Plenary Session:

Title:           NDE of Cementation Systems using Laser Shearography
Authors:      Amde M. Amde, John W. Newman, Richard A. Livingston
Abstract:    Non-destructive evaluations (NDE) of micro cracks in concrete structures due to damages from delayed ettringite formation and other causes using laser shearography are discussed. Laser Shearography is a full field, non-contact, non-contaminating NDE method and offers near real time inspection of surface and subsurface anomalies in materials or structures by imaging sub-microscopic deformation derivatives of a test part surface when an appropriate stress is applied. Shearography is capable of inspecting structures for defects such as impact damage, delamination, and micro cracks. Our research has shown that laser shearography has an outstanding ability to detect and measure near surface and surface breaking cracks in cementation systems. The laser shearography system can be used in the field under ambient conditions. It has been applied to detect fine cracks in masonry and concrete structures with a resolution better than 10 microns. Moreover, the output of the system is a digital image which can be processed with image analysis software to yield statistics on the crack distribution such as length, width and preferred orientation that can be used to diagnose the cause of the cracks. Since it is a non-destructive method it can be used to make repeated measurements on the same location over time, and thus monitor the propagation of cracks.

Keywords:  Laser Shearography, Concrete, Non-destructive Evaluation, Micro Cracks, Delayed Ettringite Formation
Pages:        002-003

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