Experimental Study On Pavement Performance Of Warm Mix Asphalt Modified By Polyester Fiber

In recent years,energy consumption has multiplied daily,and the ecological environment has become increasingly severe.Hot mix asphalt(HMA)which requires high temperature for the process of mixing,paving and compaction,consumes a lot of energy,and emits dust and toxic gases.As a resource-saving and environment-friendly material,Warm Mix Asphalt(WMA)was used to achieve energy saving and emission reduction by controlling temperature.However,due to the defects of the asphalt pavement itself,the complexity of the climatic environment,the increase in the traffic volume and the proportion of overloaded trucks,the problems of asphalt pavements are increasing,ruts,pits and short service life are frequent.How to ensure excellent performance,energy saving and emission reduction has become an urgent problem to be solved.This paper relies on the research topic of “Evaluation Methods for Energy-Saving and Emission Reduction of Asphalt Pavement and Its Application in Municipal Road Construction”(Project No.LGCG2016109)of the Construction and Public Works Bureau of Longgang District,Shenzhen.Through Marshall test,water-immersed Marshall test,high temperature rutting test,four-point bending fatigue test,the properties of warm mix asphalt modified by polyester fiber were tested by selecting four contents(0%,0.1%,0.25%,0.4%)and four lengths(0mm,3mm,6mm,12mm).Finally,the optimum polyester fiber content and length were determined.The research content and main conclusions are summarized as follows:(1)Performance evaluation of warm mix asphalt with different warm additive contents.The penetration,softening point,ductility and adhesion of warm mix asphalt with different EC130 contents were tested experimentally.The test results show that with the increase of EC130 content,sensitive-temperature property of warm-mix bitumen improved,the high-temperature performance slightly increased,the low-temperature performance continued to decrease.and the optimum content of the warm additive is 6% of the mass of the asphalt.(2)The design of mix proportion of warm mix asphalt modified by polyester fiber.The Marshall test and the asphalt film thickness calculation were used to determine the optimum asphalt content of the mixture under different fiber contents and lengthes.The test results showed that the asphalt film thickness on the surface of the stone is 6.506 μm,and the asphalt film thickness on the fiber surface is 9.102 μm.Compared with stone,polyester fiber has stronger adsorption effect on asphalt.(3)Study on compaction performance of WMA under different fiber contents and lengthes.The Marshall test was used to determine volume indes,such as the bulk volume relative density,the porosity,voids in mineral aggregate,VFA under different fiber contents and lengthes.The test results show that the addition of polyester fiber leads to the decrease of the bulk volume relative density.with the increase of the polyester fiber content,the void increases first and then decreases.When the fiber content is 0.25%,the closest void ratio is 4%.with the increase of the polyester fiber length,the void increases first and then decreases.When the fiber length is 6mm,the closest void ratio is 4%.(4)Study on moisture susceptibility of WMA under different fiber contents and lengthes.The Marshall test and immersion Marshall Test was used to determine the residual stability under different fiber contents and lengthes.The test results show that with the increase of the polyester fiber content,the residual stability increases first and then decreases.When the fiber content is 0.25%,moisture susceptibility is optimal.with the increase of the polyester fiber length,the residual stability increases.When the fiber length is 12 mm,moisture susceptibility is optimal.(5)Study on high temperature stability of WMA under different fiber contents and lengthes.Rutting test was used to determine the dynamic stability,relative deformation ratio and complex stability index under different fiber contents and lengthes.The test results show that with the increase of the polyester fiber content,the high temperature stability increases first and then decreases.When the fiber content is 0.25%,the high temperature stability is optimal.with the increase of the polyester fiber length,the high temperature stability increases first and then decreases.When the fiber length is 6mm,the high temperature stability is optimal.(6)Study on fatigue property of WMA under different fiber contents and lengthes.The four-point bending fatigue test was used to determine fatigue life and bending stiffness modulus under different fiber contents and lengthes.The test results show that the fatigue life of the mixture under the four fiber contents was: WMA + 0.25%PF > WMA + 0.4%PF > WMA + 0.1%PF > WMA.The fatigue life of the mixture under four fiber lengths was: WMA+ 6PF > WMA + 12 PF > WMA + 3%PF > WMA.Considering comprehensively,the optimum polyester fiber content was determined to be 0.25%,and the optimum polyester fiber length was 6 mm.