The rate dependency of concrete under tensile impact loading. Fracture energy and fracture characteristics

To predict the behaviour of concrete structures under impact and explosive loading numerical models are often used. The increase in tensile strength with increasing loading rates is already included in most dynamic concrete models. Often it is assumed that for the fracture energy and the characteristics of the fracture zone the same rate dependency relation counts as determined for the strength increase. This can lead to unreliable risk assessment and counter measures. Therefore, an experimental program has been defined to determine these properties of concrete and to study the mechanisms behind the rate effect of concrete. The experiments, the results and the mechanisms are presented in this paper