A method to recreate historic mortars applied at Norrlanda church on the Island of Gotland, Sweden (original) (raw)
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In the process of restoring a lime plaster on an old building, a lot of knowledge is needed in order to make the new plaster similar to and compatible with the old one. This work was carried out with the aim to create a method which makes it possible to recreate historic mortars. There are two important steps in the method: i) a practical data base consisting of mortars made with the application of local materials, known craftsmanship and the variation of a number of parameters was produced; ii) a combination of field studies and material analysis methods was used to investigate the structure and properties of the historic mortar. By combining field studies with microscopic studies of mortars in SEM and thin section specimens it was found to be possible to compare historic lime plaster surfaces and new reference surfaces of lime plaster on both a macroscopic and a microscopic scale. Microscopic studies using SEM give information about the type of slaked lime used in the mortar, as well in the reference as in the old mortars. Investigations of thin section specimens in an optical microscope give information about the type of lime and sand used, the mixing ratio, the working technique, the resulting pore structure of the mortar etc. In field studies old plaster surfaces and newly made reference surfaces are compared. It gives knowledge about how the mortars were built up and worked on, which tools that might have been used, how it was lime washed etc. The combination of those studies makes it possible to create restoration mortars with lime slaked as the historic lime, sand with similar particle size distribution curve and mineral composition, similar mixing ratio and pore structure. It is also possible to build up the new plaster in the same way as originally concerning layers and working technique, with similar tools and lime wash with recipes similar to historic ones. The use of the method is illustrated in a case study of the plaster restoration on the medieval church Norrlanda on Gotland, carried out in the summer of 2006.
Turkey is quite rich with historical buildings. Depending on various factors like time, increasing air pollution due to technological improvements of the present era together with insufficiency of inspection leads to the formation of damages on these buildings which are part of our historical heritage. Conservation of such buildings which are as important as historical documents should be the first and foremost target of any project. Where maintenance is insufficient, conservation and restoration attempts should replace it. What is necessary in restoration is the use of material which resembles the original material to the closest degree or, producing appropriate material which is compatible with the properties of the original material. The first dimension of the current problem is the insufficiency of resources while the second dimension stems from the lack of proper evaluation of the material to be used in conservation and restoration. This study defines the importance of mortars and plasters along with their history and the reasons of deterioration. In addition, it sets up the information flow of mortar and plaster within a systematic decision making process. The necessary experimental methods for the production of new repair mortar or plaster that can be used in determining the character analysis of original mortar and deterioration morphology are also analyzed. Thus, a method that can be used in the conservation and restoration studies is determined with this paper. r
In order to design a restoration mortar with properties and composition similar to the original mortar, it is important to analyze the historic mortar in several ways. A combination of analyses give information about the mixing ratio between binder and aggregates, chemical composition of the mortar, additives, tool marks, application technique etc. This paper shows the variations in Swedish medieval lime mortars with a high rate of binder. By analysing historic mortar with a combination of ocular investigations, microscopically studies of thin section specimens, Scanning Electron Microscopy and X-Ray Powder Diffraction, all the information needed for designing a restoration mortar, with composition and properties similar to the historic mortar, is gained.
2010
In order to design a restoration mortar with properties and composition similar to the original mortar, it is important to analyze the historic mortar in several ways. A combination of analyses give information about the mixing ratio between binder and aggregates, chemical composition of the mortar, additives, tool marks, application technique etc. This paper shows the variations in Swedish medieval lime mortars with a high rate of binder. By analysing historic mortar with a combination of ocular investigations, microscopically studies of thin section specimens, Scanning Electron Microscopy and X-Ray Powder Diffraction, all the information needed for designing a restoration mortar, with composition and properties similar to the historic mortar, is gained.
In order to design a restoration mortar with properties and composition similar to the original mortar, it is important to analyze the historic mortar in several ways. A combination of analyses give information about the mixing ratio between binder and aggregates, chemical composition of the mortar, additives, tool marks, application technique etc. This paper shows the variations in Swedish medieval lime mortars with a high rate of binder. By analysing historic mortar with a combination of ocular investigations, microscopically studies of thin section specimens, Scanning Electron Microscopy and X-Ray Powder Diffraction, all the information needed for designing a restoration mortar, with composition and properties similar to the historic mortar, is gained.
