Investigating effects of ethylene vinyl acetate and gilsonite modifiers upon performance of base bitumen using Superpave tests methodology Mahmoud Ameri a,b,⇑,1 , Ahmad Mansourian b , Amir Hossein Sheikhmotevali a a School of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran 16846, Iran b Transportation Research Institute, Iran University of Science and Technology, Tehran, Iran highlights " Addition of EVA or Gilsonite to base bitumen improve base bitumen rutting resistance. " Fatigue resistance of EVA-modified bitumens is higher than base bitumen. " Fatigue resistance of gilsonite-modified bitumens is less than base bitumen. " Addition of gilsonite decreases low temperature performance of base bitumen. " Addition of EVA of up to 4% improves low temperature performance of base bitumen. article info Article history: Received 15 January 2012 Received in revised form 19 March 2012 Accepted 25 April 2012 Available online 31 July 2012 Keywords: EVA Gilsonite Superpave BBR DSR RV abstract In this research study, relative performance of a series of ethylene vinyl acetate (EVA) and gilsonite mod- ified bitumens were evaluated in terms of three main distress modes of flexible pavement namely rutting, fatigue damage and low temperature cracking. Seven modified and unmodified bitumens were tested and characterized in accordance with the Superpave performance criteria. The experimental tests performed were dynamic shear rheometer (DSR), bending beam rheometer (BBR) and rotational viscosity (RV). DSR test results for rutting showed that addition of EVA and gilsonite increase the rutting parameter (G / / Sin(d)) of the modified bitumens relative to the base bitumen. DSR fatigue test results showed that addi- tion of EVA decreases the fatigue parameter (G / Sin(d)) of modified bitumens while addition of gilsonite increases the fatigue parameter of modified bitumens. BBR test results showed that addition of EVA decreases the creep stiffness (S-value) of modified bitumens while addition of gilsonite increases the creep stiffness of modified bitumens. Moreover, the addition of 2% and 4% EVA increase the m-value of modified bitumens while addition of gilsonite decreases the m-value of modified bitumens. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction A careful balance of binder properties is generally required to alleviate one mode of asphalt mixture distress without aggravating other modes, such as the use of a harder bitumen to alleviate rut- ting without aggravating fatigue cracking [1]. To this end, novel binders with improved rheological characteristics are continuously being developed [1]. The best known form of this binder improve- ment is by means of polymer modification, traditionally used to improve the temperature susceptibility of bitumen by increasing binder stiffness at high service temperatures and reducing stiffness at low service temperatures [2]. The benefits of using modified bit- umens in asphalt mixture production are thoroughly investigated by Al-Hadidy and Yi-qiu [3]. Their comprehensive laboratory tests investigation of rutting and fatigue resistance of asphalt mixtures produced with modified and unmodified bitumens indicate the superior rutting and fatigue performance of asphalt mixtures pre- pared with modified bitumens. In general, polymer modified bitu- mens (PMBs) improve resistance to permanent deformation and fatigue cracking [1]. The polymers that are used for bitumen modification can be di- vided into two broad categories known as plastomers and elasto- mers [1,4]. Plastomers tend to modify bitumen by forming a tough, rigid, three-dimensional network within the binder to resist deformation, while elastomers have a characteristically high elas- tic response and, therefore, resist permanent deformation by stretching and recovering their initial shape [1,4]. 0950-0618/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.conbuildmat.2012.04.137 ⇑ Corresponding author at: School of Civil Engineering, Iran University of Science and Technology, Narmak, Tehran 16846, Iran. Tel.: +98 2177240399; fax: +98 2177240398. E-mail address: ameri@iust.ac.ir (M. Ameri). 1 President of Transportation Research Institute and Head of Center of Excellence of PMS, Transportation and Safety. Construction and Building Materials 36 (2012) 1001–1007 Contents lists available at SciVerse ScienceDirect Construction and Building Materials journal homepage: www.elsevier.com/locate/conbuildmat