1、Designation: C843 17Standard Specification forApplication of Gypsum Veneer Plaster1This standard is issued under the fixed designation C843; 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 par
2、entheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope*1.1 This specification covers the minimum requirements forand met
3、hods of applying gypsum veneer plaster.1.2 Where a specific degree of fire resistance is required forveneer plaster systems, applicable building code regulationsshall be followed.1.2.1 Details of construction for a specific assembly toachieve the required fire resistance shall be obtained fromreport
4、s of fire-resistance tests, engineering evaluations, orlistings from recognized fire testing laboratories.1.3 Where a specific degree of sound control is required forveneer plaster assemblies and constructions, details of con-struction shall be in compliance with official reports of testsconducted i
5、n recognized sound testing laboratories in accor-dance with the applicable sound tests of Test Methods E90,C423,orE492.NOTE 1To ensure desirable results, coordinate this specification withSpecification C844.NOTE 2General information regarding matters of a contractual natureconcerning veneer plaster
6、work is found in Appendix X1. Additionaltechnical information related to veneer plastering is provided in AppendixX2.1.4 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.5 The text of this specification references note
7、s andfootnotes which provide explanatory material. These notes andfootnotes (excluding those in tables and figures) shall not beconsidered as requirements of the specification.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization
8、established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2C11 Terminology Relating to Gypsum and Related BuildingMat
9、erials and SystemsC423 Test Method for SoundAbsorption and SoundAbsorp-tion Coefficients by the Reverberation Room MethodC587 Specification for Gypsum Veneer PlasterC588/C588M Specification for Gypsum Base for VeneerPlasters (Withdrawn 2005)3C631 Specification for Bonding Compounds for InteriorGypsu
10、m PlasteringC844 Specification for Application of Gypsum Base toReceive Gypsum Veneer PlasterC1047 Specification for Accessories for Gypsum Wallboardand Gypsum Veneer BaseE90 Test Method for Laboratory Measurement of AirborneSound Transmission Loss of Building Partitions andElementsE492 Test Method
11、for Laboratory Measurement of ImpactSound Transmission Through Floor-Ceiling AssembliesUsing the Tapping Machine3. Terminology3.1 Definitions:3.1.1 See Terminology C11.3.2 Definitions of Terms Specific to This Standard:3.2.1 base coat, nveneer plaster trowel or machine ap-plied as the first coat of
12、a two-component system.3.2.2 finish coat, nveneer finish plaster trowel or machineapplied as the second coat over the base coat plaster in atwo-component system.3.2.2.1 smooth-trowel finish, na finish resulting from steeltroweling with a minimum of water after the plaster has1This specification is u
13、nder the jurisdiction of ASTM Committee C11 onGypsum and Related Building Materials and Systems and is the direct responsibilityof Subcommittee C11.03 on Specifications for theApplication of Gypsum and OtherProducts in Assemblies.Current edition approved May 1, 2017. Published May 2017. Originallyap
14、proved in 1976. Last previous edition approved in 2012 as C843 99 (2012).DOI: 10.1520/C0843-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Documen
15、t Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis
16、 international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TB
17、T) Committee.1become firm. A smooth finish free of trowel marks, blemishes,or other imperfections.3.2.2.2 texture finish, na finish resulting from (1) trowelapplication followed by floating or texturing of the surface withany of a variety of tools using a minimum of water or (2)machine application,
18、left as applied or followed by handtexturing.3.2.3 joint-reinforcing embedment, nthe cementitious ma-terial used to embed the strip material that is compatible withthe veneer plaster used.3.2.4 one-component system, na veneer plaster systemdesigned for application directly over approved bases in asi
19、ngle plaster mix applied in a single coat or double-backoperation with the same material.3.2.5 reinforced joint, na joint between gypsum base thatis reinforced with strip material embedded in a cementitiousmaterial.3.2.6 reinforcing, njoint reinforcing tape or mesh (stripmaterial) that is applied ov
20、er flat joints and interior angles.3.2.7 two-component system, na veneer plaster systeminvolving two separate materials mixed and applied separatelyfor base coat and finish coat.3.2.8 veneer plaster system, ngypsum veneer plaster ap-plied to (1) a gypsum base in accordance with 10.1 or (2)properly p
21、repared masonry or monolithic concrete surfaces,neither side of which is exposed to moisture. The plaster shallbe applied with one or more components not exceeding14 in.(6.4 mm) in total thickness.4. Delivery of Materials4.1 All manufactured materials shall be delivered in theoriginal packages, cont
22、ainers, or cartons bearing the brandname and manufacturer identification.5. Protection of Materials5.1 Plasters and other cementitious materials shall be keptdry until ready to be used; they shall be kept off the ground,under cover, and away from damp walls and surfaces.6. Environmental Conditions6.
