Controlled Dynamic Cracking of High‐Strength Concrete Specimens

Abstract

A new method of studying the dynamic development of microcracks in hardened cement paste (HCP) plates subjected to dynamic load sources was developed by Avnon and Yankelevsky in 1991. This method is used to study the dynamic response of high‐strength‐concrete (HSC) two‐dimensional samples. The dynamic loading is produced by special cylindrical explosive charges containing about 10 mg PETN each. When initiated, these charges produce a dynamic pressure pulse for about 3 ms. The charges are inserted inside boreholes perpendicular to the plate faces in predefined locations. The dynamic loading causes cracking to the plates, enabling the measurement of the crack‐propagation velocity and to investigate the crack‐interaction phenomenon. Crack‐propagation velocities were found to be in the range of 60–400 m/s, much lower than the theoretical values. The new method enables simple measurements of crack‐propagation velocities in HSC samples of different shapes and dimensions under dynamic tensile stresses, including small samples, in which crushing of concrete is observed in common methods during similar tests.