Deterioration mechanisms of building materials of Jiaohe ruins in China

Almost all defects of earthen buildings such as roughening, erosion, volume reduction, cracking as well as crazing, etc., have been witnessed in the ancient city of Jiaohe, an earthen architectural heritage in northwest China. In this paper, their long-term durability and deterioration due to prolonged exposure to environmental factors were studied, based on the basis of field investigation and laboratory analysis. The results indicated that the deterioration of building materials should be attributed to their basic properties, including density, particle size distribution, soluble salts, mineral, mechanical strength, etc., and interaction with environmental factors. And then, four main deterioration modes can be identified, namely: wind-related deterioration, water-related deterioration, temperature-related deterioration and chemical related deterioration. It can be concluded that the greatest deterioration was wind-related deterioration on west-north facing façades, and chemical related deterioration on the surface of building materials.     

Effectiveness of crystallization inhibitors in preventing salt damage in building materials

Salt crystallization in porous materials constitutes one of the most frequent causes of decay of buildings in a wide range of environments. Up to now no definitive solution exists to limit salt crystallization damage, unless of removing either the salt or the moisture. The possibility of making the process of salt crystallization less harmful by means of crystallization inhibitors has only recently been considered. Crystallization inhibitors are known to delay nucleation and to modify the growth rate of the crystals in bulk solution, but their possible application for the prevention of salt decay in porous material is still controversial.The present paper reports a series of systematic investigations performed on three different materials (a limestone, a sandstone and a brick) contaminated with two types of salt (sodium chloride and sodium sulphate) and two types of inhibitors (sodium-ferrocyanide and diethylenetriaminepentakis methylphosphonic acid). Drying experiments have been performed to study the effect of the inhibitors on the salt solution transport. Accelerated crystallization experiments have investigated the possible consequences of the application of the inhibitor on salt crystallization damage (quantified as material loss).Environmental Scanning Electron Microscope (ESEM) has been used to study how the presence of inhibitors affects the crystallization morphology of salt in the material.The results show that the effect of the inhibitor strongly depends on the type of substrate. NaFeC, when applied on NaCl contaminated limestone and brick was able to enhance the drying and to favour the appearance of efflorescences, whereas the effect on the sandstone was very limited. DTPMP enhanced the drying of Na₂SO₄ laden sandstone, but had no influence on the drying of both brick and limestone. These different have been attributed to the properties of the materials, in particular pore size distribution and composition.The effects of the inhibitor on salt crystallization damage were less evident: no differences in surface damage, quantified as material loss, were observed between specimens with and without inhibitor.     

Silicatescape – preserving building materials in the old urban center landscape: The case of the silicate brick and urban planning in Tel Aviv-Jaffa

In November 20th 2007 Tel Aviv-Jaffa Municipality confirmed its list of buildings earmarked for conservation. The confirmation was related only to Tel Aviv cultural heritage, the city that was founded in 1909, along the Mediterranean seashore, next to old Jaffa. The list was published 4 years after part of the old urban center of Tel Aviv was nominated as World Heritage Site for its architectural uniqueness (Tel Aviv the White City). The list and the nomination were focused on architectural styles, which are based on building material, the silicate brick, used in Israel throughout the years 1918–1948. This building material and technology left its imprint on Tel Aviv's landscape and is also a part of Tel Aviv's history and development. In spite of its importance, all concerned in Tel Aviv-Jaffa municipality and urban planning, have totally ignored this phenomenon.The thrust of this discussion is that the silicate bricks phenomenon, a building material and technology, due to its importance to Tel Aviv heritage and its vast distribution in Tel Aviv landscape, should be integrated into the current urban renewal development process in the old city of Tel Aviv. The discovery of its history and its role in Tel Aviv cultural heritage will change the attitudes of Tel Aviv-Jaffa municipality to this building material; instead of a vernacular phenomena, a common brick or a frequent building technology, it will get a better appreciation. Urban landscapes of many cities around the world are based on vernacular phenomena, which are ignored by the urban municipalities. The silicate case should serve as an example of the role of a vernacular heritage, and in this case a common building material, in the urban renewal and conservation process.     

