1、Designation: C926 14aC926 15Standard 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.
2、 A number 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 application of full thickness portland cement-based plaster for exterior(stucco)
3、 and interior work.1.2 This specification sets forth tables for proportioning of various plaster mixes and plaster thickness.NOTE 1General information will be found in Annex A1. Design considerations will be found in Annex A2.1.3 The values stated in inch-pound units are to be regarded as the standa
4、rd. The SI (metric) values given in parentheses areapproximate and are provided for information purposes only.1.4 The text of this specification references notes and footnotes that provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be considered
5、as requirements of the specification.1.5 Details of construction for a specific assembly to achieve the required fire resistance shall be obtained from reports offire-resistance tests, engineering evaluations, or listings from recognized fire testing laboratories.2. Referenced Documents2.1 ASTM Stan
6、dards:2C11 Terminology Relating to Gypsum and Related Building Materials and SystemsC25 Test Methods for Chemical Analysis of Limestone, Quicklime, and Hydrated LimeC35 Specification for Inorganic Aggregates for Use in Gypsum PlasterC91 Specification for Masonry CementC150 Specification for Portland
7、 CementC206 Specification for Finishing Hydrated LimeC207 Specification for Hydrated Lime for Masonry PurposesC219 Terminology Relating to Hydraulic CementC260 Specification for Air-Entraining Admixtures for ConcreteC595 Specification for Blended Hydraulic CementsC631 Specification for Bonding Compo
8、unds for Interior Gypsum PlasteringC897 Specification for Aggregate for Job-Mixed Portland Cement-Based PlastersC932 Specification for Surface-Applied Bonding Compounds for Exterior PlasteringC1063 Specification for Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement
9、Based PlasterC1116 Specification for Fiber-Reinforced Concrete and ShotcreteC1328 Specification for Plastic (Stucco) CementE90 Test Method for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions and ElementsE119 Test Methods for Fire Tests of Building Construction and
10、MaterialsE492 Test Method for Laboratory Measurement of Impact Sound Transmission Through Floor-Ceiling Assemblies Using theTapping Machine2.2 ANSI Standard:A108.1 Specification for Installation of Ceramic Tile31 This specification is under the jurisdiction of ASTM Committee C11 on Gypsum and Relate
11、d Building Materials and Systems and is the direct responsibility ofSubcommittee C11.03 on Specifications for the Application of Gypsum and Other Products in Assemblies.Current edition approved April 15, 2014Feb. 1, 2015. Published June 2014February 2015. Originally approved in 1981. Last previous e
12、dition approved in 2014 asC926C926 14a.14. DOI: 10.1520/C0926-14A.10.1520/C0926-15.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary pag
13、e on the ASTM website.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version.
14、Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section a
15、ppears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Terms shall be defined as in Terminologies C11 and C219, except as modified herein.3.2 Definitions of Terms Specific to This Standard:
16、3.2.1 acceleratoraccelerator, nan admixture that will shorten the setting time of plaster.3.2.2 admixtureadmixture, na material other than water, aggregate, or basic cementitious material added to the batch beforeor during job mixing.3.2.3 acid etchingetching, nthe cleansing and controlled erosion o
17、f a solid surface, using an acid wash.3.2.4 air entrainmententrainment, nthe use of an air-entraining admixture or air-entraining cementitious material in aplaster mix to yield a controlled quantity of minute (typically between 10 and 1000 m in diameter) disconnected air bubbles inthe plaster (see e
18、ntrapped air).3.2.5 backplasterbackplaster, nplaster applied to the face of metal lath opposite a previously applied plaster.3.2.6 barrier wallwall, ntype of wall system that is intended to block or interrupt the movement of water to the interior.3.2.7 bondbond, nthe state of adhesion between plaste
