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Title: Reduction of Flexural Crack Widths Using Synthetic Fibres in Reinforced Concrete

Author(s): Bernard, E. S.

Publication: Symposium Paper

Volume: 343

Issue:

Appears on pages(s): 331-340

Keywords: Crack width, fibre reinforced concrete, post-crack performance, flexure, tension stiffening, conventional reinforcement

Date: 10/1/2020

Abstract:
The use of steel fibres to reduce the width of flexural and tensile cracks in reinforced concrete members is now well recognised and aspects of this phenomenon have been incorporated into several codes internationally. Almost all the research work upon which this has been based has involved hooked-end steel fibres, with very little work undertaken using other types of fibre. However, the theories underlying how fibres assist in reducing crack widths are not specific to hooked-end steel fibres, so alternative types of fibre could work in a similar way to reduce crack widths in flexural and tensile members. The current paper outlines work recently completed on the effect of several types of synthetic fibre on flexural crack widths in reinforced concrete members. The fibres have predominantly been manufactured using polypropylene, but other materials including aramide, nylon and PVA can also be used for this purpose and have been included in this investigation. Laboratory testing has demonstrated that synthetic fibres are fully capable of reducing flexural crack widths, but their efficacy is not consistent across all fibre types and designs. Testing appears to demonstrate that for a given dosage rate of fibre, the capacity of a FRC mix to limit flexural crack widths is related to the post-crack residual strength. However, some fibres can limit crack widths more effectively than is predicted by existing expressions for design width that are based primarily on post-crack residual strength. This suggests that post-crack toughness is not the only parameter contributing to crack width reduction in Reinforced Concrete members.




  

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