A methodological approach in the evaluation of the efficacy of treatments for the dimensional stabilisation of waterlogged archaeological wood

The aim of the work is to set up a methodological approach to verify the effectiveness of the treatments of decayed waterlogged archaeological wood and to point out the proper thermo-hygrometric conditions for its preservation after treatment. The treatments were performed on wood samples of maritime pine (Pinus pinaster Aiton), oak (Quercus sp. caducifolia), elm (Ulmus cf. minor) and strawberry tree (Arbutus unedo L.), obtained from stems pertaining to the original vegetation found in the excavation site of the Ancient Ships in Pisa (Italy), and dated from seventh century BC to second century AD The utilised products were: Polyethylene Glycols (PEG) of various molecular weights, a Polypropylene Glycol (PPG 425), Trehalose (α-D-glucopyranosyl-α-D-glucopyranoside), and their mixtures, and also a Hydroxypropylcellulose (Klucel). The main objective to be pursued by the treatments was considered the stabilisation of the original size and shape of samples. The various steps of this approach were: the execution of a preliminary diagnostic survey on untreated samples; the characterisation of treatment solutions ‘as such’ to establish the property to be monitored during the treatment; the evaluation of the main physical characteristics of wood after the treatment were determined. Among the latter, the coefficient of dimensional stability during the exposure to a series of selected thermo-hygrometric conditions and the retention of consolidants after the treatment. These two measurements allowed the definition of the ‘efficacy of a treatment’, φ_T, a new parameter firstly utilised in this work. It measures the stabilisation capability of the percent unit of retained product, and its value permits to put in evidence the consolidants that stabilise wood with the lowest amount of product. Conversely, it was not possible to measure the Anti-Shrink Efficiency (ASE), one of the most utilised parameters for the evaluation of treatments, because of the serious distortions and fractures observed in all the heavily degraded untreated samples.     

Study of fire-extinguishing performance of portable water-mist fire extinguisher in historical buildings

This paper describes both theoretical and experimental studies on the application of a portable water mist extinguisher in suppressing flammable liquid and wood crib fires. At first, the interaction between water mist and fire plume is studied by analyzing the instantaneous process of fire extinction. And then, the feasibility in extinguishing diesel oil, gasoline and wood crib fires is studied by a series of experiments. Theoretical analysis and experimental results show that the extinguishing mechanisms and process change with the difference of water mist characteristics (such as water flux density, droplet velocity and diameter), and the portable water mist fire extinguisher with appropriate characteristics was able to extinguish Class A and Class B fires. It is a potential fire protection means for historical buildings.     

Microclimate inside a semi-confined environment: Valuation of suitability for the conservation of heritage materials

The microclimatic analysis of the Petrarca's tomb in Arquà Petrarca, Padua (Italy) was performed to assess the suitability of a closed environment located outdoors respect to the conservation requirements of heritage materials. Results showed that the thermo-hygrometric conditions inside the tomb were not suitable for the conservation of organic materials, like bones and wood. The orientation (north or south) was the main responsible for the different damage features of the two sides of the wooden case housing the human remains inside the tomb. Technical solutions were finally implemented to improve the conservation conditions, thus avoiding further damage.     

Identification of the materials used in an Eastern Jin Chinese ink stick

Chinese ink stick has a long history and a special importance in the Chinese culture. For the first time, Pyrolysis Gas Chromatography and Mass Spectrometry (Py-GC/MS) was used to identify the materials in an ancient Chinese ink stick. Four types of constituents could be detected in the archaeological ink stick of the Eastern Jin period (317–420 AD): (1) borneol (Chinese name bing piàn); (2) compounds related to essential oil or tar of conifer wood: cedrene, aromadendrane, cedrane, cuparene, cedrol, retene, methyl dehydroabietate and 9-methyl retene; (3) marker compounds from animal glue; (4) polycyclic aromatic hydrocarbons (PAHs) from soot. The information obtained through this study provides conclusive evidence for use of additives of borneol and cedar oil, binding media of animal glue and pine wood soot in the ancient ink stick.     

