1、Designation: C926 12Standard 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 numbe
2、r 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 in
3、terior work.1.2 This specification sets forth tables for proportioning ofvarious plaster mixes and plaster thickness.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
4、 (metric) values given in parentheses areapproximate and are provided for information purposes only.1.4 The text of this specification references notes andfootnotes that provide explanatory material. These notes andfootnotes (excluding those in tables and figures) shall not beconsidered as requireme
5、nts of the specification.1.5 Details of construction for a specific assembly toachieve the required fire resistance shall be obtained fromreports of fire-resistance tests, engineering evaluations, orlistings from recognized fire testing laboratories.2. Referenced Documents2.1 ASTM Standards:2C11 Ter
6、minology Relating to Gypsum and Related BuildingMaterials and SystemsC25 Test Methods for Chemical Analysis of Limestone,Quicklime, and Hydrated LimeC35 Specification for Inorganic Aggregates for Use inGypsum PlasterC91 Specification for Masonry CementC150 Specification for Portland CementC206 Speci
7、fication for Finishing Hydrated LimeC207 Specification for Hydrated Lime for Masonry Pur-posesC219 Terminology Relating to Hydraulic CementC260 Specification for Air-Entraining Admixtures for Con-creteC595 Specification for Blended Hydraulic CementsC631 Specification for Bonding Compounds for Interi
8、orGypsum PlasteringC897 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-BasedPlasterC111
9、6 Specification for Fiber-Reinforced Concrete andShotcreteC1328 Specification for Plastic (Stucco) CementE90 Test Method for Laboratory Measurement of AirborneSound Transmission Loss of Building Partitions and Ele-mentsE119 Test Methods for Fire Tests of Building Constructionand MaterialsE492 Test M
10、ethod for Laboratory Measurement of ImpactSound Transmission Through Floor-Ceiling AssembliesUsing the Tapping Machine2.2 ANSI Standard:A108.1 Specification for Installation of Ceramic Tile33. Terminology3.1 Terms shall be defined as in Terminologies C11 andC219, except as modified herein.3.2 Defini
11、tions of Terms Specific to This Standard:3.2.1 acceleratoran admixture that will shorten the set-ting time of plaster.3.2.2 admixturea material other than water, aggregate, orbasic cementitious material added to the batch before or duringjob mixing.1This specification is under the jurisdiction of AS
12、TM 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 April 15, 2012. Published August 2012. Originallyapproved in 1981. Last
13、previous edition approved in 2011 as C92611a. DOI:10.1520/C0926-12.2For 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 we
14、bsite.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.2.3
15、acid etchingthe cleansing and controlled erosion ofa solid surface, using an acid wash.3.2.4 air entrainmentthe use of an air-entraining admix-ture or air-entraining cementitious material in a plaster mix toyield a controlled quantity of minute (typically between 10 and1000 m in diameter) disconnect
16、ed air bubbles in the plaster(see entrapped air).3.2.5 backplasterplaster applied to the face of metal lathopposite a previously applied plaster.3.2.6 barrier walltype of wall system that is intended toblock or interrupt the movement of water to the interior.3.2.7 bondthe state of adhesion between p
17、laster coats orbetween plaster and plaster base.3.2.8 bonding compound or agentcompounds surface ap-plied or integrally mixed with plaster to improve the quality ofbond between plaster and plaster base or between plaster coats.3.2.9 cementitious materiala material that, when mixedwith water and with
18、 or without aggregate, provides theplasticity and the cohesive and adhesive properties necessaryfor placement and the formation of a rigid mass.3.2.10 coata thickness of plaster applied in a singleoperation.3.2.10.1 basecoatall plaster applied before the applicationof the finish coat.3.2.10.2 beddin
19、g coata plaster coat that receives aggre-gate or other decorative material impinged into its surfacebefore it sets.3.2.10.3 brown coatin three-coat work, the second coat,applied over the scratch coat. In two-coat work, brown coatrefers to the double-up basecoat. In either use, the brown coatis the c
20、oat directly beneath the finish coat.3.2.10.4 dash-bond coata thick wet mixture of portlandcement and water, with or without aggregate, dashed onto thesurface of a plaster base such as smooth monolithic concrete orconcrete block surfaces to improve the mechanical key forsubsequent plaster coats.3.2.
