the "dual carbon" target.This study firstly developed targeted composite rejuvenators for the adhesion recovery needs of aged high-viscosity asphalt(HVA),further enhancing the matrix material’s viscosityincreasing effect through physical blending and copolymer grafting of the surface functional groups of rosin resin(RR).Three types of composite rejuvenators(REJ-OR,REJ-DA,and REJGC)with adhesion recovery as the goal were prepared using different synthesis methods,and the impact of different types and dosages of rejuvenators on the basic physical properties of the regenerated high-viscosity asphalt was determined.The research showed that all types of regenerators can effectively restore the technical performance of aged HVA to meet specifications.REJ-OR and REJ-DA can improve the high-temperature performance of recycled HVA,but have a certain impact on its low-temperature performance.The addition of REJ-GC improves the low-temperature performance of the recycled HVA,but reduces its hightemperature performance.Secondly,based on physical and chemical experiments,the mechanism of composite rejuvenators in restoring adhesion force of aging HVA was explored from macroscopic to microscopic perspectives.The research shows that three types of composite rejuvenators with high dosage(≥8%)can effectively restore the adhesion force of aging HVA among which REJGC has the best restoration effect.Recycled asphalt using composite rejuvenators has smaller total heat absorption,and Tg further moves to lower temperatures,and new viscosity-enhancing functional groups(C-O)appear in recycled HVA.The composite rejuvenators effectively improve the micro adhesion force of aging HVA,and the recycled HVA surface shows concaveconvex structures(REJ-N,REJ-GC)and grooved structures(REJ-OR,REJ-DA),which are more conducive to adhesion between asphalt and aggregates.There is a high linear correlation between the macroscopic adhesion strength of recycled HVA and the C-O functional group index and micro adhesion force.Then,the rheological properties of the recycled HVA prepared with different types and dosages of composite rejuvenators were studied through frequency sweep(TFS)tests,multiple stress creep-recovery(MSCR)tests,and bending beam rheological(BBR)tests.The results showed that the type and dosage of the rejuvenators significantly affected the rheological properties of the regenerated high-viscosity asphalt.Compared with the aged HVA,the hightemperature performance of the recycled HVA with composite rejuvenators decreased,while the low-temperature performance and elastic recovery ability increased.The effect of the dosage of different types of rejuvenators on the rheological properties of the recycled HVA was different.When using REJ-OR and REJ-GC,the high-temperature performance of recycled HVA decreased with the increase of rejuvenator dosage,while using REJ-OR increased the high-temperature performance of recycled HVA with the increase of rejuvenator dosage.When using REJ-OR and REJ-DA,the low-temperature performance of recycled HVA showed a trend of first increasing and then decreasing with the increase of rejuvenator dosage.When using REJ-GC rejuvenator,the low-temperature performance of recycled HVA continued to increase with the increase of rejuvenator dosage.Finally,the effects of different RAP and REJ-OR dosages on the rutting resistance,lowtemperature cracking resistance,and water stability of the recycled porous asphalt mixture were investigated.The results showed that the high-temperature stability of the recycled porous asphalt mixture increased with the increase of RAP dosage,and its high-temperature stability significantly improved,but the low-temperature performance was worse.The addition of 15%RAP improved the water stability of recycled porous asphalt mixture,but when the RAP dosage reached 30%,the water stability decreased.When the REJ-OR dosage was low(≤8%),it could effectively improve the high-temperature performance,low-temperature performance,and water stability,but further increasing the REJ-OR dosage had an adverse effect on the road performance of recycled porous asphalt mixture.