MOISTURE CONTENT ESTIMATION IN YELLOW NEAPOLITAN TUFF AND CLAY BRICK BY TDR

Time Domain Reflectometry (TDR) is a proven technology for the evaluation of soil moisture, which is increasingly finding application in the field of moisture measurement in porous building materials. In this work TDR technique is used to estimate water content of two building materials commonly used for masonry: yellow Neapolitan tuff and clay bricks. The two specimens were first instrumented with a classic three-rod TDR probe and then saturated by immersion. The moisture measurements were carried out during the drying phase, coupling TDR readings with gravimetric determinations of water content. Then, empirical relationships linking water content (gravimetrically measured) to the dielectric permittivity of the material (obtained by TDR) were retrieved. In fact, TDR response strongly depends on the water content of a material since the dielectric permittivity of water is about 40 times greater than the one of the dry material. The found calibration curves have a clear trend and confirm the suitability of TDR for the estimation of water content in porous building materials