Moisture Measurements in Masonry Materials by Time Domain Reflectometry

Time domain reflectometry (TDR) has been evaluated as a tool for the measurement of the moisture content of masonry materials. To this aim, the relationship between relative dielectric permittivity, measured by TDR, and volumetric water content, measured gravimetrically, has been experimentally determined over samples of three cement mortars and a clay brick. The obtained experimental points do not fit the calibration curves available in literature for other porous materials, such as soils and rocks. Instead, specific calibration relationships have been determined. The obtained results show that in all cases dielectric permittivity is highly sensitive to moisture variations, indicating TDR as a promising tool for moisture measurement of building materials. Owing to the feasibility of the proposed experimental procedure for moisture measurements of real masonry walls, the technique appears to be suitable for field monitoring applications.