Environmental influences on historical monuments: a multi-analytical characterization of degradation materials

<div> <p>The Minoan Palace of Knossos and the Venetian coastal fortress “Rocca a mare” (Koules), located in Heraklion, Crete, Greece, are two important monuments for the history of mankind particularly vulnerable to environmental conditions, since they are located in an island subjected to strong variations in humidity and, as in the case of the Venetian fortress, in direct contact with sea water. In this type of surrounding environment, the formation of salt efflorescence as well as various other soluble salts crusts is a common situation. They occur according to the existing solubilization and crystallization conditions and can happen either in exterior or interior areas of the monuments. Their presence may stimulate further degradation, either due to the chemical dissolution of the substrate materials or due to the mechanical actions created by the formation of crystals, which may result in the decay of the substrate.</p> <p>A set of samples from both monuments were analysed using various laboratory (ex-situ) analytical methods such as optical microscopy (OM), X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Raman spectroscopy and Laser-Induced Breakdown Spectroscopy (LIBS). In-situ measurements using portable Raman and LIBS instruments were also performed. The comparative results from ex-situ analysis and in-situ measurements will be presented with emphasis to the chemical composition of the crusts and their origin. Results indicate that observed stalactites and salt efflorescence are directly related to the type of supporting material and the conditions of the surrounding environment. In general, the formation of crusts and salts are due to processes of alteration of the supporting material while the high impact of sea salt on the formation of the efflorescence at the Venetian coastal fortress was also confirmed.</p> <p> </p> <p>[1] This work was supported by the European Union’s Framework Programme for Research and Innovation HORIZON 2020 under Grant Agreement 700395 project HERACLES.</p> <p>Acknowledgment to the Portuguese Foundation for Science and Technology (FCT) UID/EAT/00729/2013 and EAT/00729-3 by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT—Portuguese Foundation for Science and Technology under the project number POCI-01-0145-FEDER-007688, Reference UID/CTM/50025/2013 NOVA.ID.FCT, and the PhD Scholarship SFRH/BD/145308/2019.</p> </div>

RAW CLAY MATERIALS FOR THE LIGHT-TONE CERAMIC BRICK FROM THE STANDPOINT OF VANADIUM SALT EFFLORESCENCE

Ceramic lining brick is the most eco-friendly material and it is widely spread in modern construction. To date, the brick of light colors is of particular interest among consumers (peach, straw, beige, etc.). One of the main problem of brick constructions which impair technical and aesthetical properties is the salt weathering on the ceramic masonry surface. The reasons for this phenomenon are various-high content of water-soluble salts in clay raw materials, migration of salts from cement masonry, water hardness, etc. There are plenty methods to reduce damage and protect lining brick from salt efflorescence but raw materials selection and preliminary analysis of its liability to salt weathering is of particular importance. This paper addresses to the occurrence causes and microstructure of vanadium salts on the light-tone lining brick. The mineral composition, physical and molding properties of raw clay materials from Bolshaya Karpovka, Talalaevskoe, Chasov-Yarskoe deposits is analized from the standpoint of vanadium salt efflorescence. It is found that salt formation on the test sample surface consists of alkalis sulphates and calcium vanadates from the greenish-yellow to orange colors. The paper provided recommendations for using above-mentioned clays in light-tone ceramic brick manufacturing.

Salt Corrosion of Masonry Mortar

Brickwork is one of the most convenient of enclosures. It combines supreme thermal insulation, durability, aesthetic appearance. However, masonry is subjected to plurality of destructive factors, one of which is salt corrosion. Survey of buildings of Saint-Petersburg has been described in this article. Experimental data that proves vulnerability of mortar to salt efflorescence has been obtained. Several solutions of this problem have been recommended and necessity of future researches has been stated.