A new sensorized ceramic plug for the remote monitoring of moisture in historic masonry walls: First results from laboratory and onsite testing

The presence of moisture in historic buildings, especially from rising damp, is extremely widespread and severe, causing materials' deterioration, internal discomfort and bad thermal insulation of external walls. Although this phenomenon is widely studied in the literature, the available solutions are frequently only partially effective, also due to the lack of reliable and compatible techniques to monitor the amount of moisture inside porous building materials, especially in heritage buildings where multiple restrictions exist. In this paper, a new sensorized ceramic plug was developed, to be inserted in historic masonry walls for the remote monitoring of moisture. The plug includes a moisture sensor that is currently used for soil irrigation purpose in agriculture and a ceramic envelope of tailored properties. The plug was developed in laboratory following a step-by-step testing program, which took into account both the specific features of the sensor (requiring a strong research effort to be transferred to building materials) and those of historic walls. After a first set of laboratory tests, the sensorized ceramic plug was validated in small-scale laboratory walls and in a real historic masonry in the monumental Certosa cemetery in Bologna, Italy. The results are extremely encouraging, as they show how the new plug can provide valuable information about the rising damp evolution, and in fact, the data were correlated with the changes in the concurrent environmental parameters in the area of the cemetery. The results also suggest some possible measures to improve the sensorized ceramic plug in the near future.