Abstract: In this paper, recycled coarse aggregate was used to replace natural coarse aggregate, and fly ash was used to replace 20%, 30%, 40%, 50% and 70% (mass fraction) of cement, respectively. The full recycled self-compacting concrete with different water-binder ratios (0.36, 0.40 and 0.45) was prepared. Through flexural strength and compressive strength tests, the effects of fly ash content and water-binder ratio on the performance of full recycled self-compacting concrete were analyzed. The reasonable content of fly ash was obtained, and the calculation formula suitable for flexural strength of full recycled self-compacting concrete was proposed. The results show that when fly ash content increases from 20% to 40%, the slump expansion of all recycled self-compacting concrete mixtures increases first and then decreases, and all of them show good clearance capacity, but the expansion time T₅₀₀ of concrete mixture is not significantly affected by fly ash. With the increase of fly ash content, the compressive strength and flexural strength of fully recycled self-compacting concrete increase first and then decrease, and the flexural strength is more affected by fly ash content than compressive strength. The compressive strength and flexural strength of fully recycled self-compacting concrete are affected by water-binder ratio to the same extent. Based on the effect of fly ash content on the workability and mechanical properties of fully recycled self-compacting concrete, it is suggested that the replacement rate of fly ash to cement is 30%.

Key words: self-compacting concrete, recycled concrete, fly ash content, workability, compressive strength, flexural strength