19、r coats or between plaster and plaster base.3.2.8 bonding compound or agentagent, ncompounds surface applied or integrally mixed with plaster to improve thequality of bond between plaster and plaster base or between plaster coats.3.2.9 cementitious materialmaterial, na material that, when mixed with
20、 water and with or without aggregate, provides theplasticity and the cohesive and adhesive properties necessary for placement and the formation of a rigid mass.3.2.10 coatcoat, na thickness of plaster applied in a single operation.3.2.10.1 basecoatbasecoat, nall plaster applied before the applicatio
21、n of the finish coat.3.2.10.2 bedding coatcoat, na plaster coat that receives aggregate or other decorative material impinged into its surfacebefore it sets.3.2.10.3 brown coatcoat, nin three-coat work, the second coat, applied over the scratch coat. In two-coat work, brown coatrefers to the double-
22、up basecoat. In either use, the brown coat is the coat directly beneath the finish coat.3.2.10.4 dash-bond coatcoat, na thick wet mixture of portland cement and water, with or without aggregate, dashed ontothe surface of a plaster base such as smooth monolithic concrete or concrete block surfaces to
23、 improve the mechanical key forsubsequent plaster coats.3.2.10.5 double-up coatcoat, nthe brown-coat plaster applied to the scratch coat plaster before the scratch-coat plaster hasset.3.2.10.6 finish coatcoat, nthe final layer of plaster applied over basecoat plaster.3.2.10.7 fog coatcoat, na light
24、coat of cement and water, with or without aggregate or color pigment, applied by machinespray to improve color consistency.3.2.10.8 scratch coatcoat, nthe first coat of plaster applied to a plaster base.3.2.10.9 skim coatcoat, na thin finish coat applied to an existing plaster surface or other subst
25、rate to improve appearance.3.2.10.10 three-coat workwork, napplication of plaster in three successive coats with time between coats for setting ordrying, or both.3.2.11 cold joint (“joining” or “jointing”)“jointing”), nthe juncture of fresh plaster application adjacent to set plaster, inthe same pla
26、ne.3.2.12 curingcuring, vthe act or processes of producing a moisture environment favorable to cement hydration, resultingin the setting or hardening of the plaster.3.2.13 drainage wallwall, na wall system in which the cladding provides a substantial barrier to water intrusion, and whichalso incorpo
27、rates a concealed water-resistive barrier over which drainage will occur.3.2.14 entrapped airair, nunintentional air voids in the plaster generally larger than 1 mm.3.2.15 factory prepared (“mill-mixed” or “ready mixed”)mixed”), adjpertaining to material combinations that have beenformulated and dry
28、blended by the manufacturer, requiring only the addition of and mixing with water to produce plaster.3.2.16 fiber, natural or syntheticsynthetic, nan elongated fiber or strand admixture added to plaster mix to improvecohesiveness or pumpability, or both.3.2.17 floatingfloating, vact of compacting a
29、nd leveling brown-coat plaster to a reasonably true surface plane using a floattool or the act of bringing the aggregate to the surface of finish-coat plaster.3.2.18 key (also mechanical key)key), nplaster that physically surrounds, penetrates, or deforms to lock onto theperforations or irregulariti
30、es of the plaster base or previous coat of plaster.C926 1523.2.19 metal plaster basebase, nexpanded metal lath, or welded or woven wire lath.3.2.20 plasterplaster, nportland cement-based cementitious mixture (see stucco).3.2.21 requiredrequired, adjpertaining to a mandatory obligation imposed by a f
31、orce outside of this specification, such asa building code, project specification, contract, or purchase order.3.2.22 rustication (also “break”)”), nan interruption or change in plane of a plastered surface.3.2.23 scoring (also known as “scratching”) , nthe grooving of the surface of an unset plaste
32、r coat to provide a key for asubsequent coat.3.2.24 setset, nthe chemical and physical change in plaster as it goes from a plastic, workable state to a rigid state.3.2.25 solid plaster bases, nsubstrates that do not require a metal plaster base, including cast in place and precast concrete,concrete
33、and stone masonry, clay brick, and tile.3.2.26 stuccostucco, nportland cement-based plaster used on exterior locations.3.2.27 stucco finishfinish, na factory-prepared, dry blend of materials for finish coat applications.3.2.28 temper, vto mix or restore unset plaster with water to a workable consist
