1Paper for presentation at the 13thConference on Pavement Engineering, Hsin Chu, Taiwan, 13-14 October 2005. Fundamentals and Practice of Asphalt Mixture Design Procedures to Assure Adequate Performance By: Mang Tia Professor of Civil & Coastal Engineering, University of Florida. P. O. Box 116580, Gainesville, FL 32611-6580, U.S.A. E-mail: [email protected]Abstract: This paper presents the fundamental principles and practice of four commonly used asphalt mixture design procedures in the United States. The methods covered include the Marshall, Hveem, Superpave and GTM mix design methods. Emphasis is placed on comparing them with regards to the three main elements of mix design procedures, namely (1) the method for preparation and compaction of the asphalt mixtures, (2) the properties of the compacted specimens to be measured, and (3) the criteria used for selecting acceptable and optimum mix designs. The possible merits or fallacies of each method are discussed. Introduction The design of an asphalt paving mixture usually involves selecting the aggregates, asphalt and additives to be used, testing the asphalt mixtures at various different proportions of the ingredients, and selecting the optimum mix design which would give the best anticipated performance in service. Ideally, the mixtures to be tested should be prepared and compacted to as close to the field condition as possible, so that they can be representative of the mixtures to be produced and put in service. The properties of the mixtures to be determined should be good indicators of performance of the mixtures in service, so that these properties can be used to determine the acceptability of the mixtures and to select the optimum mix design to be used. A design procedure for asphalt mixtures generally involves (1) preparing and compacting the asphalt mixtures in the laboratory to simulate the field condition, (2) characterizing the laboratory compacted specimens, and (3) determining the optimum mix design based on the properties of the tested specimens and the set criteria for these properties. Different design methods generally differ from one another by (1) the equipment and method used to prepare and compact the asphalt mixtures, (2) the properties of the compacted specimens to be measured, and (3) the criteria used for selecting acceptable and optimum mix designs. This paper presents the general methodologies of four different mix design methods for dense-grade HMA mixtures, which include the Marshall, Hveem, Superpave and GTM methods. Emphasis is placed on the three main elements as described above, so that these different design
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