Dynamic properties of fibre reinforced and plain ultra high performance concretes

Ultra High Performance Fibre Reinforced Concrete (UHPFRC) is a relatively new and expensive type of concrete for general application. However, in situations of dynamic loading such as blast and impact the material may offer great advantages. The principal criteria are the ability of a specimen to withstand singular or repeated blows and to absorb energy. Generally Ultra High Performance Concrete exhibits excellent performance in overall compressive strength compared with traditional concrete, and when enhanced by fibres has significant ductility and tensile/flexural strength. Concrete material properties are strain rate sensitive and it is necessary to take account of this behaviour when considering dynamic loading. This paper reports on research that evaluates the impact-resistance ofunreinforced and fibre enhanced Ultra High Performance Concrete. In particular results are presented that demonstrate how the compressive and flexural behaviour change with loading rate. Static results and results over a range of loading rates have been obtained using conventional hydraulic loading apparatus and a purpose built drop-hammer rig. Specimens include smalJ beams and cylinders (of steel fibre reinforced and plain concrete)