As natural aggregate sources are becoming depleted due to high demand in road construction and the amount of disposed waste material keeps increasing, researchers are exploring the use of alternative materials which could preserve natural sources and save the environment. In this study, steel slag was used as an aggregate replacement in conventional dense graded asphalt mixes (ACW14 and ACB28). Steel slag was selected due to its characteristics, which are almost similar to conventional aggregates, and the fact that it is easily obtainable as a by-product of the steel industry. The same gradations of mixtures were produced using normal crushed aggregate as control samples. The Marshall mix design system was used for sample preparation in accordance with Malaysian specifications. Samples of asphaltic concrete were subjected to the resilient modulus test, creep test and rutting test. Samples made from steel slag show significantly better results than conventional aggregate. Therefore, utilization of steel slag will reduce land fill, save natural resources and improve the strength of pavement to sustain a higher volume of vehicles. This will shift the gear in sustainable pavement construction, which is most desirable in today’s energy deficient world. 1. Introduction The development of the highway construction industry is increasing rapidly. Consequently, the aggregate resources in Malaysia are becoming depleted, and the land is being sacrificed to obtain raw materials. Thus, it is necessary to find a recycled material that can replace aggregates in highway construction. Much research has been done to improve and upgrade the materials used for preparing hot-mix asphalt (HMA). The utilization of waste material as a replacement for aggregates in the production of HMA could have many benefits to mankind. Waste materials can be categorized broadly as follows: industrial waste (e.g., cellulose waste, wood lignins, slags, bottom ash, and fly ash), municipal or domestic waste (e.g., incinerator residue, scrap rubber, waste glass, and roofing shingles) and mining waste (e.g., coal mine refuse) [1]. Steel-slag is a byproduct of the steel industry, and is reported to exhibit great potential as a replacement for natural aggregates in road construction. Steel-slag is a waste material that can be recycled as a road construction material. Steel-slag aggregates have been reported to retain heat considerably longer than natural aggregates. The heat retention characteristics of steel-slag aggregates can be advantageous for HMA construction, as less gas (energy) is used
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