Rheological property investigations for polymer and polyphosphoric acid modified asphalt binders at high temperatures Feipeng Xiao a,⇑ , Serji Amirkhanian b , Hainian Wang c , Peiwen Hao c a Key Laboratory of Road and Traffic Engineering of the Ministry of Education, Tongji University, Shanghai, 201804, China b Department of Civil, Construction, and Environmental Engineering, University of Alabama, Tuscaloosa, AL 35487, USA c School of Highway, Chang’an University, Xi’an, China highlights  Rheology on SBS and three alternative binders with/without PPA was studied.  Two base asphalt binders, four polymers, and one PPA were used to produce binders.  Viscosity, G  /sin d, amplitude and frequency sweep, creep recovery, etc. were tested.  0.5% PPA could reduce by 1.0% the polymer needed to produce the PG 76-22 binder.  Rheology of binders is dependent on polymer type, asphalt source and test temperature. article info Article history: Received 17 February 2014 Received in revised form 3 April 2014 Accepted 4 April 2014 Available online 4 May 2014 Keywords: Polymerized asphalt binder Crumb rubber Polyphosphoric acid Viscosity Fail temperature Amplitude and frequency sweep Relaxation abstract Polymer modified asphalt binders have been used with success in mitigating many major causes of asphalt pavement failures (e.g., permanent deformation, moisture induced damage, fatigue, etc.). The sty- rene butadiene styrene (SBS) is commonly used for producing PG 76-22 binder, but the market was hit with a shortage of butadiene back in late 2009, which affected both supply and cost of PG 76-22 through- out the entire United States. Therefore, some alternative modifiers such as elastomers, plastomers, recy- cled ground tire rubber, sulfur additives, and polyphosphoric acid (PPA) to substitute for SBS in PG 76-22 asphalt binders have been investigated for future applications in the industry. The objective of this study was to investigate the high temperature rheological properties of SBS and three alternative polymer mod- ified binders with/without PPA. Two base asphalt binders (PG 64-22), four polymers, and one PPA were used to produce the modified binders. The tested rheological properties include rotational viscosity, fail temperature, G  /sin d, phase angle, viscometry, amplitude sweep, frequency sweep, creep and creep recovery, and relaxation. The test results indicated that the PG 76-22 binders with two alternative poly- mers had noticeably lower viscosity values compared to SBS modified binders and thus need lower energy for mixing and compaction. In addition, for the binders used in this research work, the utilization of 0.5% PPA could reduce by 1.0% of additional polymer needed to produce the PG 76-22 binder. More- over, the characteristics of viscometry, amplitude sweep, frequency sweep, creep and creep recovery, and relaxation spectrums of all modified binders were generally dependent upon polymer type, asphalt source, and test temperature. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction In many cases, heavy traffic loading and severe weather condi- tions will result in some serious functional damage of asphalt pavements. Therefore, polymers have been incorporated into asphalt binders as a way to mitigate many major causes of asphalt pavement failures, including permanent deformation at high tem- peratures and cracking at low temperatures, as well as some other failures such as fatigue, raveling, and stripping damage for many years [1–3]. These polymer modified asphalt (PMA) binders also have been used with success at many locations of high stress such as interstates, intersections, and airports [4]. The PMA has been commonly used materials in high quality asphalt pavement indus- try in many parts of the United States (US). PMA has proven itself to be an essential element in the paving process. http://dx.doi.org/10.1016/j.conbuildmat.2014.04.082 0950-0618/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +1 864 6504821. E-mail address: fpxiao@gmail.com (F. Xiao). Construction and Building Materials 64 (2014) 316–323 Contents lists available at ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat