Mehran Shirani Bid Abadi - Department of Civil Engineering, Faculty of Engineering, University of Kashan, Kashan, Iran
Mahmood Akbari - Department of Civil Engineering, Faculty of Engineering, University of Kashan, Kashan, Iran
Omid Panahi Shahri - Department of Civil Engineering, Faculty of Engineering, University of Kashan, Kashan, Iran

The purpose of this study is to analyze the effect of size and level of recycled aggregates on the mechanical properties of concrete and improve them by the fibers. For this purpose, in the first phase, the results show that the replacement of fine recycled aggregate at the level of 30% has no significant reduction effect on the compressive strength of concrete and so this can be selected as the optimum recycled mix design. In the second phase, the results show that the addition of polypropylene and steel fibers considerably improve the tensile and flexural strength of the recycled concrete.

recycled concrete, recycled aggregate, mechanical properties, steel fiber, polypropylene fiber.