Spatial Imaging of Cracks in Fiber Reinforced Cementitious Composites by EIT

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Title: Spatial Imaging of Cracks in Fiber Reinforced Cementitious Composites by EIT

Author(s): T.-C. Hou and J.P. Lynch

Publication: Special Publication

Volume: 252

Issue:

Appears on pages(s): 53-72

Keywords: damage detection; electrical impedance tomography; engineered cementitious composites; structural health monitoring

Date: 3/1/2008

Abstract:
Cementitious materials are generally classified as semi-conductors that are capable of carrying electricity when an external electrical signal is applied. The electrical properties of cementitious materials have been widely explored for monitoring their internal hydration processes. However, comparatively less work has been done in using the inherent electrical properties of cementitious materials for structural health monitoring. In this study, the electrical properties of a unique strain-hardening fiber reinforced cementitious composite termed Engineered Cementitious Composite (ECC) are utilized for monitoring the performance and health of ECC structural components. Previous work has utilized two- and four-point probe techniques for measuring ECC bulk conductivity and illustrating the piezoresistive properties of the material. This work introduces electrical impedance tomography (EIT) as a powerful sensing methodology that measures the spatial distribution of conductivity over large areas of ECC elements. With a tomographic mapping of ECC conductivity, the distribution of strain fields and cracks in ECC elements can be observed in incredible visual detail.