Abstract: Compared to normal aggregates, recycled aggregates have lower mechanical properties, higher water absorption and porosity, which result in poorer mechanical properties of recycled aggregate concrete made from recycled aggregates. This article conducted experimental researches on the splitting tensile mechanical properties of steel fiber recycled aggregate concrete by combining steel fiber and consolidate recycled aggregate, combined with digital image correlation technology and electro-hydraulic servo testing machine. Simultaneously, applying microscopic testing techniques, the influence mechanisms of steel fiber content and consolidate recycled aggregate on the tensile properties of steel fiber recycled aggregate concrete were revealed from the perspectives of interface morphology and interface scale. The results indicate that when the content of steel fiber is high, the influence of aggregate type on the failure mode of concrete is no longer significant. The splitting tensile failure mode of concrete containing steel fiber shows multiple cracks and toughness characteristics. The tensile strength of consolidate recycled aggregate concrete increases by 2.56% to 3.50% compared to normal concrete. The tensile strength of consolidate recycled aggregate concrete is most significantly affected by the steel fiber content, with a maximum increase of 40.50%. The crack resistance of both consolidate recycled aggregate concrete and recycled aggregate concrete are more significantly affected by the content of steel fiber than that of normal concrete. The research results can provide important theoretical basis for the strengthening research and engineering application of recycled aggregate concrete.

Key words: steel fiber, recycled aggregate concrete, consolidate recycled aggregate, tensile strength, microscopic characteristic