Study On The Aging Mechanism And Recycling Technique Of Asphalt

The adoption of asphalt pavement recycling technology has economic benefits, social benefits and environment benefits, and it is in accordance with the present trend toward sustainable development. As massive early constructed highway entering repairs period gradually, the research and use of recycling technology of asphalt pavement materials is necessary. However, asphalt pavement recycling technology in our country is still in initial stage, the basic theory research and the engineering project experience are deficient, especially for the recycling of polymer modified asphalt. Therefore, the aging mechanism of the base asphalt and polymer modified asphalt was analyzed, then a new type of recycling agent was developed and the recycling technique of asphalt and asphalt mixture was investigated in this foundation.Firstly, the extraction method of pavement asphalt was studied systematically. The experiment results showed that the norms methods had the problem of residual filler and solvent. Through the improvement of extraction methods, the influence of extraction process on the properties of asphalt was reduced in the greatest degree, and the reliability of performance evaluation of the old pavement asphalt was enhanced.Secondly, the aging rules and aging mechanism of asphalt under different aged condition was studied with simulation aging experiment, and the correlation between the reclaimed asphalt and indoor aged asphalt was compared. The differences of anti-aging property between base asphalt and polymer modified asphalt was analyzed through the asphalt performance tests. The asphalt aging mechanism was investigated with the chemical analysis methods, such as component analysis, infrared spectroscopy analysis and Gel Permeation Chromatography analysis, revealing the causes of the anti-aging property of polymer modified asphalt surpassing base asphalt.A new recycling agent was developed base on the analysis of asphalt aging principle and asphalt recycling principle. Then the performance of recycling agent was proved, and the optimum dosage of recycling agent was ascertained. The diffusion rules of recycling agent was researched with the stage extraction experiment and rheological experiment. At the same time, for the shortage of evaluation methods of recycling agent, a new test method was invented using the electrical conductivity experiment of the system of asphalt and n-heptane to evaluate the effect of recycling agent. The experiment results of different recycling agent showed that the peptization of recycling agent developed in this paper for the asphaltene is better, and the advantage of this recycling agent was proved from the point of view of asphalt colloid structure.The aged base asphalt and polymer modified asphalt was recycled with new asphalt and recycling agent. Then the performance of recycled asphalt was discussed particularly and the aging mechanism of recycled asphalt was analyzed from the microstructure angle. The anti-aging performance of recycled asphalt was investigated and the life estimation method of recycled asphalt was created based on Arrhenius chart.Finally, the mixture design method of recycled asphalt mixture was processed, and the impact of the RAP content on the optimum asphalt content was analysed. The compaction characters of recycled asphalt mixtures was investigated by gyratory compaction test, and the mixing and compaction temperature was determined. The performance of recycled asphalt mixture, including high temperature performance, low temperature performance, moisture sensitivity and durability performance, were proved as good as the new asphalt mixture.