1、Designation: C926 15aStandard 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.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 S
4、I (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 requirem
5、ents 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 Te
6、rminology 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 in Gyp-sum PlasterC91 Specification for Masonry CementC150 Specification for Portland CementC206 Sp
7、ecification for Finishing Hydrated LimeC207 Specification for Hydrated Lime for Masonry Pur-posesC219 Terminology Relating to Hydraulic CementC260 Specification for Air-Entraining Admixtures for Con-creteC578 Specification for Rigid, Cellular Polystyrene ThermalInsulationC595 Specification for Blend
8、ed Hydraulic CementsC631 Specification for Bonding Compounds for InteriorGypsum 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 F
9、urringto Receive Interior and Exterior Portland Cement-BasedPlasterC1116 Specification for Fiber-Reinforced Concrete andShotcreteC1328 Specification for Plastic (Stucco) CementE90 Test Method for Laboratory Measurement of AirborneSound Transmission Loss of Building Partitions andElementsE119 Test Me
10、thods for Fire Tests of Building Constructionand MaterialsE492 Test Method 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
11、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 batch befor
12、e orduring job mixing.1This specification 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
13、 June 1, 2015. Published July 2015. Originally approvedin 1981. Last previous edition approved in 2015 as C926 15. DOI: 10.1520/C0926-15A.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
14、information, refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive
15、, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.3 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
16、 quantity of minute (typically between 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 substrateon
17、to the outboard surface of the foam 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 toblo
18、ck or interrupt the movement of water 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
19、 or between plastercoats.3.2.10 cementitious 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 sing
20、leoperation.3.2.11.1 basecoat, nall 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 t
21、he scratch coat. In two-coat work, 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
22、 as smooth monolithic concrete orconcrete 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 over
23、basecoat plaster.3.2.11.7 fog coat, 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 anexist
24、ing plaster surface or other substrate 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 plast
25、er, in the sameplane.3.2.13 curing, 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 al
26、so incorporates a concealed water-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 dr
27、y-blended by the manufacturer, requiring 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-
28、coat plaster to a reasonably true 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 o
29、r previous coat of plaster.3.2.20 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
30、(typically polymer latexes) to improve characteristicsof the finished product, such as workability, plasticity, waterresistance, and adhesion.3.2.23 required, adjpertaining to a mandatory obligationimposed by a force outside of this specification, such as abuilding code, project specification, contr
31、act, 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 provide a key fora subsequent coat.3.2.26 set, nthe chemical and physical change i
32、n plaster asit goes from a plastic, workable state to a rigid state.C926 15a23.2.27 solid plaster bases, nsubstrates that do not requirea metal plaster base, including cast in place and precastconcrete, concrete and stone masonry, clay brick, and tile.3.2.28 stucco, nportland cement-based plaster us
33、ed 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 surface appearance as contrasted to asmooth surface.4. Materials4.1 Materials
34、 shall conform to the requirements of thereferenced specifications and standards and to the requirementsspecified herein.4.2 Cement:4.2.1 Portland CementSpecification C150, Type I, II, andIII, as specified. White where specified.4.2.2 Air-Entraining Portland CementSpecification C150,type as specifie
35、d. 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, IS(70), IL, and IT(S70), as specified.4.2.5 Air-Entraining Blended Hydraulic CementSpecification C595, Type IP-(A), IS(70)-(A), IL-(A), an
36、d IT(S70)-(A), as specified.4.2.6 Plastic CementPlastic Cement shall meet the re-quirements of Specification C1328, Standard Specification forPlastic (Stucco) Cement.NOTE 2Plastic cements are not available nationally.4.3 Type “S” Hydrated LimeAhydrated lime that containsnot more than 8 % unhydrated
37、oxides when tested in accor-dance with Test Methods C25. See Specifications C206 andC207 for a complete description of a Type “S” hydrated lime.4.4 Aggregates:4.4.1 Sand for Base CoatsSpecification C897. Aggregatefailing to meet gradation limits in Specification C897 shall bepermitted to be used, pr
38、ovided 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 for Job-Mixed Finish CoatsSpecificationC897.4.5 WaterWater used in mixing, application, and finishingof plaster shall be cle
39、an, 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 AdmixturesSee 3.2.2 and A2.5.4.7 FibersSpecification C1116 on alkali-resistant fibers,glass fibers, nylon, polypropylene or
40、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 Specification C1063, exceptas otherwise specified.NOTE 3All metal, or PVC, or CPVC plastic members should be freeof deleteriou
41、s 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, 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 o
42、r 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 other obstructions shall be removed or trimmed backeven with the surface of the solid base.5.2.1 Solid surfaces shall have th
43、e 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 or precast concrete, shall be prepared to receiveportland cement plaster by one of the following methods:5.2.2.1 Sandblasti
44、ng, 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, undisturbed, and moistcured for at least 24 h, or5.2.2.3 Application of a bonding compound suitable forexterior or interior exposure
45、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 plaster baseshall be installed in accordance with Specification C1063.Where metal plaster base is used in areas where bond c
46、annot beobtained by one or more of the methods in 5.2.2, accessoriesshall 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 req
47、uirements, using measuring devices ofknown volume with successive 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
48、 measur-ing materials for the plaster shall be such that 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
49、plastic cement Weight printed on bagHydrated Lime 40 (640)Lime Putty 80 (1280)Sand, Damp and Loose (6.1.3.2) 80 (1280) of dry sandC926 15a36.1.3.2 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 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
