ブックタイトル「煉瓦造建造物の保存と修復」英語版

概要

「煉瓦造建造物の保存と修復」英語版

Restoration of Brick Masonry Cultural Property StructuresHirofumi IkawaAgency for Cultural Affairs, Cultural Properties DepartmentArchitecture and Other Structures Division, Specialist for Cultural Properties１. IntroductionRegarding restoration of brick masonry structures, there isa paper written by Masaharu Nakamura in 1998 (Nakamura1998). Here, the focus was on characteristics of structurescreated by brick masonry. In other words, the issues raisedwere on the physical properties of brick itself.Problems concerning structural characteristics pertain toseeking ways for maintaining the structural nature of themasonry composed of individual brick elements constructedwith pointing material, as it experiences natural disasterssuch as earthquakes or sinking of the foundation, as well asmethods of repairing damage including cracks and surfacespalling over time. On the other hand, problems related tophysical properties of the brick itself concern preventivemethods for efflorescence or freeze-thaw damage whichmay occur owing to the porous and moisture-absorbingproperties of the brick material.In this paper, the former issue will be dealt with focusingon reinforcement and repairs, and the latter on physicalcharacteristics, referring to past restoration projects ofnationally designated or registered brick masonry culturalproperties fn 1 .２．Issues Regarding Reinforcement and Repairof Brick Masonry StructuresThe problem of reinforcement and repair of brick masonrycultural properties cannot be handled without confrontingissues of assuring authenticity as a cultural property, whileat the same time securing safety in utilizing these historicstructures.The assurance of authenticity aims at paying respect toextant materials and construction techniques while seekingmethods for protection. This demands minimum interventionand reversibility (Suzuki 2012, p62 and Hasegawa 2012,p69). Therefore, it would be ideal to reinforce and repairstructures retaining as much of the original materials andconstruction as possible with the least areas disassembled,which would enable future reinforcement and repair forreexamination and additional work (Kimura 1997, p33).On the other hand, for adaptive use of structures, assuringsafety and maintenance of functions following present daystandards will be necessary (Nakamura 1998, p20 andYatani 1998, p132). Although reinforcement and repairsare undertaken necessarily, there is a range of options indeciding to what extent the building’s appearance should bechanged through restoration. For example, reinforcementto be installed as a long-term preventive measure againstearthquakes is generally designed so as not to stand outunder ordinary conditions. Cracks and misalignment inbrick walls are neatly repaired through re-laying of bricks.As a result, standards for authenticity cannot be said to beconstant.For these reasons, architectural conservators havethought deeply on seeking methods to reinforce andrepair structures while protecting their values as culturalproperties. Therefore, the following sections will refer topast dissertations on reinforcement and restoration to sortout merits and issues in the different ways conservators havehandled the matter, and trace the history of their struggles.Although patented methods and costs will not be discussedhere due to unavailability of reliable data, they are importantaspects to look into in selecting methods for restoration.Also, in most cases, multiple methods have been adoptedfor restoring a single structure. Therefore, it needs to befirstly noted that one structure cannot always be matchedwith a single reinforcement and repair method.３．Reinforcement of Brick Masonry CulturalProperty Structures３.１. Reinforcement with Reinforced ConcreteThis is a method of applying reinforced concrete onto theinterior wall for increased earthquake resistance. (There arecases where walls of the extant brick masonry structure arepresumed not to contribute to structural strength.)One merit of this method is that it also provides fireprotection, while on the other hand, the interior floor areabecomes smaller, the reinforced wall becomes heavier,and there is possibility of concrete carbonation requiringreplacement of the concrete material in the long term. Also,when rainwater penetrates into the reinforced concretewall, salts may appear and form efflorescence on the surface22 Chapter 3 Restoration of Brick Masonry Cultural Property Structures