Fibre-reinforced concrete, polymeric fibres

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... 

Steel fibres are used for tunnelling, mining and concrete repair, and glass fibres are rather used as reinforcement for cement mortar. Polymeric fibres are used mostly for control of the shrinkage cracking of external layers and as remedy in the case of fire (cf. Section 5.6). 

A similar approach is currently taken for polymeric fibres, which are being developed for semi-structural reinforcement of concrete, to achieve performance equivalent to that of steel fibres. The effect of the crimped shape of polymeric fibres was empirically analysed in terms of the amplitude of each crimp and the density of crimps (i.e. the number of crimp waves along the embedded length). It was shown that the pull-out resistance of each wave was very sensitive to the amplitude of the crimp (Figure 3.34(a)) and the pull-out resistance of each wave ( crimp ) was... 

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