1、Designation: C1722 11Standard Guide forRepair and Restoration of Dimension Stone1This standard is issued under the fixed designation C1722; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in pare
2、ntheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide describes materials and procedures for re-storing facades constructed of or finished with dimensionstone. All of the materials, procedures
3、, and principles aresuitable for restoration of historic and nonhistosric structures.1.2 This guide is not intended to address restoration ofinterior dimension stone, although many of the materials andprocedures may be suitable for interior use.1.3 The values stated in inch-pound units are to be reg
4、ardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the use
5、r of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory requirements prior to use.2. Referenced Documents2.1 ASTM Standards:2C5 Specification for Quicklime for Structural PurposesC10 Specification for Natural CementC91 Specification for
6、 Masonry CementC119 Terminology Relating to Dimension StoneC141 Specification for Hydraulic Hydrated Lime for Struc-tural PurposesC150 Specification for Portland CementC207 Specification for Hydrated Lime for Masonry Pur-posesC270 Specification for Mortar for Unit MasonryC1180 Terminology of Mortar
7、and Grout for Unit MasonryC1242 Guide for Selection, Design, and Installation ofDimension Stone Attachment SystemsC1324 Test Method for Examination and Analysis of Hard-ened Masonry MortarC1329 Specification for Mortar CementC1489 Specification for Lime Putty for Structural PurposesC1515 Guide for C
8、leaning of Exterior Dimension Stone,Vertical And Horizontal Surfaces, New or ExistingC1521 Practice for EvaluatingAdhesion of Installed Weath-erproofing Sealant Joints2.2 OSHA Directive:STD 1-12.026 Abrasive Operations Using Cut Off Wheelsand Masonry Saws3. Terminology3.1 DefinitionsFor definitions
9、of terms used in this guide,other than those listed below, refer to Terminology C119 andTerminology C1180.3.2 Definitions of Terms Specific to This Standard:3.2.1 defectnaturally occuring flaw in the stone.3.2.2 dimension stone restoration consultantone who isknowledgeable and experienced with the c
10、are, restoration, andrepair of building dimension stone.3.2.3 distresslocalized damage of stone units such ascracks, chips, holes, deterioration, bowing, and projections thathave been broken off or worn down caused by wear, erosion,settlement, displacement, or other adverse chemical or me-chanical a
11、ctions.3.2.4 dutchman repaira stone repair method whereby aportion of a stone unit is cut out and replaced with anotherpiece of stone (called a dutchman). The dutchman is usuallyrectangular or square in shape, but may also be rounded, and isusually at a corner or edge of the stone unit.3.2.5 pointin
12、gplacing mortar in the outer portion of thejoints between stone units. To point stone joints, the outerportion of the joints must either be left open during installationor cut or ground out, i.e. have the mortar removed from theouter portion of the joint. New mortar is then pressed into thejoint wit
13、h a pointing tool. The increased compaction of the newmortar provides an improved resistance to water penetration atthe joint compared to the primary stone setting mortar.1This guide is under the jurisdiction of ASTM Committee C18 on DimensionStone and is the direct responsibility of Subcommittee C1
14、8.07 on EnvironmentalProperties, Behavior, and Cleaning.Current edition approved Oct. 1, 2011. Published November 2011. DOI:10.1520/C1722-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volu
15、me information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.5.1 repointingthe removal of existing mortar from theouter portion of the joints between stone units
16、and thesubsequent pointing of the joints.3.2.5.2 tuck pointing (tuckpointing, tuck-pointing)thisterm is intentionally not used in this standard, because it isoften used inconsistently. It is variously used to mean repoint-ing, simply pointing, or applying a raised bead of mortar (oftenof a different
17、 color) down the middle of mortar joints.3.2.6 proprietary repair mortaran exclusively manufac-tured product formulated from cementitious compounds, fineaggregates, mineral pigments, possibly bonding agents, andother additives. It is used for filling cracks, holes, and otherdepressions in stone unit
18、s or for rebuilding the surface ofdamaged stone units to their original profile.3.2.7 repair mortar, cement-basedrepair mortar utilizingportland cement, masonry cement, blended cement, mortarcement, or natural cement as the primary binder.3.2.7.1 repair mortar, polymer-modifiedcement-based re-pair m
