1、Designation: C843 99 (Reapproved 2012)Standard 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 revisio
2、n. A number in parentheses 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 Department of Defense.1. Scope1.1 This specification covers the minimum requirement
3、s forand methods 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 obtaine
4、d fromreports 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 test
5、sconducted in 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 ven
6、eer plaster 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 ref
7、erences notes andfootnotes which provide explanatory material. These notes andfootnotes (excluding those in tables and figures) shall not beconsidered as requirements of the specification.2. Referenced Documents2.1 ASTM Standards:2C11 Terminology Relating to Gypsum and Related BuildingMaterials and
8、SystemsC423 Test Method for Sound Absorption and Sound Ab-sorption Coefficients by the Reverberation Room MethodC587 Specification for Gypsum Veneer PlasterC588/C588M Specification for Gypsum Base for VeneerPlasters3C631 Specification for Bonding Compounds for InteriorGypsum PlasteringC844 Specifica
9、tion 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 and Ele-mentsE492 Test Method for Laboratory Measureme
10、nt 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 a two-component system.3
11、.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 hasbecome firm. A smooth finish free of trowel mark
12、s, 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, left as applied or followed by handtexturing.1This specificati
13、on is under 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 March 1, 2012. Published June 2012. Or
14、iginallyapproved in 1976. Last previous edition approved in 2006 as C84399 (2006). DOI:10.1520/C0843-99R12.2For 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 stand
15、ards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.3 joint-reinforcing embedment, nthe ceme
16、ntitious 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 asingle plaster mix applied in a single coat or double-backoperation with the same material.
17、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 over flat joints and interior angles.3.2.7 two-component system, na veneer plaster systemin
18、volving 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 prepared masonry or monolithic concrete surfaces,neither side of which is exposed to moist
19、ure. 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, containers, or cartons bearing the brandname and manufacturer identification.5. Protection of
20、 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 Conditions6.1 TemperatureWhen the ambient outside temperature atthe building site is less than 55 F (
21、13 C), maintain atemperature in the building of not less than 55 F (13 C) or notmore than 80 F (27 C) for not less than 24 h prior to theapplication of veneer plaster and for one week after the veneerplaster has set or until the veneer plaster has dried. Distributeheat evenly in all work areas, and
22、use deflection or protectivescreens to prevent concentrated or uneven heat or cold on theveneer plaster.NOTE 3The requirements in 6.1 will minimize the cracking of veneerplaster due to structural movements caused by thermal changes fromtemperature extremes; and dry-outs due to hot spots caused by co
23、ncen-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”) Specification C588/C588M.7.2 Veneer PlastersSpecification C587.7.3 ReinforcingNoncorrosiv
24、e 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 AccessoriesSpecification C1047.8. Surface Preparation8.1 ExaminationCarefully examine all surfaces, in
25、cludingbut 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 unsatisfactory conditions. The examinationshall determine whether the gypsum base has
26、 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 gypsum base may beimpaired if the base is exposed to direct light or sunlight for exten
27、dedperiods.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 Conditioning of Surfaces:8.2.1 Immediately before the plaster is applied, wet downthe masonry s
28、urfaces 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, etc., to ensure that they arestraight, curved, plumb, level, square, or true to the requiredangles and have been applied in
29、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 remove all grease, oil, noncompatiblecuring compounds, and form releasing agents. Remove allr
30、idges 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 recommended by the veneer plaster manufac-turer.8.4 Gypsum Base Joint ReinforcementReinforce all inte-
31、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 plaster, or other cementitious material compatible withthe veneer plaster or by using self-adherin
32、g strip reinforce-ment. When stapling, staple along the ceiling edge only forwall-to-ceiling angles and along one edge for wall-to-wallangles. When securing reinforcement with veneer plaster,reinforcement shall be thoroughly embedded so that embed-ment material is both under and covering reinforceme
33、nt.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 against the gypsum base, and when stapling,position the staples no farther than 24 in. (610 mm) apart,sta
34、ggered 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 incidence and severity of joint ridgingC843 99 (2012)2and cracking, use one of the following methods (8.4.
35、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 Veneer PlasterTightlytrowel veneer plaster over the joint line leaving the plasterfeather
36、ed 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 Embedded with VeneerPlasterApply reinforcement over the joint line as describedin 8.4.2. Tig
37、htly 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 Embedded (no staples)Tightlytrowel the embedment material to a depth of about132 in.
38、(0.8mm), working the trowel in both directions along the joint line.Center the reinforcement over the joint line. Firmly and evenlypress the reinforcement into the soft embedment material usinga little soft material on the trowel to bury it completely, andleave the embedment material feathered out t
39、o a width of about6 in. (152 mm) flush with the face of the gypsum base. Allowthe embedment material to set before proceeding with generalplastering.9. Mixing9.1 Do not use frozen, caked, or lumpy material. Do notretemper or use material that has partially set. Mix each batchseparately. Clean mixers
40、 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 mixing shallconform to the manufacturers recommendation for specificveneer plaster produc
41、ts. 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 problems with setting develop under unusual jobconditions, consult the manufacturer of the
42、 veneer plaster forrecommendations.9.2.1 Do not use gauging, molding, or casting plasters, lime,gypsum, Keenes cement, portland cement, etc. to adjust theveneer plaster setting time.9.3 Occasionally, special textures are desired that requireadditional sand. Approval of the veneer plaster manufacture
43、rshall 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 compatibility with one another and with variousbases. Follow the particular methods, techniques, limitations
44、,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 fromthe face of the base to which it is applied, exclusive of jointtreatment. The minimum thicknes
45、s 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) minFinishes (two-componentsystems)132 in. (0.8 mm) to116 in. (1.6mm) minOne-component systems116 in. (1.
46、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 to electric heat cablesystems in accordance with the veneer plaster manufacturersdirections. In the
47、 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 125 F (52 C).12. Keywords12.1 electric heat cable; gypsum; plaster; veneer plasterAPPENDIXES(Nonmandat
48、ory Information)X1. GENERAL INFORMATIONX1.1 Construct and maintain scaffolding in strict confor-mity with applicable laws and ordinances so as not to interferewith or obstruct the work of others.X1.2 Coordinate the work with the work of other trades.C843 99 (2012)3X2. TECHNICAL INFORMATIONX2.1 Mixin
49、g:X2.1.1 EquipmentA paddle-type agitator fitted to a12-hp(373-W) heavy-duty, electric drill, rated from 900 to 1000 rpm(no load), and a clean drum of convenient size are recom-mended for rapid, efficient mixing of veneer plasters.X2.1.2 Procedure:X2.1.2.1 Put all but 1 or 2 qt (0.94 or 1.89 L) of the properamount of water in the mixer for each bag of veneer plaster tobe mixed.X2.1.2.2 Add the veneer plaster to the water and immedi-ately mix until uniformly wetted. Veneer plaster may be addedwhile the agitator is turning.X2.1.
