Measurements of impact tensile strength of concrete and mortar using reflected tensile stress waves

Abstract
A simple measuring method for impact tensile strength of brittle materials is presented and discussed. It is based on the superposition and concentration of tensile stress waves reflected both from the free ends of a striking bar and a specimen bar. The experiment is conducted by means of a Hopkinson bar technique using an air-gun arrangement. The impact tensile experiment of concrete and mortar specimen bars was performed as well as static strength tests of splitting tension, bending, and compression. The experimental data in relation to those strengths were analyzed statistically by means of a Weibull distribution. The impact tensile strengths were significantly influenced by loading rates, and they were found to be from 1.5 to 2 times of the static values. For examining the adequacy and limit of the present measuring method, numerical simulations on the stress waves propagated in the specimen bars were carried out under the condition of two-dimensional axisymmetric model using the FEM code and some reasonable results were found.