21、10.5 double-up coatthe brown-coat plaster applied tothe scratch coat plaster before the scratch-coat plaster has set.3.2.10.6 finish coatthe final layer of plaster applied overbasecoat plaster.3.2.10.7 fog coata light coat of cement and water, with orwithout aggregate or color pigment, applied by ma
22、chine sprayto improve color consistency.3.2.10.8 scratch coatthe first coat of plaster applied to aplaster base.3.2.10.9 skim coata thin finish coat applied to an existingplaster surface or other substrate to improve appearance.3.2.10.10 three-coat workapplication of plaster in threesuccessive coats
23、 with time between coats for setting or drying,or both.3.2.11 cold joint (“joining” or “jointing”)the juncture offresh plaster application adjacent to set plaster, in the sameplane.3.2.12 curingthe act or processes of producing a moistureenvironment favorable to cement hydration, resulting in theset
24、ting or hardening of the plaster.3.2.13 drainage walla wall system in which the claddingprovides a substantial barrier to water intrusion, and which alsoincorporates a concealed water-resistive barrier over whichdrainage will occur.3.2.14 entrapped airunintentional air voids in the plastergenerally
25、larger than 1 mm.3.2.15 factory prepared (“mill-mixed” or “ready mixed”)pertaining to material combinations that have been formulatedand dry-blended by the manufacturer, requiring only theaddition of and mixing with water to produce plaster.3.2.16 fiber, natural or synthetican elongated fiber orstra
26、nd admixture added to plaster mix to improve cohesivenessor pumpability, or both.3.2.17 floatingact of compacting and leveling brown-coatplaster to a reasonably true surface plane using a float tool orthe act of bringing the aggregate to the surface of finish-coatplaster.3.2.18 key (also mechanical
27、key)plaster that physicallysurrounds, penetrates, or deforms to lock onto the perforationsor irregularities of the plaster base or previous coat of plaster.3.2.19 metal plaster baseexpanded metal lath, or weldedor woven wire lath.3.2.20 plasterportland cement-based cementitious mix-ture (see stucco)
28、.3.2.21 requiredpertaining to a mandatory obligation im-posed by a force outside of this specification, such as a buildingcode, project specification, contract, or purchase order.3.2.22 rustication (also “break”)an interruption orchange in plane of a plastered surface.3.2.23 scoring (also known as “
29、scratching”)the groovingof the surface of an unset plaster coat to provide a key for asubsequent coat.3.2.24 setthe chemical and physical change in plaster as itgoes from a plastic, workable state to a rigid state.3.2.25 solid plaster bases, nsubstrates that do not requirea metal plaster base, inclu
30、ding cast in place and precastconcrete, concrete and stone masonry, clay brick, and tile.3.2.26 stuccoportland cement-based plaster used on exte-rior locations.3.2.27 stucco finisha factory-prepared, dry blend of ma-terials for finish coat applications.3.2.28 temper, vto mix or restore unset plaster
31、 with waterto a workable consistency.3.2.29 textureany surface appearance as contrasted to asmooth surface.4. Materials4.1 Materials shall conform to the requirements of thereferenced specifications and standards and to the requirementsspecified herein.4.2 Cement:4.2.1 Portland CementSpecification C
32、150, Type I, II, andIII, as specified. White where specified.4.2.2 Air-Entraining Portland CementSpecificationC150, type as specified. White where specified.4.2.3 Masonry CementSpecification C91, Types N, S, andM. White where specified.4.2.4 Blended Hydraulic CementSpecification C595,Type IP, I(PM),
33、 IS, and I(SM) as specified.C926 1224.2.5 Air-Entraining Blended Hydraulic CementSpecification C595, Type IP-A, I(PM)-A, IS-A, and I(SM)-Aas specified.4.2.6 Plastic CementPlastic Cement shall meet the re-quirements of Specification C1328, Standard Specification forPlastic (Stucco) Cement.NOTE 2Plast
34、ic cements are not available nationally.4.3 Type “S” Hydrated LimeA hydrated lime that con-tains not more than 8 % unhydrated oxides when tested inaccordance with Test Methods C25. See Specifications C206and C207 for a complete description of a Type “S” hydratedlime.4.4 Aggregates:4.4.1 Sand for Bas
35、e 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.4.4.2 PerliteSpecification C35.4.4.3 Sand f
