Abstract:Orthogonal experiment method was applied to analyze the strength properties of steel fiber reinforced fly ash recycled concrete. The effect of the fly ash replacement rate, steel fiber content and recycled coarse aggregate replacement rate was investigated on the 28d cube compressive strength, splitting tensile strength and flexural strength. Test results show that the influence of fly ash replacement rate on the compressive strength is the same as on the flexural strength, but for the splitting tensile strength is not the case. Compressive strength, splitting tensile strength and flexural strength increase with the increase of steel fiber content, however, steel fiber content has significant effect on the splitting tensile strength and flexural strength, and little effect on the compressive strength. The influence of recycled coarse aggregate replacement rate on the compressive strength, the splitting tensile strength and flexural strength is the same. The strength increases with the increase of recycled coarse aggregate replacement rate. To improve recycled concrete strength, it is necessary to reduce the fly ash replacement rate, and to increase the steel fiber content and recycled coarse aggregate replacement rate. If fly ash replacement rate is below 30% and steel fiber content is below 18%, the fly ash replacement rate plays the most significant role on the compressive strength, followed by the recycled coarse aggregate replacement rate and steel fiber content. The steel fiber content plays the most significant role on the splitting tensile strength and flexural strength, followed by the fly ash replacement rate and recycled coarse aggregate replacement rate.