The ability of fibre reinforced concrete composites to absorb energy has long been recognised as one of the most important benefits of the incorporation of fibres into plain concrete” (Golpalaratham and Gettu 1995). Steel and synthetic fibres have been used in concrete floor slabs with success in providing crack control. Slab design using synthetic fibres relies heavily upon manufacturers design guidance whereas steel fibres have better developed independent design guides available to assist their correct use (The Concrete Society 2007a). This paper examines the pull out values of both steel and Type 2 synthetic fibres embedded in concrete and equates their dosage when used in beams to provide near equal toughness values, thus providing the designer with a synthetic/steel fibre ratio by mass of fibre addition for equal performance. According to Nataraja, et al (2000), the most common method to measure toughness, is to use the load-deflection curve. One of the most widely used load-deflection tests has been ASTM 1018, which was used herein to evaluate the post crack toughness; by stating toughness as independent indices and residual strengths based upon the deflection at the formation of the first crack in the beam in relation to fixed points of further deflections under load. The ASTM test was chosen as it has been widely used and it is readily understood by many readers. The research demonstrates that near equal post crack toughness can be achieved in concrete beams using steel and synthetic fibres, at different doses.
|Northumbria Working Paper Series: Interdisciplinary Studies in the Built and Virtual Environment
|Published - Dec 2009