Study On Factors Affecting Fatigue Performance Of High RAP Content Thermal Recycled Asphalt Mixture

Asphalt pavement occupies a large proportion in northern China.Its service life is declining year by year due to various loads and external factors,resulting in a large amount of waste asphalt mixture.These waste asphalt mixtures are non-degradable,resulting in a large number of The loss of petroleum resources has seriously damaged the ecological environment.The relevant regulations for the amount of RAP(Recycled Asphalt Mixture)materials in China are 20%～30%.To meet the sustainable development strategy of road construction,improve economic efficiency and environmental protection efficiency,and achieve energy saving of road pavement.The use of recycled asphalt mixture with high-volume RAP material has become a trend.Based on the typical cold and arid climate conditions in Hohhot,the paper analyzes the influence of temperature,frequency and strain factor on the fatigue performance of recycled asphalt mixture in this area.Firstly,it analyzes the local old material gradation and asphalt content,and The old asphalt is tested by indicators to select the best regenerant type and dosage suitable for the cold and arid area.The reclaimed asphalt mixture under different RAP materials is designed for gradation,and then the recycled asphalt mixture is mixed with different RAP materials.The road performance of the material was studied,and the optimal RAP material content suitable for the climatic characteristics of the cold and arid area was selected.The results showed that when the regenerant content was 10%,the recycled asphalt mixture of 50%RAP material was in line with the region.Use the standard.Four-point beam fatigue test was used to test the fatigue of different temperature,frequency and strain of recycled asphalt mixture and fresh asphalt mixture.The fatigue test results of two asphalt mixtures were compared and analyzed.Fatigue equation of factor and temperature factor;then the fatigue limit was calculated by the fatigue equation based on temperature and frequency,and the temperature and frequency were compared to the fatigue limit of two asphalt mixtures.The test results show that:(1)The recycled asphalt mixture with high content of RAP material has better fatigue performance than the fresh asphalt mixture;(2)temperature,frequency and strain have significant influence on the fatigue performance of asphalt mixture.The higher the temperature,the better the fatigue performance of the two mixtures;the fatigue life of the mixture will decrease with the increase of strain or frequency;(3)The fatigue limit of reclaimed asphalt mixture with high RAP content at different temperatures and frequencies is better than that of fresh asphalt mixture.