Moisture distribution patterns of layered structural materials in cultural heritage objects

Introduction. The article examines patterns of moisture distribution in the layered structural materials of cultural heritage objects. The distribution of moisture in a porous material is determined by the geometry of the pore space, since a narrower capillary sucks moisture from a wider one. However, studies of the moisture distribution in the layered structure of materials used for the construction of cultural heritage objects shows that this pattern is often absent.

Aim. To identify the prevalence degree and causes for violation of patterns of moisture distribution in the layered structural materials of cultural heritage objects.

Materials and methods. The presented study includes the results of tests conducted by the authors using more than 2500 samples of materials from 24 architectural monuments of different periods and locations.

Results. An analysis of the moisture distribution in 413 horizontal sections to a depth of 50–65 cm shows the directions of change in the moisture content and average pore size coinciding in almost half of the cases; however, this contradicts the assumed patterns. We suggest that such a violation of the patterns may be caused by the development of voids in historical structures. Due to these voids, humidity modes may develop independently in individual sections of the masonry. To test this assumption, we have assessed the void degree of materials using both direct and indirect indicators. The assessment results have showed that areas with suspected violations of moisture distribution patterns predominantly have developed voids. Moreover, an extended assessment of all materials has proved the presence of voids even in areas with a visually identified counter-flow.

Conclusions. The conducted analysis has demonstrated the pattern of moisture distribution in the layered structural materials of cultural heritage objects to be determined by developed voids rather than by the properties of materials themselves.

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