Abstract: Today, the use of recycled aggregates as a substitute for a part of natural aggregates in 14 concrete production is increasing. This approach is essential because the resources of natural 15 aggregates are decreasing in the world. In the present study, the effects of recycled concrete 16 aggregates as a partial replacement for fine (by 50%) and coarse aggregates (by 100%) were 17 examined in the self-compacting concrete mixtures which contain air-entraining agent and silica 18 fume. Two series of self-compacting concrete mixes have been prepared. In the first series, fine and 19 coarse recycled, respectively with 50% and 100% replacement; with air entraining agent was used 20 in the mixtures. In the second series, fine recycled (with 50% replacement) and coarse recycled 21 (with 100% replacement) were used with silica fume. The rheological properties of the SCC were 22 determined using slump-flow and J-ring tests. The tests of compressive strength, tensile strength, 23 and compressive stress-strain behavior were performed on both series. The results indicated that 24 air-entraining agent and silica fume have an important role in stabilization of fresh properties of 25 the mixtures. The results of tests indicated a decrease in compressive strength, modulus of 26 elasticity and energy absorption of concrete mixtures of concretes containing air entrained agent. 27 Also, the results showed that complete replacement (100%) of coarse recycled had no significant 28 effect on mechanical strength, while replacement of 50% fine recycled has reduced compressive 29 strength, tensile strength and also energy absorption.
