Hardened concrete. Test method for fundamental transverse, longitudinal and torsional frequency of concrete specimens.
Defines the test procedures for determining the fundamental resonance frequencies - flexural, torsional and extensional (or longitudinal) - on concrete specimens prepared on site or in the laboratory. The fundamental resonance frequency is the lowest frequency value corresponding to a maximum amplitude of oscillation (standing waves) for the same excitation amplitude. It is applicable for: evaluating changes in the elastic properties of specimens subjected to durability tests, by means of the flexural frequency according to the procedure described in Appendix A; evaluating the dynamic elastic properties - modulus of elasticity (Young's), Poisson's ratio and shear modulus - of specimens by means of the extensional and torsional resonance frequencies according to the procedure described in Appendix B. The elastic properties obtained with this procedure are defined as dynamic and may differ from those obtained with the static method specified in UNI 6556. The comparison between results obtained on specimens of different shapes must take into account any effects introduced into the calculation by the correction factors. Appendix A: Calculation of changes in elastic properties. Appendix B: Calculation of dynamic elastic properties.