The contribution of urban-scale environmental monitoring to materials diagnostics: A study on the Cathedral of Modena (Italy)

The problem of environmental monitoring aimed at identifying and evaluating the weathering mechanisms affecting historical stoneworks is here discussed and a methodology based on the use of already available, long record, urban-scale environmental data is proposed. An example of its application to the Cathedral of Modena (Italy, XII-XIV century, included in the UNESCO's World Heritage List) is then presented. In this case, the methodology allowed the identification of the main degradation causes, which found significant confirmation by material diagnostics on the available samples and finite element structural modelling. Thanks to the decay causes identification allowed by the proposed methodology, more effective restoration procedures can be outlined.     

Definition of the procedure to determine the suitability and durability of an anti-graffiti product for application on cultural heritage porous materials

Anti-graffiti protection is becoming a common practice in many urban buildings, especially in areas of social decay. When Cultural Heritage objects are affected by graffiti, the application of anti-graffiti products can result not only in an unsatisfactory result but also in an irreversible damage of an invaluable cost. The materials commonly found in these constructions are very frequently porous and present different types of decay forms. For this reason, the protection of these materials should be carefully considered. This paper proposes a criterion to decide on the suitability and durability of an anti-graffiti product prior to its application in a porous surface of a protected building. Performance classifications are defined for a series of properties including colour and gloss, and hydric and durability properties, and minimum acceptable values or reductions in these properties are recommended.     

Secondary phosphates in the ceramic materials from Frattesina (Rovigo,North-Eastern Italy)

The pervasive crystallization of secondary phosphates in pores and fractures of numerous potsherds from the archaeological site of Frattesina (Fratta Polesine, Rovigo – North-East Italy) indicates that contamination occurred after burial. The chemical composition of these phases, which are Mg-rich vivianite and mitridatite, shows that sources of phosphorus, calcium, iron and magnesium were locally available and that the precipitation and diagenesis of these minerals were strongly influenced by micro-environmental conditions within the archaeological deposit.     

Degradability of building stone: Influence of the porous network on the rate of dissolution of carbonate and evaporitic rocks

The susceptibility to weathering of eleven carbonate and evaporitic Spanish building rocks was studied by means of dissolution experiments. Mineralogy, petrology, geochemistry and porosity of the rocks were also characterized in order to determine the potential relationships between these properties of the rocks and their dissolution rates. Rock slabs were submerged in a 0.1 M HCl acid solution for 72 h and the amounts of Ca, Mg and S released were measured, as well as the weight loss of the samples during the acid attack. Alabasters, which presented very low porosity, were dissolved to a lesser extent than limestones and dolostones in the time of the experiment. A significant positive correlation was found for connected with the weight loss of the rocks during dissolution and with the kinetic rate of Ca dissolution. Overall, the results highlight the influence of the porous network in the degradability of building stones by controlling their rate of dissolution. There is a positive correlation for all the rocks between weight loss along acidic attack and connected porosity, but no relationship between mineralogical and petrographical composition and susceptibility to dissolution.     

Unusual differential erosion related to the presence of endolithic microorganisms (Martvili,Georgia)

The presence of a diffuse biodeterioration phenomena can be observed across large areas of the outer surface of the limestone walls of the Church of the Virgin in Martvili. A differential erosion phenomenon was detected, suggesting a possible association with biological colonization. The erosion phenomenon is characterized by a circular discoloration leading progressively to the detachment of flakes of limestone at its center. Since the aforementioned process has not been described in the literature until now, the present study was focused on the interpretation of its origin and evolution. Three sides of the Church are affected by a variety of occurrences of circular differential erosion which display different stages of the process, whereas the western side is affected by epilithic growths across its entire surface. Surveys of the petrographic, mineralogical and physical features of the stone were made, and parameters such as density and porosity were recorded. Samples were analyzed by optical microscopy and SEM analysis in order to detected the presence of microorganisms whose species were then identified by means of morphological and molecular examinations. The study of cross-sections stained using the PAS method has confirmed the causal connection between microorganisms and the deterioration phenomena, providing information about their spread of penetration into the substrate and their substantial potential for causing damage. Dryness appears to be the main ecological condition favoring endolithic rather than epilithic growth. The most common isolated microorganisms were cyanobacteria (Chroococcales) and, to a lesser extent, meristematic fungi. The characteristics of the stone, and especially some endogenous discontinuities related to the accumulation of sedimentary layers and to the action of stone carving tools, might explain why the same differential erosion phenomenon occurs in specific areas of the block stones. The development of the differential erosion phenomenon shows a variety of stages of biological colonization. The progressive evolution of the deterioration process has been observed in detail: (a) firstly, white circular discolorations appear on the stone, which darken over time eventually becoming almost black; (b) circular perforations appear around the perimeter; (c) and finally a flake detaches from the center, leaving a deep depression in the stone.     

