Steel fibre composite bars

Rebars are polymer fibre reinforced-concrete composites, and they are used as primary structures. It is estimated that replacement of steel reinforcing bars by non-corrosive polymer fibres, i.e., by Kevlar or carbon fibres (which gives rise to Kevlar or C-composite bars) for concrete structures produces structures with one-quarter the weight and twice the tensile strength of the steel bar. It is known that, corrosion of steel reinforcement from carbonation or chloride attack can lead to loss of the structural integrity of concrete structures, and such a danger is non-existent for rebars. Thermal expansion coefficient (TEC) values of these fibres are closer to concrete than that of steel, which provides an another advantage and they have the same surface deformation patterns as the steel bars. In addition, they can provide more economy than epoxy-coated steel bars. 

A.K. Panda, R.A. Spencer and S. Mindess, Bond of deformed bars in steel fibre reinforced concrete under cyclic loading , IntJ. Cement Composites and Lightweight Concrete. 8,1986, 239-249. 

A. Bentur and S, Mindess, Concrete beams reinforced with conventional steel bars and steel fibres Properties in static loading , Int. J. Cement Composites and Lightweight Concrete. 5,1983,199-202. 

If concrete removal is not required or supplementary reinforcing bars cannot be used, external reinforcement can be applied. For instance, steel bars may be encased in a shotcrete layer or steel plates may be bonded onto the concrete surface. Recently, the use of steel plates has been substituted by fibre-reinforced plastics (F. R.P.), that are composite materials with glass, aramide or carbon fibres embedded in a polymeric matrix (usually an epoxy system). F. R.P. are available in the form of laminates or sheets that are bonded to the concrete surface using an epoxy adhesive [11]. They are typically used to improve the flexural and shear strength or to provide confinement to concrete subjected to compression. The... 

The distinction between composite materials and composite structures is not sharp and laminated composites form a group that may be logically considered for different purposes either as materials or as structures. Composite materials are used to build up composite structures, but homogeneous ones may also be used. It is usual to consider concrete and fibre-reinforced concrete as composite materials. A concrete beam reinforced with steel bars or a set of steel beams connected together with a concrete steel-reinforced slab to create... 

The short dispersed or long fibres, and also polymers, which impregnate the void systems, are used as reinforcement. Hard grains of any dimension also play a role in reinforcement of the matrix. If the reinforcement has a form of regularly distributed steel bars, tendons or cables, according to the classification proposed in Section 2.3.1 it is a composite structure rather than a material. 

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