Portland cement concrete is one of the most widely used construction materials. Every year significant portion of concrete used in railway industry is consumed for making concrete sleepers, and application of concrete sleepers is so widespread and extensive that even for rebuilding or improving old railway lines, wooden or steel sleepers are substituted by concrete ones. According to extensive use of concrete and increasing demand for cement in order to provide that, considering harmful environmental effects of producing cement, including the 7% of CO 2 emission in atmosphere and significant consumption of energies such as electricity and fossil fuels, is an inevitable issue and providing alternative productions in order to move through sustainable development and reducing these effects is essential. One of the strategies to produce a concrete compatible with environment is using alkali activated concretes, which is made by activating alumina silicate materials with alkaline solutions and curing at room temperature range till a maximum of 120 °C. Alkali activated slag concrete is a combination of blast furnace slag and alkaline solution that is used as a binder. Good rate of strength development and final strengths, reduction of energy and natural resources consumption and low environmental effects due to low volume of emitted CO 2 , has caused theses kind of concretes to be increasingly considered as a proper alternative for ordinary portland concretes, especially in precast applications. In this research work, the application of alkali activated slag concrete in railway sleepers has been studied. By using blast furnace slag from Isfahan steel plant and activating it by alkaline solution containing sodium hydroxide and sodium silicate, and by considering the effective and salient factors in producing this concrete including: concentration of sodium hydroxide solution, sodium hydroxide to sodium silicate ratio, alkaline solution to slag ratio, and aggregate content by Taguchi method, optimal mixture design has been obtained according to regulations of concrete sleepers production. By using the optimal mixture design, 2 prestressed concrete sleeper sample was built in Karaj factory and static bending test was carried out on it. The effect of factors such as different curing conditions, addition of superplasticizers, change in water to solid ratio, and addition of zeolite on workability, 7-days and 28-days compressive strength and flexural strength has been investigated. All tests were undertaken according to ASTM and BS requirements. The results showed that heat curing accelerates the rate of ultimate strength development; however water curing results in the most 28-day compressive strength in comparison with other methods (heat curing and room-temperature curing). The results also showed that addition of Naphthalene-based superplasticizer does not has a significant effect on workability and strength in this case; but change in the water to solid ratio would significantly affect workability and strength of the concrete. Moreover, suitable percentage of addition and replacement of zeolite to achieve maximum compressive strength is determined 15% by slag weight. Based on the results of this thesis and by considering technical issues related to concrete sleepers productions, it can be concluded that alkali activated slag concrete would meet valid regulations and standards about production of railway sleepers and it is expected that this kind of concrete would be a proper alternative for ordinary concretes in manufacture of railway sleepers. Key Words: alkali activated slag concrete, compressive strength, flexural strength, workability, railway sleepers.