Characterization of the organic materials used in the painting of the vaulted ceiling at the Saadian Tomb of Mulay Ahmed Al-Mansour (Marrakech)

The Saadian tombs from the era of sultan Ahmed al-Mansour (1574–1603) are beautifully decorated and have always been a major attraction for visitors to Marrakesh. The central mausoleum, named the Hall of Twelve Columns, encloses the tombs of Ahmed al-Mansour and his family. The hall has a huge vaulted ceiling, carved cedar doors, opening windows with wooden marquetry screen (Mashrabiya), and grey Italian marble columns. This paper presents the first attempt to identify the organic materials used by the Moroccan artisans. A GC/MS analytical procedure was used for the characterization of lipids, waxes, resins, pitch, tar, proteinaceous and saccharide materials in the same paint micro-sample. The analytical study identified the organic materials used in the polychrome and gilded decorations of the walls, ceiling and dome of the hall. Data showed that the polychrome decorations were painted using animal glue as a binder, and highlighted the treatment of the wall surface with linseed oil and the retouching of the paintings based on a saccharide binder. The use of a proteinaceous-resinous-oil mixture, applied on a proteinaceous preparation layer, for the gilded decorations revealed a very similar technique to that used at the time in Europe for mural paintings.     

Evaluation of the effect of phase change materials technology on the thermal stability of Cultural Heritage objects

The use of phase change materials (PCMs) in civil buildings as an effective thermal energy storage solution has been well documented in literature and proven in the field. When applied to Cultural Heritage, PCMs’ technology needs to be adapted to specific requirements. Besides the important objectives of economic return and human comfort, the indoor microclimatic conditions have to be suitable for conservation purposes. The application of PCMs’ technology to Cultural Heritage has been investigated within the European MESSIB (Multi-source Energy Storage System Integrated in Buildings) project. Firstly, several methodologies of incorporation of PCMs in different materials were studied and tested. The thermal properties of gypsum panels and silicon coatings incorporating micro-encapsulated PCMs in the form of powder and emulsion were analysed in the laboratory. Then, PCMs incorporated in gypsum panels in contact with a wooden panel were tested and their effect on the thermal behaviour of the wooden panel was evaluated under thermal cycles in a climatic chamber. PCMs incorporated in silicon coatings in contact with a painting were also tested. Moreover, gypsum panels containing PCMs were tested in the S. Croce Museum in Florence, Italy, where the microclimatic monitoring has shown thermal conditions potentially dangerous for the works of art preserved. The research performed both in the laboratory and on the field confirmed the effectiveness of the PCMs as thermal storage solutions, but also gave evidence on an important drawback when the material incorporating PCMs is in direct contact with an object of art.     

元初书家题画诗论——以赵孟頫、邓文原、鲜于枢为例

题画诗是艺术融合的典型与艺术接受的产物,它兼有诗、画、书的多重美,又体现着接受者与作者、作品之间的关系.它是诗人、画家、书家共同创作的结果,并随着文人画创作的高涨而在元代走向兴盛.在对兼有多种艺术身份的题画诗的研究中,考察书家的题画诗创作具有不可替代的意义.本文以元初赵孟烦、邓文原、鲜于枢三大书法家为例,通过深入解读其题画诗,发现展现情景意识、时间意识、空间意识分别是三家始终坚持的创作模式,这种模式源于三家分别以形神兼备、生命底蕴、景物气度为原则的绘画接受模式,并分别与三家各自以中和、韵致、骨力为特点的书法风格相一致.本文拟通过挖掘三家题画诗的诗歌创作模式、绘画接受模式和书法题画的风格以及其间的内在联系,探索题画诗创作中诗人与画家、图画之间的关系及其成因.