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

【Case 2：Tokyo Station, Marunouchi Main Building】Name：Tokyo Station,Marunouchi Main BuildingConstruction year：Taisho 3（1914）Structure：Steel and brick construction,two-storied, partially three-storied,slate roofBuilding area 7,821.39m2Location：1-1-3 Marunouchi, Chiyoda Ward,TokyoProprietor：East Japan Railway CompanyDesignation/Registration（date）：Important Cultural Property（2003.05.30）Restoration period2007 ? 2012? Restoration planningThe exterior wall of Tokyo Station is mostly made of the three materials of facingbrick, granite, and man-made stone, with facing brick accounting for the highest ratioof all. Prior to restoration, sounding tests were made on the walls in which crackswere observed, so that methods for preservation and restoration could be studied. Theconditions of the facing brick were grouped into nine stages (chart 5-1) fn 24 and fiveinjection methods for repairing cracks (chart 5-20) were studied, but in the end, nonewere adopted as the bricks were either replaced or left as is fn 25 .? Restoration MethodTo minimize the number of facing bricks to be replaced, the area to have extant bricksremoved was decided upon according to the extent of damage (figures 5-4, 5-5). Thelayer beneath the facing bricks is made of structural brick masonry in which every othercourse is protruded to create a stepped surface. In replacing the facing brick, these stepswere chipped off to obtain uniform surfaces to adhere the bricks onto.Facing bricks that had become loose from the substrate were treated in the followingareas by pinning fn 26 . The pins used were stainless steel full-thread screws (with nail headcovers) of 3mm diameter and 90mm in length. In areas where irregular sounds wereobserved for a vertical length exceeding 1m (15 courses in facing brick), every otherbrick in the horizontal direction every 15 courses was pinned (figure 5-3). Treatmentswere differed for the original materials and newer materials; in areas with facing bricksreplaced prior to this restoration, 32 pins were installed every 1 square meter.figure 5-3 The area of pinning of facingbricks（The area of loose facing bricks isshown in the blue lines.）（Reference：重要文化財東京駅丸の内駅舎保存・復原工事報告書）chart 5-1chart 5-2? OverviewTreatment of bricks according to their conditions (preservation or removal)Repair methods for cracked bricksFollowing detailed inspections executed beforehand to confirm the damage conditionof bricks, limited areas with cracked bricks were treated with brick replacement or thosewith bricks detached from the substrate were pinned. Crack repair employing injectionmethods would have enabled further decrease in areas of brick replacement.no.group of bricksconditionpreserve/remove1original materialfine textured. no chippingpreserve2original material + abnormal soundabnormal soundpreserve(hammering test method)3original material + spallingsurface deterioratiion due toremovespalling4original material + crackcracked facing brickremove5 original material + soiling soiling on the surface preserve6 original material + efflorescence efflorescence on the surface preserve7original material + incomplete repair (-2006)painted on the spallingremovesurface8original material + complete repair (-2006)not applicablenot applicable9original material + incomplete repair (-2006)replaced with bricks ofdifferent colors andtexturesremovecracked facingbricksmaterial/method epoxy resin inorganic materialtoolabsorptionproperty of brickslow-pressurelow-pressure feeding instrumentmedium viscosity high viscosity ultra fine cement grout Non-shrinkage cementhigh-pressurehand grease gun hand grease gun manual injection pump manual injection pumpa part of thestructural brickwas cut offfigure 5-4 Flow chart of replacement of facing bricks to beremoved（sectional plan）low absorptionlow absorptionno absorptionhigh absorption, requiring preventive measures beforeinjectioncrack width 0.3? 0.5mm 0.4? 3.5mm 0.6? 4.0mm 0.2? 2.0mm 4.0? 6.0mmfilling ability△△◎△○filling defect. the plannedinjection volume is notreachedpartial hardening failureof adhesive due topenetration into brickpenetration into deep f i l l i n g d e f e c t mostly filled (some penetrationinto bricks)narrow cracks can be (penetration into bricks)achievedworkability○◎◎△△strengthdevelopmentrequires exchange of cylindercomponentーーrequires two water washings requires three waterand injection of absorption washings and injectioncontrolling agent to the of absorption controllingcrack prior to treatment agent to the crack prior totreatment△○◎△△partial hardening failure ofadhesive due to penetrationinto brickーーpartial hardening failure of partial hardening failureadhesive due to penetration of adhesive due to penetrationinto brickintobrickcrackreplaced facingbricksfacing bricksto be removedfigure 5-5 Areas ofbrick replacement ofcracked facing bricks（elevation plan）97