Tensile damage in concrete: Analysis of experimental technique

Characterization of the tensile behavior of unreinforced and fiber-reinforced cement and concrete is delicate because of strain localization, which introduces a strong heterogeneity of the strain throughout: the specimen and complicates the interpretation of test data. An experimental technique to distribute damage is analyzed in the framework of continuum damage mechanics by introducing internal variables to model the degradation mechanisms taking place in this configuration. A mechanism-based formulation is used to derive the state potential and the kinetic laws. Comparisons are performed for cement matrices with different volume fractions and orientations of short fibers. The paper shows the shortcomings of this experimental technique, though it is still possible to use it to compare the responses of plain and fiber-reinforced concrete.