Technical Paper ISSN 1997-1400 Int. J. Pavement Res. Technol. 4(3):154-161 Copyright @ Chinese Society of Pavement Engineering 154 International Journal of Pavement Research and Technology Vol.4 No.3 May 2011 Adaptation of Superpave Asphalt Concrete Mix Design Procedure to Jordan Climatic and Traffic Conditions Ibrahim M. Asi 1+ and Yahia Khalayleh 2 ─────────────────────────────────────────────────────── Abstract: Highways in Jordan are typically designed and constructed to last at least 20 years. However, it is not uncommon to see flushing, rutting, and cracking in asphalt pavements well before that period, especially in areas exposed to harsh environmental conditions and heavy traffic loadings. The Superpave (Superior Performance Pavements) system was developed to give highway engineers the tools they need to design asphalt pavements that will perform better under temperature extremes and heavy traffic loads. This research was established to study the possibility of adopting the Superpave mix design procedure in Jordan using prevailing traffic and environmental conditions. In this study, a map showing the different temperature zones available in Jordan was developed. A comparison study was carried out utilizing local materials to design asphalt mixes using both Marshall and Superpave mix design procedures. It was found that the Superpave mix design procedure recommended, for the local environmental and loading conditions, lower asphalt content than that predicted by Marshall mix design procedure. In addition, it was found that using the presently recommended local aggregate gradation for heavy traffic in the Superpave design method gave dust proportion higher than the maximum specified limit by the Superpave procedure. High dust proportion will usually lead to brittleness of the mixes. Therefore, shifting to the Superpave design procedure might help in solving the bleeding problem and some of the distresses common in the local asphalt structures. Key words: Marshall; Performance grading; Superpave; Temperature zoning. ─────────────────────────────────────────────────────── Introduction 12 During the last decades, the Hashemite Kingdom of Jordan (HKJ) experienced a rapid rate of development in many areas. Construction of thousands of kilometers of freeways, urban arterials, and agricultural roads has played an important role in such development. In the last 50 years, Jordan has invested about JD 1 billion in constructing about 8000 km of roads with an approximate construction cost of JD 150,000 (US$180,000) per kilometer. These roads were designed for the anticipated number of traffic load repetitions for a design life of 20 years. Growths in socio-economic and industrial sectors were encouraged and this resulted in the generation of a great deal of city and intercity heavy vehicle transportation. Due to this, and due to the local environmental conditions in the country, a number of segments of these highways experienced high degrees of rutting and/or fatigue cracking in a period less than the anticipated design life of the roadway. Recent research and development efforts in the Strategic Highway Research Program (SHRP) focused on the establishment of performance-based asphalt binder and asphalt mix specifications [1]. The main objectives of SHRP Asphalt Research Program were to investigate why some pavements perform well, while others do not, develop tests and specifications for materials that will outperform and outlast the pavements constructed today, and to work with highway agencies and industry to have the new 1 Associate Professor, Department of Civil Engineering, Hashemite University, Zarqa 13115, Jordan. 2 Assistant Professor, Department of Civil Engineering, Hashemite University, Zarqa, 13115, Jordan. + Corresponding Author: E-mail asi@hu.edu.jo Note: Submitted May 24, 2010; Revised August 22, 2010; Accepted October 7, 2010. specifications put to use [2-3]. The product that was designed by the new mixture design system was known as Superpave. Adjacent countries to Jordan started evaluating the adaptation of the newly developed programs as early as 1992. Saud Arabia listed Superpave in its specification in 2008. In Saudi Arabia, it was found that plain asphalt cement, which is used in road construction, is only suitable for about 40% of the constructed roads [4]. The SHRP program had proven to be beneficial in most, if not all, cases. The development in the program itself is still ongoing. No serious steps were taken toward the adoption of the SHRP program in Jordan. This study was undertaken to evaluate the use of local materials, both asphalt and aggregate, in both Marshall and Superpave mix design procedures and compare between both procedures for the local environmental and loading conditions. Available Mix Design Procedures The major properties to be incorporated in bituminous paving mixtures are stability, durability, flexibility, and skid resistance (in the case of wearing surface). Traditional mix design methods are established to determine the optimum asphalt content that would perform satisfactorily, particularly with respect to stability and durability. There are many mix design methods that are used throughout the world, e.g., Marshall mix design method, Hubbard-field mix design method, Hveem mix design method, Asphalt Institute Triaxial method of mix design, etc. Out of these only two are widely used, namely the Marshall mix design method and Hveem mix design method [5]. Improved Mix Design and Performance Testing In the Hveem mix design method, the Hveem Stabilometer test is an