Abstract

Evaluation of water distribution and its temporal movement in cement-based materials is important for assessing cement hydration, curing, and long-term performance. From a practical standpoint, it is also important to obtain this information nondestructively. Near-field microwave nondestructive evaluation methods have proven effective for evaluation of cement-based materials for their various mixture properties, including the detection of salt added to the mixing water and chloride ions entering these materials through exposure to salt water solutions. Electromagnetic modeling of the interaction of microwave signals with moist cement-based materials can provide the necessary insight to evaluate water content distribution and movement in these materials. To this end, the temporal microwave reflection properties of a mortar cube, subjected to cycles of wetting and drying, were measured at 3 and 10 GHz using open-ended rectangular waveguides for several cycles, each lasting about 35 days. A semiempirical electromagnetic model, based on modeling the cube as a layered structure with each layer having a different dielectric constant, was then developed to simulate the measured reflection properties. The simulated and measured results were obtained for both frequencies and, for all cycles, were in good agreement. The most important outcome of the model is the temporal behavior of water content distribution and, hence, its movement in the mortar cube. This paper presents a brief description of the measurement approach and a detailed description of the model. A detailed discussion of the results and its sensitivity to various parameters is also provided.

Department(s)

Electrical and Computer Engineering

Keywords and Phrases

10 GHz; 3 GHz; Cement Curing; Cement Hydration; Cement Long-Term Performance; Cement Mixture Property Evaluation; Cement-Based Material Evaluation; Cement-Based Materials; Cements (Building Materials); Chloride Ions; Concrete; Cyclically Soaked Mortar; Dielectric Constant; Electromagnetic Modeling; Microwave Measurement; Microwave Signal Interaction; Microwave Signals; Microwaves; Mixing Water; Mixtures; Moist Substances; Moisture Measurement; Mortar; Mortar Cube; Near-Field Microwave Nondestructive Evaluation; Nondestructive Testing; Open-Ended Rectangular Waveguides; Salt Detection; Salt Water Solutions; Semiempirical Electromagnetic Model; Temporal Microwave Reflection Properties; Temporal Movement; Temporal Water Content Distribution; Temporal Water Content Movement; Water Content Distribution Evaluation; Water Content Distribution Temporal Behavior; Water Content Movement Evaluation; Water Distribution Evaluation; Infrastructure Testing and Cement-Based Material Evaluation; Material Characterization

International Standard Serial Number (ISSN)

0018-9456

Document Type

Article - Journal

Document Version

Final Version

File Type

text

Language(s)

English

Rights

© 2004 Institute of Electrical and Electronics Engineers (IEEE), All rights reserved.

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