Design Method And Performance Of Hot Recycling SBS Modified Asphalt Mixture

Asphalt pavement recycling technology can reuse recycling asphalt pavement(RAP), to save resource, protect the environment and reduce investment. Asphalt pavement recycling technology can date back to the 1915 in the United States. By the end of 20th century, asphalt pavement recycling technology has reached a high level in the US. China’large-scale road construction began in the late 1980s, and now China is still in a period of massive new construction. This technology is still at starting stage currently. As more and more asphalt pavements get into the period of maintenance and repair, it is extremely urgent to research and popularize asphalt pavement recycling technology.This paper relies on the project of hot in-place recycling in Hengyang to Dapu expressway which is in Hunan Province and the design method and performance of hot recycled asphalt mixture was carried out. Aging principle and asphalt recycling principle of polymer modified asphalt were also discussed in this paper. The result shows that: aging principle of polymer modified asphalt is different from that of base asphalt. Anti-aging property of polymer modified asphalt is more complicated and surpassesed than that of base asphalt. Then the performance of recycling agent was proved, and the optimum dosage of recycling agent was ascertained.Optimum asphalt content of hot recycled asphalt mixture of different RAP content was ascertained by Marshal design method. The performance of recycled asphalt mixture, including high temperature performance, low temperature performance, moisture sensitivity and structure design parameters, were proved as good as the new asphalt mixture. Moisture sensitivity and high temperature performance are better than those of new asphalt mixture. Remnants stability, the freezing-thawing split tensile strength rate (TSR) increase with the increment of RAP content, but changes little; Dynamic stability (DS) increase from 6 040 s/mm to 9 177 s/mm with the increment of RAP content form 25% to 85%, that proving recycled asphalt mixture’s high temperature performance is enhanced. Recycled asphalt mixture’s flexural-tensile strain and strength decrease with the increment of RAP content, which are still above the requirements of standard and criteria. Compressive resilient modulus, compressive strength of recycled asphalt mixture increases linearly with the increment of RAP content. Compressive strength in 20℃increase from 6.39 MPa to 7.63MPa, and that in 15℃increase from 8.01 MPa to 9.03MPa with the increment of RAP content from 25% to 85%. Compressive resilient modulus of recycled asphalt mixture is larger than that of standard and criteria. Compressive resilient modulus in 20℃increase from 2 650 MPa to 3 029MPa, and that in 15℃increase from 3 213 MPa to 3 675MPa with the increment of RAP content from 25% to 85%. Split tensile strength, failure stiffness modulus increase linearly with the increment of RAP content. Split tensile strength increase from 1.965 MPa to 2.841MPa, failure stiffness modulus increase from 522.52 MPa to 907.38MPa, failure tensile strain decrease from 6 950μεto 5 789με, with the increment of RAP content from 25% to 85%. Anti-cracking property of recycled asphalt mixture is worse than that of new asphalt mixture.