19、ortar incorporating a dry or liquid polymer modifier as asecondary binder, to alter the performance properties3.2.7.2 repair mortar, polymer-basedrepair mortar con-sisting of a polymer binder and aggregates, without cement orhydraulic components.4. Significance and Use4.1 The purpose of this guide i
20、s to assist those who wish torestore facades constructed of or finished with dimensionstone. It is an aid to owners, building managers, architects,engineers, contractors and others involved with restoringdimension stone.4.2 This guide is not meant to supersede manufacturersdirections and recommendat
21、ions for the use of their specificproducts, or written directions from the architect or buildingowner. When manufacturers directions are in conflict with thisguide, follow their recommendations or consult with theirtechnical staff for further direction.4.3 Prior to undertaking a full-scale repair or
22、 cleaningprocedure, the methods under consideration for repair, patch-ing or cleaning should be tested on an area not easily visible oron sample stones. The test will assist in judging the effective-ness of the chosen method and permit assessment of potentialdamage to the building stone. Completely
23、evaluate the successof the sample repairs before undertaking the full-scale cleaningor repair procedure.5. Condition Survey and Restoration Plan5.1 The first step in a restoration project is to conduct aproject survey consisting of a review of existing originalarchitectural drawings and specificatio
24、ns and any original stoneshop drawings that may be available. The stone shop drawingscontain detailed information on stone and anchoring that is notalways found in the architectural drawings. The shop drawingreview is followed by a thorough examination of all exposedstone surfaces and related elemen
25、ts of the building envelope.Document distressed areas and existing repairs. Determine thecauses of observed distress to avoid performing cosmeticrepairs while failing to correct the underlying problems. As anexample, if problems result from water damage, the source ofwater penetration must be found
26、and corrected if the repairs areto be successful and long lasting. If the damage to the stone isa result of structural instability, that structural issue must beaddressed before repairs are made.5.1.1 A dimension stone restoration consultant experiencedin natural stone facade design and construction
27、 should partici-pate in the condition survey. If structural distress is observed,consult with a qualified engineer with stone facade designexperience. For stone displaying deterioration with an un-known cause, a petrographer specializing in dimension stoneanalysis can be consulted to determine wheth
28、er a failure isrelated to inherent properties or mineralogical composition ofthe stone.5.1.2 During the condition survey, identify and documentrepairs performed during previous restorations. The conditionof existing repairs should be assessed to determine if they arestable, if they have failed, if t
29、hey are a potential threat to thebuilding fabric, or if they are posing a safety risk. Existingrepairs can be made more apparent or can be damaged bycleaning or other restoration processes. The restoration consul-tant will be able to help with the proper procedures concerningprevious repairs.5.1.3 W
30、hen necessary, appropriate field or laboratory test-ing, or both, is normally included with the condition survey toverify the nature of existing materials and the extent of thework needed to restore the project to the desired condition.Cleaning compounds and repair materials under considerationshoul
31、d be evaluated and tested to confirm that they will beeffective and will perform without detrimental effects to thestone for the life of the building.5.2 Once the condition survey is complete, prepare a resto-ration plan describing the repair and restoration work to bedone. Perform the repairs and c
32、leaning in a systematic,sequential order that will avoid damage to previously com-pleted phases of the project.5.2.1 Structural repairs must precede cosmetic repairs. Forexample, if expansion from rusting anchors is causing the stoneto crack, the anchors must be replaced or treated beforerepairing c
33、racks.5.2.2 Perform testing of existing materials sufficiently inadvance of restoration work to allow suitable cleaning, patch-ing, repair, and replacement materials to be identified.5.2.3 When chemical cleaners are used, perform the clean-ing before the patching. Some cleaning compounds adverselyaf
34、fect the color and strength of the installed patch. Performingthe cleaning first will help prevent damage or discoloration ofthe patching materials and will also allow the patch materialsto be matched to the cleaned surfaces of the original material.5.2.4 If mortar in the joints is missing or deteri
