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- Malaga, Katarina
(författare)
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Effekten av impregnering och klotterskydd är oklar
- 2009
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Ingår i: Husbyggaren. - 0018-7968. ; 51:5, s. 36-38
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Klotter kostar runt en miljard årligen. Ett problem är att det saknas testmetoder för att avgöra om ett klotterskydd är effektivt mot klotter och smuts på en viss typ av yta. Inom kulturvård används impregnering för att förstärka byggnadsmaterial.
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- Schouenborg, Björn, et al.
(författare)
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Duarability of Marble Cladding - A Comprehensive Literature Review
- 2007
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Ingår i: Journal of ASTM International Vol 4 No 4. ; 4, s. 19-
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Tidskriftsartikel (refereegranskat)abstract
- Natural stone has been used for centuries as building material. In historical time it was mainly used as load bearing elements, but within the past 50 years a new processing technique has made it commercially feasible to produce and use thin façade cladding. Unfortunately, a number of marble facades on buildings in both Europe and elsewhere have had serious problems with deterioration of the stone material. The TEAM _TEAM _ TEsting and Assessment of Marble and limestone_ project consortium represents nine European countries and comprises 16 partners, representing stone producers and trade associations, testing laboratories, standardization and certificate bodies, consultants, building owners and caretakers and producers of fixing and repair systems. The project had a budget of approximately 5 million dollars and was partly funded by the European Commission under the contract no. G5RD-CT-2000-00233. Two of the main objectives in the TEAM project were: — To understand and explain the mechanisms of the expansion, bowing, and loss of strength leading to degradation of marble and limestone clad facades. —To prevent the use of deleterious marble and limestone by introducing a draft for new European standards. This paper presents some of the important conclusions drawn from a literature review carried out within the TEAM project—and was based on an extensive review of literature on marble and limestone deterioration dating from the late 1800s to 2006 and the results of the TEAM project. The comprehensive information from more than 70 selected literature references is reviewed and discussed in order to describe the present knowledge on the causes and mechanisms responsible for the bowing and strength loss of thin marble cladding. In the following, the literature and TEAM findings are grouped under a number of headings proposed to explain observations. Thus, the information from the literature is compared and supplemented with the results from the TEAM project in order to present a good overview of the existing, most relevant, knowledge in the field. The literature review reveals that only few researchers have examined the durability problem from a broad perspective. In addition, no conclusive answer about the mechanisms and influencing factors can be given. The TEAM project has made it possible to identify several of the key influencing factors in marble degradation, the relative importance of various factors, and to gain a deeper understanding of the mechanisms involved.
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- Schouenborg, Björn, et al.
(författare)
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Testing and Assessment of Marble and Limestone (TEAM) - Important Results from a Large European Research Project on Cladding Panels
- 2007
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Ingår i: Journal of ASTM InternationalPaper ID JAI 100855. ; 4, s. 14-
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Tidskriftsartikel (refereegranskat)abstract
- The use of natural stone as facade cladding has been shown to have much lower life cycle costs and they are more environmentally friendly than comparable products of concrete, glass, and steel. Promoting the use of natural stone has therefore a great positive impact on the environment. However, the number of occurrences of bowing and expansion of marble and limestone panels has led to increased maintenance costs, significant safety risk, and negative publicity. The lack of knowledge of a solution to the problem of bowing marble has a large negative effect on the entire stone trade. In response, short-sighted and less durable construction solutions are used as an alternative, adding to the decreasing export figures and numbers of employees within the stone sector. The TEAM _TEAM_TEsting and Assessment of Marble and limestone_ project addresses a problem with marble types, from several European countries, that display bowing on facades in both cold and warm climates. There is, therefore a need to develop harmonized European standards for differentiating between marble that is susceptible to bowing and marble that is not. Resolution No. 013, in May 1999 taken by the European Committee for Standardization _CEN_, Technical Committee _TC_ 246 Natural Stone states the urgent needs “to develop a direct test method of the bowing risk for marble cladding products.” Thus, the project addresses the mandate for external wall coverings and the safety of panels. This paper serves to give a comprehensive overview of the main findings in the project. The main objectives were: • To understand and explain the mechanisms of the expansion and loss of strength, probably the most important phenomena leading to degradation of marble and limestone clad facades. • To prevent the use of deleterious marble and limestone by introducing drafts for European standards. • To develop a concept for assessment of facades, including a monitoring system in order to predict strength development and improve safety and reliability. • To analyze if surface coating and impregnation could prevent or diminish the degradation. • To address quality control aspects in order to optimize the production conditions. The TEAM project consortium, representing nine EU _European union_ countries, comprised sixteen partners representing stone producers and trade associations, testing laboratories, standardization and certification bodies, consultants, building owners and caretakers and producers of fixing and repair systems. A state-of-the-art report has been written and is based on an extensive compilation of more than 400 papers on marble and limestone deterioration dating from the late 1800s to 2006. A survey of about 200 buildings has given a clear picture of the extent of the problem in geographical, geological, and climatological terms. Detailed case studies of six buildings have resulted in a methodology for assessment of facades including monitoring system and risk assessment. Research both in the laboratory and the field were performed on a large number of different stone types from different countries and used in different climates. This gave the explanation of degradation mechanisms and led to the determination of the critical influencing factors. Two tests methods, including precision statements: one for bowing _1_ and one for thermal and moisture irreversible expansion have been prepared for submission to CEN TC 246. Repair techniques based on the use of surface coating and impregnation systems has been tested at laboratory and in the field. Positive side effects including increased durability and easier cleaning have been observed. Guidelines for production and product control have been proposed, and an instruction for stone sampling and description has been developed.
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