Abstract
In this paper, we analyze the state of conservation of ceramic building materials (clay masonry units) containing a large share of waste materials in the form of ash and slag from coal combustion and sawdust from wood processing, operated for several decades in facing walls of religious buildings, in external environment conditions. For the purpose of this analysis, comparative tests were carried out on the samples of ceramic materials cut out from facing walls and samples extracted from the same ceramic materials; they were stored in laboratory conditions for the entire time. The following were investigated: initial water absorption, capillary rise, and porosity structure determined with mercury intrusion porosimetry (MIP). The research has shown, among other things, that the ceramic materials exploited in the external environment are characterized by an almost twofold increase in the initial rate of water absorption and by a different size of dominant pores and a pore size distribution in comparison with ceramic materials stored in laboratory conditions. The results, obtained for ceramic building materials (clay masonry units) containing the above-mentioned waste materials in their composition, constitute a novelty. They fill a gap in the literature by establishing how decades-long operation in natural conditions affected the capillary properties and the porosity structure of the ceramics under investigation. Based on the obtained research results, conclusions of cognitive and practical significance have been formulated that relate to the possibility of the exploitation of facing walls made of investigated ceramic materials.
Highlights
Many buildings, including historic structures, have external facing walls made of traditional ceramic building materials that feature high durability
Facing walls in a significant number of buildings, including religious structures, erected in the second half of the previous century, especially in central Poland, were made of clay masonry units containing a large share of waste materials
For the production of the ceramic building materials that are the subject of this study, we used a molding sand consisting of Pliocene clays with a percentage fraction content as in Table 1 and chemical analysis as in Table 2, ash–slag mixture where particle size analysis is given in Table 3, and wood sawdust
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. That time, building materials were used for building facing building materials in the literature [8] Some guidelines in this respect are contained in walls, despite the lack of tests and manufacturer’s declarations related to their durability the study [9], where the maximum amount of water absorption of ceramic masonry units in external environment conditions. The results of the study, which are new and compared with the results obtained for the reference ceramic building materials stored for the same period of time in laboratory conditions, will be of great practical importance They will provide an answer to the question of whether facing walls made of this type of ceramic materials in many buildings in the second half of the previous century can still be used without any changes or whether they should be treated with surface protection, which, according to [10] is, e.g., plaster coating
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