Nonrecoverable Behavior of Polymer Modified and Reclaimed Asphalt Pavement Modified Binder under Different Multiple Stress Creep Recovery Tests

Abstract

Chinese transportation agencies usually use the styrene–butadiene–styrene (SBS) modified binder and rejuvenators when applying higher reclaimed asphalt pavement (RAP) in surface courses. However, the rutting performance of RAP binder containing SBS binder and rejuvenators remains a problem. In order to better evaluate the rutting performance of asphalt binder, recently, a multiple stress creep recovery (MSCR) test (AASHTO T 350) was proposed and approved. This paper critically reviewed the AASHTO T 350 test method and AASHTO M 332 specification by carrying out a series of MSCR tests. A total of 18 types of SBS modified and modified RAP binders were tested. The effect of a rejuvenator on the rutting performance was analyzed. Three different MSCR tests were conducted considering different stress levels and creep recovery cycles, including test conditions of AASHTO T 350. The results indicated that AASHTO T 350 can grade the binders based on the nonrecoverable creep compliance and stress sensitivity parameters. Since SBS modified binders always have lower Jnr values at lower stress levels, higher stress levels and more creep recovery cycles are recommended to better evaluate the rutting resistance of binder. The addition of RAP decreased the Jnr values while the addition of rejuvenator had the opposite effect. The added SBS modified binder and rejuvenator have a negligible effect on the percentage recovery. It is suggested that a suitable rejuvenator dosage and virgin binder type should be chosen carefully to guarantee the rutting performance of RAP binder.