1、Designation: C926 18bStandard Specification forApplication of Portland Cement-Based Plaster1This standard is issued under the fixed designation C926; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification covers the requirements for the appli-cation of full thickness portland cement-based plaster forexterior (stucco) and i
3、nterior work. These requirements do notby default define a unit of work or assign responsibility forcontractual purposes, which is the purview of a contract orcontracts made between contracting entities.1.2 This specification sets forth tables for proportioning ofvarious plaster mixes and plaster th
4、ickness.NOTE 1General information will be found in Annex A1. Designconsiderations will be found in Annex A2.1.3 The values stated in inch-pound units are to be regardedas the standard. The SI (metric) values given in parentheses areapproximate and are provided for information purposes only.1.4 The t
5、ext of this specification references notes andfootnotes that provide explanatory material. These notes andfootnotes (excluding those in tables and figures) shall not beconsidered as requirements of the specification.1.5 Details of construction for a specific assembly toachieve the required fire resi
6、stance shall be obtained fromreports of fire-resistance tests, engineering evaluations, orlistings from recognized fire testing laboratories.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Prin
7、ciples 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 BuildingMaterials and SystemsC25 Test Methods
8、for Chemical Analysis of Limestone,Quicklime, and Hydrated LimeC35 Specification for Inorganic Aggregates for Use in Gyp-sum PlasterC91 Specification for Masonry CementC150 Specification for Portland CementC206 Specification for Finishing Hydrated LimeC207 Specification for Hydrated Lime for Masonry
9、 Pur-posesC219 Terminology Relating to Hydraulic CementC260 Specification for Air-Entraining Admixtures for Con-creteC578 Specification for Rigid, Cellular Polystyrene ThermalInsulationC595 Specification for Blended Hydraulic CementsC631 Specification for Bonding Compounds for InteriorGypsum Plaster
10、ingC897 Specification for Aggregate for Job-Mixed PortlandCement-Based PlastersC932 Specification for Surface-Applied Bonding Com-pounds for Exterior PlasteringC1063 Specification for Installation of Lathing and Furringto Receive Interior and Exterior Portland Cement-BasedPlasterC1116 Specification
11、for Fiber-Reinforced Concrete andShotcreteC1328 Specification for Plastic (Stucco) CementC1787 Specification for Installation of Non Metallic PlasterBases (Lath) Used with Portland Cement Based Plaster inVertical Wall ApplicationsE90 Test Method for Laboratory Measurement of AirborneSound Transmissi
12、on Loss of Building Partitions andElementsE119 Test Methods for Fire Tests of Building Constructionand MaterialsE492 Test Method for Laboratory Measurement of ImpactSound Transmission Through Floor-Ceiling AssembliesUsing the Tapping Machine1This specification is under the jurisdiction of ASTM Commi
13、ttee 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 Aug. 1, 2018. Published August 2018. Originallyapproved in 1981. Last previous e
14、dition approved in 2018 as C926 18a. DOI:10.1520/C0926-18B.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 Document Summary page onthe ASTM website.*A
15、 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 international standard was developed in accordance with internationally recognized principles on standardization establ
16、ished in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.12.2 ANSI Standard:A108.1 Specification for Installation of Ceramic Tile33. Terminology3.1 Terms shall be d
17、efined as in Terminologies C11 andC219, except as modified herein.3.2 Definitions of Terms Specific to This Standard:3.2.1 accelerator, nan admixture that will shorten thesetting time of plaster.3.2.2 admixture, na material other than water, aggregate,or basic cementitious material added to the batc
18、h before orduring job mixing.3.2.3 acid etching, nthe cleansing and controlled erosionof a solid surface, using an acid wash.3.2.4 air entrainment, nthe use of an air-entraining ad-mixture or air-entraining cementitious material in a plaster mixto yield a controlled quantity of minute (typically bet
19、ween 10and 1000 m in diameter) disconnected air bubbles in theplaster (see entrapped air).3.2.5 back wrap, na means of terminating a polymer-modified, fabric reinforced cementitious base coat by wrappingthe reinforcing mesh, which has been affixed to the substrateonto the outboard surface of the foa
