Papers by Keyword: Historical Buildings

Abstract: This paper deals with the possibilities of analysis of building materials in terms of chemical composition. Using the method of infrared spectroscopy, we can determine the organic compounds in coatings, adhesives, grout, and silicate materials. Building material characteristics have to be in accordance with the standards. However, due to external conditions, the material can degrade during its life. Observations and chemical analyses of the building materials must be performed to be able to do remediation and reconstruction of the historical building. Infrared spectroscopy was chosen as the best for qualitative analysis of organic admixtures in building materials.

Abstract: The historical building which can reflect the local history and culture of a city is the wealth of all mankind, but after the baptism of time, the historical building has been damaged by nature or man. In order to preserve the historical buildings and the culture contained therein, the damaged historical buildings need to be reinforced and restored. In this study, ABAQUS finite element software was used to simulate and analyze the reinforcement and repair effects of four kinds of damage states (mild damage, moderate damage, severe damage, and nearly collapse) of historical building walls caused by reinforced mesh cement. The results showed that in the case of mild damage, moderate damage and severe damage, the ultimate load displacement of the wall was raised in different degrees (the ultimate load and displacement were 200 kN and 4 mm respectively in case of mild damage and were 400 kN and 8 mm respectively after reinforcement; the ultimate load and displacement were 210 kN and 4 mm respectively in case of moderate damage and were 400 kN and 6 mm respectively after reinforcement; the ultimate load and displacement were 150 kN and 4 mm respectively in case of severe damage and were 375 kN and 7 mm respectively after reinforcement) and restored or even exceeded the performance of the wall without damage by using the reinforced mesh cement layer. In the nearly collapse wall, the ultimate load and displacement of the wall could be improved, but the performance of the wall could not be recovered as it was before being damaged (40 kN and 3 mm before reinforcement, and 165 kN and 6 mm after reinforcement). Reinforced reticulated concrete can be used to reinforce and repair historic buildings with mild, moderate and severe wall cracking, but it is not suitable for the reinforcement and restoration of cracked historical buildings which are nearly collapsing.

Abstract: In the last years, there has been a growing demand for renovations and redevelopment of older buildings that do not meet today's building standards. A very common problem is the insufficient, damaged or completely missing waterproofing of buildings, which leads to water (or moisture) penetration into the structure of the building, but there are several possibilities to disseminate moisture into structures. Many rehabilitation methods require mechanical intervention into the structure of the building, but we mustn’t forget the structures where these procedures cannot be used, specifically objects with a rich historical value, that are protected by the National Heritage Institute.This article is focused on suitability, functionality and possibilities of using a non-destructive method of drying historic masonry with microwave radiation. First the method of microwave drying is described in general, then its use in construction practice is explained. Following is a description of the experimental work carried out at the Faculty of Civil Engineering. Outcome of this work is comparison of effects of microwave drying on samples of masonry containing three different types of building materials. One of these samples is made of brick construction, which has reached the age of 350 years. At the end, the results of the experiment and the consequent suggested recommendations are summarized.

Abstract: The occurrence of radionuclides in the raw materials from which the building materials are made is a potential radiation risk in buildings constructed from these materials. In this study, four historical buildings were investigated regarding the natural radioactivity of the used bricks. The gamma radiation was evaluated using the measured mass activities of the most important radionuclides and expressed by the gamma indexes (Iγ) and dose rates. The results proved that the activity concentrations of ²³²Th and ⁴⁰K radioisotopes in bricks are higher than worldwide values. Even though Iγ do not exceed the recommended value (Iγ ˂ 1), the absorbed dose rate for the structures in indoor air was calculated in the range 115.94-161.44 nGy/h which is twice the global average for this parameter.

Abstract: While the matters of the moisture of external walls of historical buildings it turned out that apart from classical sources of moisture (such as capillary attraction, condensation etc.) there is another source which is often left behind – rainfall humidity which leaks to perimeter walls from the exterior. Whilst the Czech approach of standard assessment works with condensed moisture only, some foreign authors (especially those from Germany) point out a notable influence of rainfall humidity on the moisture regime of the mentioned constructions. Its amount exceeds the amount of rainfall that leaks into the construction due to diffusion by several times. The issue deserves to be examined in more detail, but the use of nanotechnology could help to solve or improve the problem. In some cases it would be possible to apply the suspension with added nanoparticles into the insulated masonry and improve the properties of masonry, which is facing to rainwater

Abstract: This paper concerns the evaluation and the validation of a heat and moisture transfer models in stone walls using in situ measurements on an instrumented wall. Firstly, a pure thermal (respectively moisture) diffusion problems are considerate, then this problem was combined with convection on the external edge of model. It is found that, despite of an uncoupled approach, the nonlinear thermal diffusive model performs quite well and reproduces perfectly the measured temperatures. It is the same for the convective-diffusive thermal problem, where the temperature on the surface wall is also reproduced quite well. An improvement of this second type problem results could be expected by taking into account the radiation. Otherwise, the both cases of moisture transfer problem (purely diffusive or diffusive-convective problem) are ill-simulated by the Kunzel’s model.

Abstract: The porticoes, together with medieval masonry towers, are the architectural element which mainly characterizes the city of Bologna, northern Italy. These porticoes, which extend all inside the city centre for a total length of almost 40 kilometres, have a high artistic and cultural relevance at the point that they are candidates as “Unesco World Heritage Site”. One of portico of highest heritage value is that next to the church of Santa Maria dei Servi, which is suffering important structural pathologies requiring urgent strengthening interventions. The ones strictly necessary to preserve the stability have been already implemented. It is known that for historical constructions appropriate strategies of interventions are to be adopted with special attention in the aspects related to the compatibility, durability, integrity of the original configuration. The aim of this paper is to identify the main criticalities and priorities of interventions. Based on the identified criticalities and priorities possible strategies of interventions are finally identified. A possible cause of the actual bad state of conservation could be related to the continues vibrations induced by the traffic. For this reason, measurements noises have been recently conducted by the Italian National Institute of Geophysics and Volcanology (INGV) in order to quantify their influence of the stress levels of the columns of the portico.

Abstract: The problem of the reconstruction of the historical building surface layers is in material compatibility. The basics of the convenient choice of materials for reconstruction is understanding some physical properties of used materials. The crucial properties are moisture and temperature induced deformation. The effect of moisture sorption on the elastic behavior of innovative plaster for renovation is investigated. The measurements are performed for moisture content from the dry state to the saturation water content and temperature range of 10 - 40°C.

Abstract: The paper describes the results of research in the field of thermal insulation plasters suitable for thermal insulation and rehabilitation of historical buildings. The aim was to develop energy-efficient, lightweight plasters, using both common and alternative binders. These were mainly materials based on lime slurry and light porous aggregates that are compatible with the original plaster and masonry materials. These materials are, given their high porosity, capillary active materials and can therefore be used in the restoration of historical buildings, which are often burdened with higher moisture.

Abstract: Salts and water may cause serious damage to historical masonries. Therefore, numerous conservation treatments have been developed by research teams for the consolidation and protection of porous building materials affected by salt attack. Here the focus is on methods for obtaining an effective desalination of historical masonry, indicating their advantages and disadvantages. It is pointed out that cellulose is a favourite material added to poultices used in desalination.