Corrosion of steel rebar in a concrete structure compromises its structural integrity and hence its performance. Chloride intrusion into concrete can lead to depassivation of the steel and initiation of corrosion. Methods exist to detect chlorides in concrete, but the practical use of many of these may be problematic because they are destructive and time consuming, and cannot be used to analyze large structures. Microwave nondestructive evaluation techniques applied to mortar have proven successful for detecting mixture constituents, chloride ingress, and cure-state monitoring. In this paper several concrete samples are cyclically soaked in distilled water and saltwater while also experiencing compression force. Compression force, simulating in-service loading, results in increased microcracking and permeability, which promotes chloride ingress. The daily microwave reflection properties of these samples were measured at 3 GHz. The results show the capability of these microwave measurements for detecting the increased level of chloride permeation as a function of increasing number of soaking cycles. In addition, comparisons between the reflection properties of mortar and concrete cubes soaked in distilled water exhibit similarity in trends, indicating that the various phenomena that occur within them are systematically similar.
J. T. Case et al., "Microwave Reflection Properties of Concrete Periodically Exposed to Chloride Solution of 3% Salinity and Compression Force," IEEE Transactions on Instrumentation and Measurement, vol. 53, no. 4, pp. 1000-1004, Institute of Electrical and Electronics Engineers (IEEE), Aug 2004.
The definitive version is available at http://dx.doi.org/10.1109/TIM.2004.830743
Electrical and Computer Engineering
National Science Foundation (U.S.)
Keywords and Phrases
Concrete Construction; Concretes; Mechanical Permeability; Microcracking; Monitoring; Mortar; Nondestructive Examination; Saline Water; Solutions; Steel Corrosion; Chloride Solution; Compression Force; Cure State Monitoring; Microwave Nondestructive Testing; Microwave Reflection Properties; Reinforcing Steel; Microwave Measurement
International Standard Serial Number (ISSN)
Article - Journal
© 2004 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.