Practice report

Prototype application of photo-optical moisture sensors

Fig. 1 Photo-optical single- and multi-segment moisture sensor [1, 2]

Fig. 2 Application of several photo-optical moisture sensors in brickwork [1, 2]

Fig. 3 Loss of mass of specimens over time

Fig. 4 Temperature curve inside the testing facility

Fig. 5 Humidity curve inside the testing facility

Fig. 6 a: Photo-optical moisture sensors; b: Test setup with measured specimens

Fig. 7 Photodiode voltage over time in cement screed

Fig. 8 Photodiode voltage over time in CaSO₄ float finish

Fig. 9 Specimen (a) with fitted photo-optical moisture sensor (b)

Fig. 11 Calibration curve of the photodiode voltage as a function of the degree of moisture penetration (Dfg) in percent by volume of the CaSO₄ float finish

Fig. 10 Brick wall with applied photo-optical moisture sensor

This article presents a photo-optical method for measuring the moisture content of porous building materials. A series of moisture diagnostics tests was performed for porous building materials using photo-optical sensors. Such testing is currently unique in the construction sector in the German state of Thuringia. Measurements were carried out during the setting and hardening of various screeds.

The construction sector increasingly relies on the monitoring of the condition of buildings and structures. Both for new projects and existing buildings, the collection of building information is crucial for the purposes of quality assurance, repair and maintenance, and the assessment of the condition of buildings. In the construction industry, emphasis needs to be put not only on latest technological advancements but also on changes in quality assurance, safety and related monitoring measurements.

A new laboratory-scale measuring method was developed at the chair for construction chemistry at...