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

• Excellent agreement between experimental pulse velocity of concrete and theoretical results based on scattering models.
• Characterization of damage content based on wave propagation parameters.
• Correlation of acoustic emission parameters with strength.

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.