36、or Job-Mixed Finish CoatsSpecificationC897.4.5 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, the plaster, or any metal inthe system.4.6 A
37、dmixturesSee 3.2.2 and A2.5.4.7 FibersSpecification C1116 on alkali-resistant fibers,glass fibers, nylon, polypropylene or carbon fibers.5. Requirements for Bases to Receive Portland Cement-Based Plaster5.1 Metal bases and accessories used to receive plaster shallbe installed in conformance with Spe
38、cification C1063, exceptas otherwise specified.NOTE 3All metal, or PVC, or CPVC plastic members should be freeof deleterious amounts of rust, oil, or other foreign matter, which couldcause bond failure or unsightly discoloration.5.2 Surfaces of solid bases to receive plaster, such asmasonry, stone,
39、cast-in-place or precast concrete shall bestraight and true within14 in. in 10 ft (2.1 mm/m) and shall befree of form oil or other elements, which would interfere withbonding. Conditions where the surfaces are out of toleranceshall be corrected prior to the application of the plaster. Formties or ot
40、her obstructions shall be removed or trimmed backeven with the surface of the solid base.5.2.1 Solid surfaces shall have the suction (ability to absorbwater) or surface roughness, or both, to provide the bondrequired for the plaster.5.2.2 Smooth or nonabsorbent solid surfaces, such as cast-in-place
41、or precast concrete, shall be prepared to receiveportland cement plaster by one of the following methods:5.2.2.1 Sandblasting, wire brushing, acid etching, or chip-ping or a combination thereof,5.2.2.2 Application of a dash-bond coat applied forcefullyagainst the surface, left untroweled, undisturbe
42、d, and moistcured for at least 24 h, or5.2.2.3 Application of a bonding compound suitable forexterior or interior exposure solid surfaces in accordance withthe manufacturers written directions.5.2.3 Where bond cannot be obtained by one or more of themethods in 5.2.2, a furred or self-furring metal p
43、laster baseshall be installed in accordance with Specification C1063.6. Plaster Proportions and Mixing6.1 Proportions:6.1.1 All portland cement plasters shall be mixed andproportioned in accordance with the following tables andaccompanying requirements, using measuring devices ofknown volume with su
44、ccessive batches proportioned alike.6.1.2 Plaster mix used shall be as designated and referencedto Table 1.6.1.3 Base-coat proportions shall be as shown in Table 2 forthe mix specified from Table 1.6.1.3.1 Measurement of MaterialsThe method of measur-ing materials for the plaster shall be such that
45、the specifiedproportions are controlled and accurately maintained. Theweights per cubic foot of the materials are considered to be asfollows:Material Weight, lb/ft3(kg/m3)Portland cement 94 (1505)Blended cement Weight printed on bagMasonry or plastic cement Weight printed on bagHydrated Lime 40 (640
46、)Lime Putty 80 (1280)Sand, Damp and Loose (6.1.3.2) 80 (1280) of dry sand6.1.3.2 For purposes of this specification, a weight of 80 lb(1280 kg) of oven-dried sand shall be used. This is, in mostcases, equivalent to one cubic foot of loose, damp sand.6.1.4 Finish-coat proportions for job-mixed finish
47、 coatsshall be as specified in Table 3.6.1.5 Factory-Prepared Finish CoatsSee 3.2.16.6.1.6 Dash-bond coat proportions shall be 1 volume partportland cement and not more than 2 volume parts of aggregatemixed to a consistency that will permit application as specifiedin 7.1.5.TABLE 1 Plaster BasesPermi
48、ssible MixesNOTESee Table 2 for plaster mix symbols.Property of BaseMixes for Plaster CoatsFirst (Scratch) Second (Brown)Low absorption, such asdense, smooth clay tile,brick, or concreteC C, CL, M, or CMCM or MS CM, MS, or MPPHigh Absorption, such asconcrete masonry, absorp-tive brick, or tileCL CLM
49、MCM or MS CM, MS, or MPPMetal plaster base C C, CL, M, CM, or MSCL CLCM or MS CM, MS, or MMMCP CP or PPPC926 1236.1.7 Admixtures shall be proportioned, mixed, and appliedin accordance with the printed directions of the manufacturer.(See A2.5.)6.2 Mixing:6.2.1 All plaster shall be prepared in a mechanical mixer,using sufficient water to produce a workable consistency anduniform color. (See X1.1.)6.2.2 Base-coat plasters that have stiffened because ofevaporation of water shall be permitted to be tempered onetime only to re
