Study On The Performances Evaluation Of Warm-Recycled Mix Asphalt

Warm-Recycled Mix Asphalt (WRMA) is a new type of mixture that can not only reduce the mixing temperature and exhausting gas emissions but also use some reclaimed asphalt pavement, (RAP). It can be mixed, compacted and paved at a relatively lower temperature because of the temperature reduceing agent. Therefore, researching and developing the technology of WRMA will have important significances in the context of energy saving and environmental protection.Two temperature reducing agents LTS and LTR are selected to do the the warm asphalt mixture evaluation and comparison, like the compaction characteristics and pavement performance at different RAP dosages.The binders with LTS and LTR were prepared by high-speed mill, and the influence of additives were evaluated. The penetration test, the softening point test, the ductility test and the brookfield viscosity test for asphalt were conducted to investigate the impact of additives on the properties of asphalt. The research indicated that the additives can reduce the viscosity of base bitumen at high temperature. LTS affects bitumen's other properties obviously while LTR has minimal impact.The volume parameter of WRMA was studied with different RAP contents (0%, 15%, 30%, 45% and 60%) and compaction temperatures (140℃, 130℃, 120℃, 110℃and 100℃), respectively. The research indicated that when the compaction temperatures decreased, VV of asphalt mixtures increased in the same RAP contents. When the RAP contents increased, VV of asphalt mixtures decreased in the same compaction temperatures. The temperature of mixing and compaction of WRMA could be decreased by 20℃and 30℃when RAP contents is 0%. When RAP content was 60%, the temperature of mixing and compaction was equal to HMA in order to ensure the pavement performance.The pavement performances of WRMA were compared and evaluated by means of Mashall test, rutting test, bending-beam test at low temperature, immersion mashall test, frost thawing and splitting test and crooked fatigue test.Recycling agent was used to improve the low temperature resistance and fatigue resistance when RAP contents were 45% and 60%. The pavement performance restored after at the dosage of 8%.It is concluded that at the RAP ratio of less than 30%, the temperature reduction of 20~30℃can be achieved. Nevertheless, when the RAP ratio is over 45%, conventional handling and application temperature is recommanded to WRMA.