As the nation’s infrastructure system ages, condition assessment of traditional civil engineering materials has become a critical issue for sustainability and economical infrastructure management.  However, existing nondestructive evaluation (NDE) methods for infrastructure applications do not have the degree of accuracy, reliability, and repeatability necessary for the quantitative assessment of civil materials. This seminar reports on recent applications of ultrasonic wave based techniques for the quantitative NDE of civil infrastructure.  Specific examples discussed will include: a combination of laser ultrasonic, signal processing and analytical modeling techniques to examine the propagation of transient Lamb waves in viscoelastic plates (with applications for repaired concrete); the quantitative characterization of the microstructure of cement-based materials using diffuse and coherent ultrasonic waves; and the development of a focused, air-coupled ultrasonic source in a frequency range relevant for civil infrastructure.  The underlying hypothesis of this research is that ultrasonic techniques can be used to make in situ measurements of critical parameters that characterize the current state of, and then to track the degradation of civil infrastructure.