20、m plastic core to providecontinuity of the reinforced base coat and protection for thefoam plastic core.3.2.6 backplaster, nplaster applied to the face of metallath opposite a previously applied plaster.3.2.7 barrier wall, ntype of wall system that is intended toblock or interrupt the movement of wa
21、ter to the interior.3.2.8 bond, nthe state of adhesion between plaster coats orbetween plaster and plaster base.3.2.9 bonding compound or agent, ncompounds surfaceapplied or integrally mixed with plaster to improve the qualityof bond between plaster and plaster base or between plastercoats.3.2.10 ce
22、mentitious material, na material that, whenmixed with water and with or without aggregate, provides theplasticity and the cohesive and adhesive properties necessaryfor placement and the formation of a rigid mass.3.2.11 coat, na thickness of plaster applied in a singleoperation.3.2.11.1 basecoat, nal
23、l plaster applied before the applica-tion of the finish coat.3.2.11.2 bedding coat, na plaster coat that receives aggre-gate or other decorative material impinged into its surfacebefore it sets.3.2.11.3 brown coat, nin three-coat work, the second coat,applied over the scratch coat. In two-coat work,
24、 brown coatrefers to the double-up basecoat. In either use, the brown coatis the coat directly beneath the finish coat.3.2.11.4 dash-bond coat, na thick wet mixture of portlandcement and water, with or without aggregate, dashed onto thesurface of a plaster base such as smooth monolithic concrete orc
25、oncrete block surfaces to improve the mechanical key forsubsequent plaster coats.3.2.11.5 double-up coat, nthe brown-coat plaster appliedto the scratch coat plaster before the scratch-coat plaster hasset.3.2.11.6 finish coat, nthe final layer of plaster applied overbasecoat plaster.3.2.11.7 fog coat
26、, na light coat of cement and water, withor without aggregate or color pigment, applied by machinespray to improve color consistency.3.2.11.8 scratch coat, nthe first coat of plaster applied toa plaster base.3.2.11.9 skim coat, na thin finish coat applied to anexisting plaster surface or other subst
27、rate to improve appear-ance.3.2.11.10 three-coat work, napplication of plaster in threesuccessive coats with time between coats for setting or drying,or both.3.2.12 cold joint (“joining” or “jointing”), nthe junctureof fresh plaster application adjacent to set plaster, in the sameplane.3.2.13 curing
28、, vthe act or processes of producing a mois-ture environment favorable to cement hydration, resulting inthe setting or hardening of the plaster.3.2.14 drainage wall, na wall system in which the clad-ding provides a substantial barrier to water intrusion, andwhich also incorporates a concealed water-
29、resistive barrierover which drainage will occur.3.2.15 entrapped air, nunintentional air voids in the plas-ter generally larger than 1 mm.3.2.16 factory prepared (“mill-mixed” or “ready mixed”),adjpertaining to material combinations that have been for-mulated and dry-blended by the manufacturer, req
30、uiring onlythe addition of and mixing with water to produce plaster.3.2.17 fiber, natural or synthetic, nan elongated fiber orstrand admixture added to plaster mix to improve cohesivenessor pumpability, or both.3.2.18 floating, vact of compacting and leveling brown-coat plaster to a reasonably true
31、surface plane using a float toolor the act of bringing the aggregate to the surface of finish-coatplaster.3.2.19 key (also mechanical key), nplaster that physicallysurrounds, penetrates, or deforms to lock onto the perforationsor irregularities of the plaster base or previous coat of plaster.3.2.20
32、metal plaster base, nexpanded metal lath, orwelded or woven wire lath.3.2.21 plaster, nportland cement-based cementitious mix-ture (see stucco).3.2.22 polymer modified cementitious base coat, nA basecoat containing portland cement modified with chemical ad-mixtures (typically polymer latexes) to imp
33、rove characteristicsof the finished product, such as workability, plasticity, waterresistance, and adhesion.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.C926 18b23.2.23 required, adjpertaining to a mandatory obligationimposed by a force o
34、utside of this specification, such as abuilding code, project specification, contract, or purchaseorder.3.2.24 rustication (also “break”), nan interruption orchange in plane of a plastered surface.3.2.25 scoring (also known as “scratching”), nthe groov-ing of the surface of an unset plaster coat to
