CEE Seminar: Ultrasonic Characterization of Microcracking Damage and Healing in Concrete
Department of Civil Engineering
University of Nebraska-Lincoln (UNL)
Abstract: Most concrete deterioration types manifest in the form of microcracking damage. However, conventional ultrasonic nondestructive testing (NDT) methods for concrete are insensitive to small defects, because low frequency ultrasonic waves are typically used to avoid strong scattering by aggregates. New NDT technologies are needed to characterize microcracking initiation/development at early stage, and/or monitor the healing process in concrete. Diffuse wave and nonlinear ultrasonic wave analyses are promising new NDT technologies for micro-damage evaluation. In this presentation, Zhu will first review the theoretical background and recent development of diffuse wave and nonlinear ultrasonic methods, and then present two recent findings in Zhu’s research group. First, diffuse wave analysis is applied to monitoring the microcrack healing process in mortar by biomineralization; second, diffuse wave and nonlinear ultrasonic wave methods are used to monitor and characterize micro-damage in concrete induced by different kinds of deterioration mechanisms, including ASR and thermal damage. Based on these findings, an innovative nonlinear NDT method is proposed for in-situ evaluation of large scale concrete structures.
Bio: Jinying Zhu is an associate professor in the Department of Civil Engineering at the University of Nebraska-Lincoln. She received her doctorate in civil engineering from the University of Illinois at Urbana-Champaign. Her research interests include NDT for concrete, wave propagation, cement material characterization using ultrasonic waves and innovative sensing techniques. Her research has been sponsored by multiple U.S. federal and state agencies (NIST, DOE, DOT, NSF, DOD). Zhu is a recipient of the ASNT Fellowship Award in 2012, and a four-times winner (with graduate students) of the ACI-James Instruments Award. She serves as an associate editor of the Journal of Nondestructive Evaluation.