Research project on ancient and contemporary lime mortars in the walloon region (Belgium)
These studies should improve our restoration habits, which could be usefully re-oriented in order to improve practices on the restoration sites and ensure the permanence of our monuments. The main aim is to understand better the short-, medium-, and long-term behaviour of lime mortars. Some 100 formulations have been developed for laboratory testing according to various standards. A dozen "basic recipes" that should enable us to determine the main differences in their mechanical behaviour according to their composition were subjected to the standardised tests first. Taking these formulae as our starting points, it should be possible to develop other formulae that are better suited for ancient buildings. Our analyse is using a new leading-edge technology, the scratching test, developed at Polytechnic Faculty of Mons (Faculté Polytechnique de Mons). At the same time, mortar samples from buildings and vestiges of all periods from all over the Walloon Region are being collecte...
Construction and Building Materials, 2012
Mortars used in the two-color sgraffito, dated back to 17th century, have been investigated in order to fully characterize the material and to evaluate the state of its preservation. The non-destructive tests carried out ''in situ'', comprising thermal imaging and ground penetrating radar, revealed the inner structure of the decoration, which was exfoliated from the wall in ca. 90%. The obtained thermograms and the GPR scans allowed to choose sampling areas for subsequent destructive-tests, performed by means of optical microscopy, chemical analysis, granulometric analysis, X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and differential thermal/thermogravimetric analysis. The results reveal the decoration is composed of two separate coats of lime plasters: (1) the primer plaster and (2) the sgraffito plaster. Both the coats appeared to be a mixture of lime binder (aerial lime) and fine-to medium-grained sand, with addition of small amounts of brick chunks and charcoal. The latter is abundant in the sgraffito plaster, serving as a coloring agent. For elimination of plasters exfoliation, a calcareous PLM-A product of C.T.S. Italy was applied by injection. The non-destructive studies performed after this conservation demonstrates that the rehabilitation work has reestablished homogeneous structure of the sgraffito decoration.
2021
In this study the results of physico-chemical analysis for mortar and plaster specimens from Frangokastello castle in Sfakia (western Crete) and the subsequent designing of compatible restoration mortars are being presented, as part of a wider project for the sustainable management of the monument. In order to compose a compatible restoration mortar or plaster a reverse engineering process has been adopted. Primarily, a study of mortar and plaster specimens, that constitute a representative sampling from the monument, was performed. The analyses included macrosopic characterisation and microstructural examination using microscopy on samples and on fine polished cross-sections of them. Additionally, chemical and mineralogical analyses were executed including Fourier transformation infrared spectroscopy (FT-IR) and X-ray diffraction analysis (XRD). In the framework of thermal analysis, thermogravimetric and differential thermal analysis (TGA and DTA) were performed in order to obtain information regarding hydraulic components of the mortars. Finally, the granulometric curves of selected specimens were produced and contributed to the classification of samples in different groups and construction phases. Elaborating all these results and the state of the conservation, compatible raw materials were chosen, including hydraulic lime and other binder and aggregates. The designed mortars were subjected to durability tests, so that the mechanical behavior of the restoration mortar could be comparable to the historic ones. Subsequently, colouring experiments were carried out in order to approach one or more existing plasters for partial use. The result of this work aims to constitute a directive for the restoration of the monument, concerning the use of compatible mortars.
Sustainable mortars for rehabilitation of old plasters
Engineering Structures, 2016
External coatings of walls are the most exposed construction elements, and, consequently, the first ones needing maintenance, repair, rehabilitation or replacement. When old heritage buildings are considered, we must bear in mind not only the functional aspects of the coatings but also the preservation of its history. Having regard to this conditioning and the degradation of a wall covering, the first option should always be its conservation, maintenance and repair. Total replacement should only be considered as a last resort. In that case, there are two possible solutions: the reproduction of the old mortar or the production of a compatible one. Following exclusively and strictly one of the indicated ways is not viable, and so an integrated methodology must be adopted: the composition of the existing mortar must be taken into account and all of its constituents (amounts and types) must be as similar as possible. Also, the most significant functional characteristics must be reproduced. In ancient times, in the absence of natural pozzolans, ceramic milled residues were frequently used as artificial pozzolans and also as aggregates, providing some hydraulicity and durability to lime mortars. This paper presents some findings of an extensive research carried out at the University of Coimbra in which the viability of the introduction of ceramic residues into lime mortars is analysed. Some properties of the raw materials used for mortars production are analysed. Also, the results obtained in the mechanical characterization of hydraulic lime mortars with red and white clay ceramics are presented. The presented characterization provided some promising results, encouraging the development of new sustainable solutions for mortars production.