This paper investigates the mechanical properties of 10 steel fibre reinforced concrete (SFRC) mixes at fibre dosages of 30, 35 and 45 kg/m 3. Manufactured Steel Fibres (MSF) are used on their own, or blended with sorted steel fibres recycled from end-of-life tyres (RTSF). To characterise the flexural behaviour of the mixes, two flexural test methods, BS EN 14651:2005 3-point notched prism tests and ASTM C1550-05 centrally loaded round panel tests are employed. A strong correlation is found in the flexural behaviour of the SFRC prism and round panel specimens, with corresponding conversion equations proposed. The mechanical properties of hybrid mixes using RTSF vary depending on dosages, but are comparable with those of MSF-only mixes at the same fibre dosage. A positive synergetic effect is derived from hybrid mixes containing 10 kg/m 3 of RTSF.
Fiber blends have the potential to improve the mechanical and sustainability credentials of steel fiber‐reinforced concrete (SFRC), but at which ratios these can work is not known a priori. This paper investigates the uniaxial tensile stress–strain (
σ − ε) relationship of blended SFRC using manufactured steel fibers on their own, or blended with sorted steel fibers recycled from end‐of‐life tires (recycled tire steel fiber [RTSF]), at total fiber dosages of 30, 35, and 45 kg/m3. The accuracy of two
σ − ε relations proposed by RILEM TC 162‐TDF and Model Code 2010 is assessed using the experimental results from concrete prisms. By using nonlinear finite element (FE) analysis, it is found that the RILEM approach can lead to significant overestimation (up to 72%) of peak flexural load and energy absorption capacity (up to 39%), while the Model Code 2010 can provide a rather accurate prediction of the energy absorption capacity and some overestimation (less than 34%) of the peak flexural load. Inverse FE analysis is used to determine indirectly the uniaxial tensile
σ − ε relations of the examined SFRC mixes, and a simplified trilinear relation for SFRC is proposed. It is concluded that the tensile strength of SFRC with RTSF at a low total fiber dosage is only marginally improved by fiber addition, and the postcracking tensile strengths at different strains can be determined directly from residual flexural tensile strengths (f
Ri) of prisms.
The tensile characteristics of rubberised concrete are practically impossible to obtain from direct 4 tensile tests, due to the non-uniform distribution of aggregates and stiffness. In this paper, notched three-point 5 bending tests are used to characterise Mode I fracture behaviour of concrete incorporating high volume of rubber 6 particles obtained from post-consumer tyres. The test results show that rubber particles enhance energy absorption 7 capacity and ductility of concrete. Inverse finite element analysis is performed to indirectly determine tensile stress-8 strain curves of rubberised concrete. The key material parameters introduced in the constitutive model are tensile 9 strength, fracture energy and crack band width. The spurious mesh dependency is resolved by adopting a simple 10 modification to the softening modulus as a function of element size. The performance of the proposed tensile stress-11 strain relation is compared with that of Model Code 2010 using ABAQUS concrete damaged plasticity model and 12 shows considerably better accuracy. The proposed model can be used to improve the reliability of numerical 13 analyses of rubberised concrete elements and structures. 14
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