Mechanical and fracture behavior of cement-based materials characterized by combined elastic wave approaches

In the present paper cementitious material with simulated damage is examined as to its mechanical and
fracture properties. Nondestructive monitoring techniques are applied in an effort to establish or improve
correlations with the simulated damage content and the failure load. Specifically, the specimens are
ultrasonically interrogated before fracture, while during fracture their behavior is monitored by acoustic
emission. Scattering theory seems adequate to explain the experimental ultrasonic behavior showing
that modern approaches should incorporate the heterogeneity instead of considering the material macroscopically homogeneous. Apart from the strong correlations between wave velocity and damage content
in the form of light inclusions, specific acoustic emission parameters show good correlation not only
to simulated damage content but also to the ultimate bending load. Overall, the suitability of ultrasonic
parameters to investigate damage and of acoustic emission parameters to correlate with failure load are
discussed, while the influence of material's heterogeneity on the distortion of the signals is also
discussed.