23、1 TemperatureWhen the ambient outside temperature atthe building site is less than 55F (13C), maintain a tempera-ture in the building of not less than 55F (13C) or not morethan 80F (27C) for not less than 24 h prior to the applicationof veneer plaster and for one week after the veneer plaster hasset
24、 or until the veneer plaster has dried. Distribute heat evenlyin all work areas, and use deflection or protective screens toprevent concentrated or uneven heat or cold on the veneerplaster.NOTE 3The requirements in 6.1 will minimize the cracking of veneerplaster due to structural movements caused by
25、 thermal changes fromtemperature extremes; and dry-outs due to hot spots caused by concen-trated heat.6.2 VentilationVentilation shall be provided to removeexcess water given off through the drying process.7. Materials7.1 Gypsum Base for Veneer Plasters (hereinafter referredto as “gypsum base”) Spec
26、ification C588/C588M.7.2 Veneer PlastersSpecification C587.7.3 ReinforcingNoncorrosive strip providing the jointstrength requirements of Specification C587.7.4 Liquid Bonding CompoundsSpecification C631 (seeX2.3).7.5 WaterWater shall be clean, fresh, and of potable waterquality.7.6 AccessoriesSpecif
27、ication C1047.8. Surface Preparation8.1 ExaminationCarefully examine all surfaces, includingbut not limited to, unit masonry, monolithic concrete, gypsumbases of all types, and accessories to receive veneer plaster,before the veneer plaster is applied. Notify the proper authori-ties promptly of all
28、unsatisfactory conditions. The examinationshall determine whether the gypsum base has been exposed toexcessive sunlight. Do not apply veneer plaster until after suchunsatisfactory conditions are rectified to the satisfaction of theplastering contractor.NOTE 4The bond of alkaline veneer plaster to gy
29、psum base may beimpaired if the base is exposed to direct light or sunlight for extendedperiods.8.1.1 Do not apply veneer plaster over any surfaces of unitmasonry or concrete that have been coated with any bitumi-nous compound or other waterproofing or damproofing or formrelease agent.8.2 Conditioni
30、ng of Surfaces:8.2.1 Immediately before the plaster is applied, wet downthe masonry surfaces on which suction shall be reduced.Visible water shall not remain on the surface.8.2.2 Carefully examine accessories, such as corner beads,control joints, casing beads, and so forth, to ensure that they arest
31、raight, curved, plumb, level, square, or true to the requiredangles and have been applied in a manner to ensure fullcoverage of flanges before the plaster is applied.8.3 Monolithic Concrete SurfacesClean monolithic con-crete surfaces of all dust, loose particles, and other foreignmatter. Completely
32、remove all grease, oil, noncompatiblecuring compounds, and form releasing agents. Remove allridges and protrusions greater that18 in. (3.2 mm) and fill alldepressions greater than14 in. (6.4 mm) level with portlandcement mortar and allow to set and dry. Any further prepara-tion shall be as recommend
33、ed by the veneer plaster manufac-turer.8.4 Gypsum Base Joint ReinforcementReinforce all inte-rior angles and flat joints prior to application of the veneerplaster over the base.8.4.1 Interior AnglesPosition and secure reinforcementwith staples (on 12-in. (305-mm) centers, one side only),veneer plast
34、er, or other cementitious material compatible withthe veneer plaster or by using self-adhering strip reinforce-ment. When stapling, staple along the ceiling edge only forC843 172wall-to-ceiling angles and along one edge for wall-to-wallangles. When securing reinforcement with veneer plaster,reinforc
35、ement shall be thoroughly embedded so that embed-ment material is both under and covering reinforcement.8.4.2 Flat JointsCenter reinforcement over the joint lineof the gypsum base and secure with staples or veneer plaster ifnot using self-adhering reinforcement. Keep reinforcementtight and flat agai
36、nst the gypsum base, and when stapling,position the staples no farther than 24 in. (610 mm) apart,staggered along each edge. Embed reinforcement and continueapplication of the veneer plaster over the field of the base.(WarningThis method provides minimum reinforcement ofthe joints. To minimize incid
