ARTICLE IN PRESS G Model CULHER-3890; No. of Pages 14 Journal of Cultural Heritage xxx (xxxx) xxx–xxx Available online at ScienceDirect www.sciencedirect.com Original article Research into the influence of subsoil on sulphates, nitrates and chlorides accumulated in renovation plasters used for rehabilitation of monuments in the Czech Republic Martina Peˇ rinková a , Ivona Dlábiková a,∗ , Pavel Pospíˇ sil b , Vlastimil Bílek c a Technical University of Ostrava, Faculty of Civil Engineering, Department of Architecture, Ludvíka Podéˇ stˇ e 1875/17, 708 33 Ostrava – Poruba, Czech Republic b Technical University of Ostrava, Faculty of Civil Engineering, Department of Geotechnics and Underground Engineering, Ludvíka Podéˇ stˇ e 1875/17, 708 33 Ostrava – Poruba, Czech Republic c Technical University of Ostrava, Faculty of Civil Engineering, Department of Building Materials and Diagnostics of Structure, Laboratory of Building Materials, Ludvíka Podéˇ stˇ e 1875/17, 708 33 Ostrava – Poruba, Czech Republic a r t i c l e i n f o Article history: Received 3 June 2020 Accepted 28 January 2021 Available online xxx Keywords: Renovation plasters Historical masonry Masonry salinity Sulphates Subsoil a b s t r a c t Degradation of historical masonry and plasters is often caused by external conditions; the presented research focused on salts originating from subsoils. The content of salts: Sulphates, Nitrates and Chlorides was analysed from plasters on 5 chosen historic buildings before and after the renovation in this paper. The samples were collected three times between 1998−2018. In some cases, the Sulphates were still present or even with a higher content after the renovation in comparison with the state before renovation. That can be caused by many factors from environment and this work focused on source from the subsoil. To understand better geological background the borehole data around each object were studied. According boreholes were buildings divided in two groups: on clayey subsoil and building on subsoil without clay. By Kruskal–Wallis test was proved, that the Sulphates content in plasters was constant before and after the renovation on clayey subsoils, it didn´ t changed in a time. On subsoils without clay (mainly silty to sandy soils) the content of Sulphates declined after the renovation, what was proved by regression analyse on 95% confidence level. © 2021 Elsevier Masson SAS. All rights reserved. 1. Introduction The issue of damage to historical masonry by salt crystalliza- tion in the pore systems of artificially made ceramic materials, natural stones or plasters has long been known as it affects his- torical buildings. The salts usually originate from the subsoil, from where they naturally migrate in solutions. Movement of the saline solutions depends on many factors. The essential aspect is the chemical composition of the salts, which determines their solubil- ity, migration and conditions of crystallization in case of decreased humidity/moisture. From the geochemical point of view, the pro- cess is affected by the composition of a subsoil structure; from the hydrogeological point of view, the groundwater level and the nature of the subsoil’s pore system in the capillary fringe above ∗ Corresponding author at: Mateja Bela, 8768/28, 01015 ˇ Zilina, Slovakia. E-mail addresses: martina.perinkova@vsb.cz (M. Peˇ rinková), ivona.dlabikova@gmail.com (I. Dlábiková), pavel.pospisil@vsb.cz (P. Pospíˇ sil), vlastimil.bilek@vsb.cz (V. Bílek). groundwater level and in the aerated zone dominate, and humidity varies depending on the amount of rainwater falling on the ground in the broader proximity of the structure. Many authors have dealt with the degradation process of his- torical masonry, e.g., Winkler [1] provided a complex assessment of the degradation of natural stones in historical structures, Goudie and Viles [2] and Rodriguez-Navarro and Doehne [3] focused on the effect of various types of salts on construction materials, while Laue [4] assessed material erosion due to the effect of salts in relation to the climate in which the structures are located. The most harmful salts are often highly soluble in water and are transported by water inside porous material [5]. WTA specifies the classification of the salt content in the material at three levels: low, medium and high [6,7]. Damage to porous construction material is usually caused by physical and chemical processes (especially crys- tallization pressure). The process is linked to decreased moisture of the porous material and fluctuation of relative air humidity in prox- imity to the structure. This results in a transition from liquid to solid salt state, i.e., in crystallization. Restoration procedures to renovate and protect porous materials affected by salt-related degradation https://doi.org/10.1016/j.culher.2021.01.011 1296-2074/© 2021 Elsevier Masson SAS. All rights reserved. Please cite this article as: M. Peˇ rinková, et al., Research into the influence of subsoil on sulphates, nitrates and chlorides accumulated in renovation plasters used for rehabilitation of monuments in the Czech Republic, Journal of Cultural Heritage, https://doi.org/10.1016/j.culher.2021.01.011