6. Conclusion

In this chapter, we analyzed effects of different types of damage on the nonlinear properties of concrete using longitudinal direct transmission mode measurements. Our results suggest that, despite the damage origin (mechanical stress, thermal actions, corrosion, etc.), nonlinear ultrasonic measurements could be a useful tool for monitoring damage. In particular, the analysis performed in the time domain using the scaling subtraction method allows obtaining a sufficiently large signal-to-noise ratio, which is not always the case with standard analysis in the frequency domain. Furthermore, the high sensitivity to the appearance of degradation allows to provide precursory indications with approaching rupture. Further
