Experimental Study On The Mechanics Behavior Of Steel Fiber Recycled Concrete Beams With Different Recycled Aggregate Rate

In recent years, a lot of construction waste is produced with Chinese acceleratingurbanization, which waste concrete occupies a large part of. Because the concrete can’t bedegraded, serious damage is taken to the environment. How to deal with the increasing wasteconcrete becomes the problem must to be solved quickly by Governments. Recycled concrete,which can re-use the waste concrete, largely contributed to the harmonious development ofthe ecological environment, but the mechanical properties and durability of recycled concreteare below than ordinary concrete, which severely restricted the application of the recycledconcrete in the actual project. As we all know, steel fiber reinforced concrete has a good crackresistance, if we can organically combine steel fiber and recycled concrete, to make fulluse of their advantages, it will provide the recycled concrete used in structural engineeringwith a broader prospects.This paper researches bearing capacity variation, cracks developments and stiffnessvariation of the steel fiber recycled concrete beams, by changing the different recycledaggregate replacement ratio, producing three steel fiber reinforced recycled concrete beamsand one steel fiber reinforced concrete beam to test and analyze. on this basis, with referenceto the current design of concrete structures (GB50010-2010) and the fiber reinforced concretestructure technical regulations (CECS38:2004), it discussed more piratical flexural bearingcapacity of steel fiber recycled concrete beams, crack width and stiffness formula.Based on the test results and the data analysis, this paper mainly found the followingconclusions:(1)Steel fiber recycled concrete beams are largely in line with the assumption of planesection.(2)In the case of reinforcement ratio and steel fiber volume ratio unchanged, with theincrease of recycled aggregate quantity, the capacity of normal section of Steel fiber recycledconcrete beams linearly reduces，whose reduced frequency satisfies κ=1-0.17η.(3) The crack development of Steel fiber recycled concrete beams is basically the sameto steel fiber concrete beam, In the case of reinforcement ratio and fiber volume ratiounchanged, with the increase of recycled aggregate quantity, the number of cracks in thebeam represents a tendency of reduction, while the maximum crack width increases linearly,The increased frequency satisfy ψ=0.14~η~2+0.05η+1.(4) In the case of reinforcement ratio and fiber volume ratio unchanged, with the increaseof recycled aggregate quantity, the deflection of the beam rises, while the stiffness decreaseslinearly, whose reduced frequency satisfies β=0.16-η~2-0.08η+1. (5) Based on the experimental data, put forward the coefficient suitable for the ratio ofsteel fiber recycled concrete and steel fiber reinforced concrete axial compressive strengthdesign value λ, where λ=1-0.3η, established the normal section bearing capacitycalculation method of steel fiber recycled concrete beam.(6) Based on the experimental data, put forward coefficient suitable for the ratio of Steelfiber recycled concrete and steel fiber reinforced concrete axial tensile strength standard value α,whereα=1-0.66η~2, established the maximum crack width calculation method of steelfiber recycled concrete beam.(7) Based on the experimental data, put forward coefficient suitable for the ratio of steelfiber concrete and steel fiber recycled concrete elastic modulus δ, where δ=1-0.65η~2,established the stiffness calculation method of steel fiber recycled concrete beam.