Advances in experimental assessment of dynamic tensile strength of concrete by the spalling technique

An experimental method to test concrete in dynamic tension by spalling with a Hopkinson bar as loading and measuring tool was developed in 1999. The dynamic strength of concrete specimen and strain rate were indirectly derived from an accurate data processing of the signals measured on the Hopkinson bar surface. This method suggested by late Prof. Klepaczko, allowed for reaching the highest strain rate reported in literature for which an intriguing tensile strength increase was highlighted. This simple and efficient technique has been adopted by many researchers around the world. Some significant improvements in terms of definition and reproducibility of the incident loading pulse travelling along the bar and direct and/or contactless measurements on concrete specimens have been introduced. The very high rate sensitivity of concrete tensile strength was corroborated by the additional experimental data obtained with this experimental technique during the last fifteen years.