35、provide a key fora subsequent coat.3.2.26 set, nthe chemical and physical change in plaster asit goes from a plastic, workable state to a rigid state.3.2.27 solid plaster bases, nsubstrates that do not requirea metal plaster base, including cast in place and precastconcrete, concrete and stone mason
36、ry, clay brick, and tile.3.2.28 stucco, nportland cement-based plaster used onexterior locations.3.2.29 stucco finish, na factory-prepared, dry blend ofmaterials for finish coat applications.3.2.30 temper, vto mix or restore unset plaster with waterto a workable consistency.3.2.31 texture, nany surf
37、ace appearance as contrasted to asmooth surface.3.3 Definitions of Terms Not Specific to This Standard3.3.1 contract documents, na series of several individualitems that generally include drawings and specifications. Eitheror both of these documents may exist for any particular project.4. Delivery a
38、nd Storage of Materials4.1 Delivery:4.1.1 Packaged materials shall be delivered in factory-sealed, unopened, and unbroken packages, containers, orbundles.4.1.2 Bulk materials shall be delivered in clean transportvessels, free of contaminates.4.2 Storage:4.2.1 Weather-sensitive materials shall be kep
39、t in a drycondition until ready for use. (See A2.4.)4.2.2 Bulk materials shall be stored to prevent subsequentcontamination and segregation.5. Materials5.1 Materials shall conform to the requirements of thereferenced specifications and standards and to the requirementsspecified herein.5.2 Cement:5.2
40、.1 Portland CementSpecification C150, Type I, II, andIII, as specified. White where specified.5.2.2 Air-Entraining Portland CementSpecification C150,type as specified. White where specified.5.2.3 Masonry CementSpecification C91, Types N, S, andM. White where specified.5.2.4 Blended Hydraulic CementS
41、pecification C595,Type IP, IS(70), IL, and IT(S70), as specified.5.2.5 Air-Entraining Blended Hydraulic CementSpecification C595, Type IP-(A), IS(70)-(A), IL-(A), and IT(S70)-(A), as specified.5.2.6 Plastic CementPlastic Cement shall meet the re-quirements of Specification C1328, Standard Specificat
42、ion forPlastic (Stucco) Cement.NOTE 2Plastic cements are not available nationally.5.3 Type “S” Hydrated LimeAhydrated lime that containsnot more than 8 % unhydrated oxides when tested in accor-dance with Test Methods C25. See Specifications C206 andC207 for a complete description of a Type “S” hydra
43、ted lime.5.4 Aggregates:5.4.1 Sand for Base CoatsSpecification C897. Aggregatefailing to meet gradation limits in Specification C897 shall bepermitted to be used, provided the plaster made with this sandhas an acceptable demonstrated performance record in similarconstruction and climate conditions.5
44、.4.2 PerliteSpecification C35.5.4.3 Sand for Job-Mixed Finish CoatsSpecificationC897.5.5 WaterWater used in mixing, application, and finishingof plaster shall be clean, fresh, suitable for domestic waterconsumption, and free of such amounts of mineral or organicsubstances as would affect the set, th
45、e plaster, or any metal inthe system.5.6 AdmixturesSee 3.2.2 and A2.5.5.7 FibersSpecification C1116 on alkali-resistant fibers,glass fibers, nylon, polypropylene or carbon fibers.5.8 Product MarkingPackaged materials shall be clearlymarked or labeled to indicate product, brand name, themanufacturer,
46、 and the weight of the material contained therein.Similar information shall be provided in the shipping advicesaccompanying the shipment of bulk materials.6. Requirements for Bases to Receive Portland Cement-Based Plaster6.1 Metal plaster bases, lathing accessories, furring acces-sories and fastener
47、s used to receive plaster shall be installed inconformance with Specification C1063, except as otherwisespecified. Non-metallic plaster bases used to receive plastershall be installed in conformance with Specification C1787.NOTE 3Plaster bases and lathing accessories shall be free of delete-rious am
48、ounts of rust, oil, or other foreign matter, which could cause bondfailure or unsightly discoloration.6.2 Surfaces of solid bases to receive plaster, such asmasonry, stone, cast-in-place or precast concrete shall bestraight and true within14 in. (6 mm) in 10 ft (3 m) and shallbe free of form oil or
49、other elements, which would interferewith bonding. Conditions where the surfaces are out oftolerance shall be corrected prior to the application of theplaster. Ferrous-containing form ties or other obstructions shallbe removed or receded a minimum18 in. (3 mm) below thesurface of the solid base and treated with a corrosion-resistantcoating. Non-ferrous protuberances shall be permitted to betrimmed back even with the surface of the solid base.C926 18b36.2.1 Solid surfaces shall have the suction (ability to absorbwater) o
