Dam Engineering Vol XX Issue 3 235 Asphalt concrete core of the Meijaran dam in brief Alireza Sharifi Soltani, Principal Geotechnical Engineer & Project Manager, BSc & Siavash Litkouhi, Chairman, PhD Soils Engineering Services Co #135, Zhoubin Cul-de-Sac North Dastour Street Gheitarieh Tehran 19317-64611 Iran Email: sharifi@sesce.com / slitkouhi@sesce.com Abstract The lack of clay borrow sources at the Meijaran dam site, along with a high annual precipitation rate in the area, led consulting engineers to replace the clay core with an asphalt concrete core (ACC) at the rockfill dam. The steps taken for the project from the start, i.e. the selection of suitable aggregate sources for the asphalt concrete (AC) and the adjacent filter materials to the end, i.e. ACC placement in the dam body, are briefly discussed. AC mix design parameters, which were finalized upon completion of laboratory tests are presented, as well as the scope of trial placements conducted for optimizing the hand - and machine - placement of the ACC. Proper results were gained both in the final trial placement and in the dam body, in accordance with the quality control program. The air void contents measured in the AC cores were all below three percent. Construction of the dam took about 18 months which, when compared with the placement of a clay core, is a very short length of time for dam construction activities along the northern coastal region of Iran. The Yangtze Three Gorges Technology & Economy Development Co (TGDC) supervised the whole work. Keywords: Asphalt concrete core, clay core, rockfill dam, Marshall test, air void con- tent, trial placement, hand placement, machine placement, drilled core. 1. Introduction For many years clay core has been conventionally used in embankment dams, as a sealing element in the dam body. However, when there is a lack of clay borrow sources at the dam site, or it is not available within an economically viable distance