New Sensors for Moisture Monitoring in Historic Walls: Preliminary Results

The presence of moisture in historic masonry walls represents one of the main sources of decay for cultural heritage and materials, besides causing unhealthy indoor conditions and worsening the thermal performance of the building envelope. In fact, moisture causes and/or exacerbates different deterioration mechanisms, such as salt crystallization, freeze-thaw cycles, biological growth, etc. Given the importance of moisture in materials, there are many techniques aimed at determining moisture content in structures, but the most common ones only provide qualitative results or do not allow reliable repeated measurements over time, which is a severe limitation when continuous monitoring is necessary. In this perspective, the MIMESIS project (funded by Emilia-Romagna Region, Italy) aims at developing a range of sensorized materials for the remote monitoring of moisture, temperature, pH and detachment, useful to determine the ‘health state’ of historic buildings. It is also expected that the sensorized materials give a warning when critical situations are reached, allowing to carry out adequate interventions before irreversible damage occurs. In this paper, a brick-based sensor suitable for measuring moisture content in masonry was developed and tested. The sensing element was originally designed for agriculture, to measure the ‘soil water tension’, hence an investigation about the applicability to building materials and a calibration in bricks was necessary. The results are encouraging and suggest that this new sensorized brick could be applied for the continuous monitoring of moisture in historic masonry.