Physical and mineralogical changes of Hungarian monumental stones exposed to different conditions: stone-testing in-situ and under laboratory conditions

The Székesfehérvár Ruin Garden is a unique assemblage of monuments belonging to the cultural heritage of Hungary due to its important role in the Middle Ages as the coronation and burial church of the Kings of the Hungarian Christian Kingdom. It has been nominated for “National Monument” and as a consequence, its protection in the present and future is required. Moreover, it was reconstructed and expanded several times throughout Hungarian history. By a quick overview of the current state of the monument, the presence of several lithotypes can be found among the remained building and decorative stones. Therefore, the research related to the materials is crucial not only for the conservation of that specific monument but also for other historic structures in Central Europe. The current research is divided in three main parts: i) description of lithologies and their provenance, ii) physical properties testing of historic material and iii) durability tests of analogous stones obtained from active quarries. The survey of the National Monument of Székesfehérvár, focuses on the historical importance and the architecture of the monument, the different construction periods, the identification of the different building stones and their distribution in the remaining parts of the monument and it also included provenance analyses. The second one was the in situ and laboratory testing of physical properties of historic material. As a final phase samples were taken from local quarries with similar physical and mineralogical characteristics to the ones used in the monument. The three studied lithologies are: fine oolitic limestone, a coarse oolitic limestone and a red compact limestone. These stones were used for rock mechanical and durability tests under laboratory conditions. The following techniques were used: a) in-situ: Schmidt Hammer Values, moisture content measurements, DRMS, mapping (construction ages, lithotypes, weathering forms) b) laboratory: petrographic analysis, XRD, determination of real density by means of helium pycnometer and bulk density by means of mercury pycnometer, pore size distribution by mercury intrusion porosimetry and by nitrogen adsorption, water absorption, determination of open porosity, DRMS, frost resistance, ultrasonic pulse velocity test, uniaxial compressive strength test and dynamic modulus of elasticity. The results show that initial uniaxial compressive strength is not necessarily a clear indicator of the stone durability. Bedding and other lithological heterogeneities can influence the strength and durability of individual specimens. In addition, long-term behaviour is influenced by exposure conditions, fabric and, especially, the pore size distribution of each sample. Therefore, a statistic evaluation of the results is highly recommended and they should be evaluated in combination with other investigations on internal structure and micro-scale heterogeneities of the material, such as petrographic observation, ultrasound pulse velocity and porosimetry. Laboratory tests used to estimate the durability of natural stone may give a good guidance to its short-term performance but they should not be taken as an ultimate indication of the long-term behaviour of the stone. The interdisciplinary study of the results confirms that stones in the monument show deterioration in terms of mineralogy, fabric and physical properties in comparison with quarried stones. Moreover stone-testing proves compatibility between quarried and historical stones. Good correlation is observed between the non-destructive-techniques and laboratory tests results which allow us to minimize sampling and assessing the condition of the materials. Concluding, this research can contribute to the diagnostic knowledge for further studies that are needed in order to evaluate the effect of recent and future protective measures.

The Effect of Preservative Interventions on the Chemical- Physical and Structural Characteristics of Panel Painting

This work studies the impact of two traditional Romanian treatments, Red Petroleum and Propolis, in terms of real efficiency and consequence on the wooden artifacts. The application of these solutions is still a widely adopted and popular technique in preservative conservation but the impact of these solutions is not well known. It is important to know the effect of treatments on chemical-physical and structural characteristics of the artifacts, not only for understanding the influence on present conditions but also for foreseeing the future behavior. These treatments with Romanian traditional products are compared with a commercial antifungal product, Biotin R, which is utilized as reference to control the effectiveness of Red Petroleum and Propolis. Red Petroleum and Propolis are not active against mould while Biotin R is very active. Mould attack is mostly concentrated in the painted layer, where the tempera, containing glue and egg, enhance nutrition availability for moulds. Biotin R, even if is not a real insecticide but a fungicide, was the most active product against insect attack of the three products, followed by Red Petroleum, Propolis and untreated reference. As for colour, it did not change so much after the application of Red Petroleum and Biotin R and the colour difference was almost not perceptible. On the contrary, Propolis affected the colour a lot. During the exposure at different RH, the colour changes significantly at 100% RH at equilibrium and this is mainly due to the mould attack. Red Petroleum penetrates deeply into wood, while Propolis does not penetrate and remains only on the surface. However, Red Petroleum does not interact chemically with wood substance and it is easy volatilized in oven-dry condition. On the contrary Propolis interacts chemically with wood substance and hardly volatilized, even in oven-dry condition and consequently Propolis remains where it penetrated, mostly on the surface. Treatment by immersion has impact on wood physical parameters while treatment by brushing does not have significant impact. Especially Red Petroleum has an apparent impact on moisture content (MC) due to the penetration of solution, while Propolis does not penetrate so much and remains only on surface therefore Propolis does not have so much impact as Red Petroleum. However, if the weight of the solution penetrated in wood is eliminated, there is not significant difference in MC between treated and untreated samples. Considering physical parameters, dimensional stability is an important parameter. The variation of wood moisture content causes shrinkages/swelling of the wood that polychrome layer can only partially follow. The dimension of wooden supports varied under different moisture conditioning; the painted layer cannot completely follow this deformation, and consequently a degradation and deterioration caused by detachment, occurs. That detachment affects the polychrome stratification of the panel painting and eventually the connections between the different layer compositions of the panel painting.

Stone architecture in Carso plateau. Settlement patterns and construction techniques of historic buildings

The use of stone and its types of processing have been very important in the vernacular architecture of the cross-border Carso. In Carso this represents an important legacy of centuries and has a uniform typological characteristic to a great extent. The stone was the main constituent of the local architecture, setting and shaping the human environment, incorporating the history of places through their specific symbolic and constructive language. The primary aim of this research is the recognition of the constructive rules and the values embedded in the Carso rural architecture by use and processing of stone. Central to this investigation is the typological reading, aimed to analyze the constructive language expressed by this legacy, through the analysis of the relationship between type, technique and material.