35、orated to theextent that water intrusion will occur, the joints must berepointed and allowed to cure before using a wet cleaningmethod. This is especially important if a water soak prepara-tion or pressure water spray cleaning method is specified.5.3 The National Historic Preservation Act allows qua
36、lify-ing historically significant buildings or structures to be restoredusing federal funds set aside for historic preservation. Thepermitted type and extent of restoration work may be limitedby government regulations. A formalized Historic StructuresReport is used in these cases to outline the prop
37、ertys history,C1722 112existing condition, goals for the use of the property, andprovides a recommended treatment approach and scope ofwork for restoration. The Historic Structures Report is amultidisciplinary task and a team of several consultants con-sisting of historians, architects, engineers, m
38、aterials scientists,and conservators is usually required to complete the report.6. Stone Patching6.1 Patching, GeneralPatching small areas of distress iscommonly performed in order to avoid replacing full stoneunits. This may be preferable in certain situations to preserve asmuch of the historic fab
39、ric of the structure as possible.However, areas of distress that do not impact the overallintegrity of the stone unit and will not lead to furtherdegradation of the stone, or do not detract significantly fromthe stones appearance, are often left untreated.6.1.1 Patching compounds must properly adher
40、e to andmatch the stone as closely as possible, not only in appearance,but also in physical properties. Patching materials must becompatible with original stone.6.1.2 The original stone may be repaired with a patch, inlieu of replacement, because of historic value, a lack ofavailability, or difficul
41、ty replacing whole pieces. For thesereasons, it is very important that the original stone beingrepaired be carefully protected from further damage. Thephysical properties of patching compounds should be verifiedso the resulting performance characteristics of the patch do notconflict with the perform
42、ance characteristics of the surroundingstone. It is generally agreed that it is better for the patch (whichcan be easily replaced) to fail than to cause any further damageto the existing, historically valuable, irreplaceable, facade. Inthe following paragraphs, there are specific examples ofphysical
43、 properties and how they affect the viability of thepatch with a specific stone.6.1.3 The combined compressive strength and modulus ofelasticity of the patching material should produce similar orlower performance characteristics to the analogous propertiesof the original stone for a non structural r
44、epair. Consult anexperienced stone restoration consultant to confirm that thecombined properties of the patching material do not result inperformance characteristics that could damage the particularstone for a specific project.6.1.4 Patching compounds should also have a comparablecoefficient of ther
45、mal expansion to that of the stone beingpatched. This is desirable so that the differential thermalexpansion will not stress the patch and cause a loss of bond.6.1.5 Water absorption and water vapor transmission char-acteristics of the stone must be considered when selecting apatching compound. This
46、 is especially important when patch-ing an absorptive stone. If the patch does not transmit watervapor at a similar rate as the surrounding stone, it may trapmoisture and dissolved salts behind it, which can cause thepatch to lose bond or deteriorate. This can also cause deterio-ration of the surrou
47、nding stone. Polymeric bonding agents,such as high solids epoxy, may also inhibit water vaportransmission. These are generally not recommended andshould only be used if they can demonstrate proper water vaportransmission by testing or exemplars.6.1.5.1 A patch, whether cementitious or polymer-based,
48、will normally be more obvious after wetting by rain or duringcleaning. This phenomenon occurs with most patching mate-rials and is not necessarily a sign of badly matched properties.Patching material is designed to match dry stone. Once thewetted stone returns to the dry condition, a properly instal
49、ledpatch will return to its original state, matching the surroundingstone.6.1.6 Ground stone, crushed stone, or stone dust of the samevariety as the stone being patched is sometimes added to thepatching compound to help match the patching materialproperties to the stone properties. Mixing these additionalmaterials into the patching compound can cause the patch tolose strength, lose bond, or cause difficulty in finishing.Therefore, adding material to a manufacturers patching com-pound is generally not recommended but sometimes cannot beavoided. For example, it is some