37、ence and severity of joint ridgingand cracking, use one of the following methods (8.4.2.1,8.4.2.2,or8.4.2.3) in the absence of any specific methodrecommended by the veneer plaster manufacturer. Where papertape and setting-type joint compounds are used, use 8.4.2.3.)8.4.2.1 Reinforcement over Set Ven
38、eer PlasterTightlytrowel veneer plaster over the joint line leaving the plasterfeathered out to a width of about 6 in. (152 mm) flush with theface of the gypsum base. Allow the plaster to set; then securereinforcement over the joint line as described in 8.4.2.8.4.2.2 Reinforcement Secured and Embedd
39、ed with VeneerPlasterApply reinforcement over the joint line as describedin 8.4.2. Tightly trowel the plaster over the reinforcement alongthe joint line to provide thorough embedment of the reinforce-ment.Allow the joint embedment to set before proceeding withgeneral plastering.8.4.2.3 Reinforcement
40、 Embedded (no staples)Tightlytrowel the embedment material to a depth of about132 in.(0.8 mm), working the trowel in both directions along the jointline. Center the reinforcement over the joint line. Firmly andevenly press the reinforcement into the soft embedment mate-rial using a little soft mater
41、ial on the trowel to bury itcompletely, and leave the embedment material feathered out toa width of about 6 in. (152 mm) flush with the face of thegypsum base. Allow the embedment material to set beforeproceeding with general plastering.9. Mixing9.1 Do not use frozen, caked, or lumpy material. Do no
42、tretemper or use material that has partially set. Mix each batchseparately. Clean mixers thoroughly after each batch so as notto accelerate the following batches. This can be done by sprayhosing the mixer paddle and containers immediately after eachbatch. Water ratios and other techniques used for m
43、ixing shallconform to the manufacturers recommendation for specificveneer plaster products. In the absence of explicit directions,follow the recommendations in X2.1.9.2 Setting TimeSetting times are carefully controlled bythe manufacturer. Do not make adjustments to the setting timeon the job. If pr
44、oblems with setting develop under unusual jobconditions, consult the manufacturer of the veneer plaster forrecommendations.9.2.1 Do not use gauging, molding, or casting plasters, lime,gypsum, Keenes cement, portland cement, and so forth toadjust the veneer plaster setting time.9.3 Occasionally, spec
45、ial textures are desired that requireadditional sand. Approval of the veneer plaster manufacturershall be obtained prior to any such additions.10. Application10.1 GeneralVeneer plasters have widely differing work-ing properties, physical characteristics, and limitations regard-ing their compatibilit
46、y with one another and with variousbases. Follow the particular methods, techniques, limitations,and procedures set forth by individual manufacturers for theirproduct. In the absence of manufacturers directions, follow therecommendations in X2.2.10.2 Plaster ThicknessMeasure the plaster thickness fr
47、omthe face of the base to which it is applied, exclusive of jointtreatment. The minimum thickness shall be as recommendedby the manufacturer of the plaster used but in no case less thanshown as follows:Base coats (trowel applied)116 in. (1.6 mm) minBase coats (spray applied)116 in. (1.6 mm) minFinis
48、hes (two-component systems)132 in. (0.8 mm) to116 in. (1.6 mm) minOne-component systems116 in. (1.6 mm) min10.3 Barriers shall be provided to prevent the free circula-tion of hot, dry winds over the face of freshly applied plaster.11. Electric Radiant Heat Cable11.1 Veneer plaster shall be applied t
49、o electric heat cablesystems in accordance with the veneer plaster manufacturersdirections. In the absence of manufacturers directions followthe recommendations in X2.5.11.2 Veneer plaster shall not be applied over heating sys-tems in which the wire temperature will, at any time, be inexcess of 125F (52C).12. Keywords12.1 electric heat cable; gypsum; plaster; veneer plasterC843 173APPENDIXES(Nonmandatory Information)X1. GENERAL INFORMATIONX1.1 Construct and maintain scaffolding in strict confor-mity with applicable laws and or
