Time-domain reflectometry method and its application for measuring moisture content in porous materials: A review

The time-domain reflectometry (TDR) method is based on the analysis of dielectrics’ behavior in time-varying electric field which can be utilized in the determination of permittivity and electrical conductivity of a wide class of materials. Measurement of moisture content in porous materials belongs to its most frequent applications; after several decades of use TDR method became one of the most recognized techniques in this field. In this review, a short historical overview of the TDR method applications is introduced, the function of a typical TDR device is described and the main TDR data interpretation techniques are surveyed first. Then, the methods for determination of moisture content in porous media from the measured relative permittivity are analyzed and prospective ways of their application are identified. Finally, some recommendations for further developments in TDR measurement of moisture content in porous materials are formulated.