34、ency.3.2.29 texturetexture, nany surface appearance as contrasted to a smooth surface.4. Materials4.1 Materials shall conform to the requirements of the referenced specifications and standards and to the requirements specifiedherein.4.2 Cement:4.2.1 Portland CementSpecification C150, Type I, II, and
35、 III, as specified. White where specified.4.2.2 Air-Entraining Portland CementSpecification C150, type as specified. White where specified.4.2.3 Masonry CementSpecification C91, Types N, S, and M. White where specified.4.2.4 Blended Hydraulic CementSpecification C595, Type IP, I(PM), IS,IS(70), IL,
36、and I(SM)IT(S70), as specified.4.2.5 Air-Entraining Blended Hydraulic CementSpecification C595, Type IP-A, I(PM)-A, IS-A, and I(SM)-A IP-(A),IS(70)-(A), IL-(A), and IT (S70)-(A), as specified.4.2.6 Plastic CementPlastic Cement shall meet the requirements of Specification C1328, Standard Specificatio
37、n for Plastic(Stucco) Cement.NOTE 2Plastic cements are not available nationally.4.3 Type “S” Hydrated LimeA hydrated lime that contains not more than 8 % unhydrated oxides when tested in accordancewith Test Methods C25. See Specifications C206 and C207 for a complete description of a Type “S” hydrat
38、ed lime.4.4 Aggregates:4.4.1 Sand for Base CoatsSpecification C897. Aggregate failing to meet gradation limits in Specification C897 shall bepermitted to be used, provided the plaster made with this sand has an acceptable demonstrated performance record in similarconstruction and climate conditions.
39、4.4.2 PerliteSpecification C35.4.4.3 Sand for Job-Mixed Finish CoatsSpecification C897.4.5 WaterWater used in mixing, application, and finishing of plaster shall be clean, fresh, suitable for domestic waterconsumption, and free of such amounts of mineral or organic substances as would affect the set
40、 the plaster, or any metal in thesystem.4.6 AdmixturesSee 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 pl
41、aster shall be installed in conformance with Specification C1063, except asotherwise specified.NOTE 3All metal, or PVC, or CPVC plastic members should be free of deleterious amounts of rust, oil, or other foreign matter, which could causebond failure or unsightly discoloration.5.2 Surfaces of solid
42、bases to receive plaster, such as masonry, stone, cast-in-place or precast concrete shall be straight and truewithin 14 in. in 10 ft (2.1 mm/m) and shall be free of form oil or other elements, which would interfere with bonding. Conditionswhere the surfaces are out of tolerance shall be corrected pr
43、ior to the application of the plaster. Form ties or other obstructions shallbe removed or trimmed back even with the surface of the solid base.5.2.1 Solid surfaces shall have the suction (ability to absorb water) or surface roughness, or both, to provide the bond requiredfor the plaster.C926 1535.2.
44、2 Smooth or nonabsorbent solid surfaces, such as cast-in-place or precast concrete, shall be prepared to receive portlandcement plaster by one of the following methods:5.2.2.1 Sandblasting, wire brushing, acid etching, or chipping or a combination thereof,5.2.2.2 Application of a dash-bond coat appl
45、ied forcefully against the surface, left untroweled, undisturbed, and moist cured forat least 24 h, or5.2.2.3 Application of a bonding compound suitable for exterior or interior exposure solid surfaces in accordance with themanufacturers written directions.5.2.3 Where bond cannot be obtained by one
46、or more of the methods in 5.2.2, a furred or self-furring metal plaster base shallbe installed in accordance with Specification C1063. Where metal plaster base is used in areas where bond cannot be obtained byone or more of the methods in 5.2.2, accessories shall be installed in accordance with Spec
47、ification C1063.6. Plaster Proportions and Mixing6.1 Proportions:6.1.1 All portland cement plasters shall be mixed and proportioned in accordance with the following tables and accompanyingrequirements, using measuring devices of known volume with successive batches proportioned alike.6.1.2 Plaster m
48、ix used shall be as designated and referenced to Table 1.6.1.3 Base-coat proportions shall be as shown in Table 2 for the mix specified from Table 1.6.1.3.1 Measurement of MaterialsThe method of measuring materials for the plaster shall be such that the specifiedproportions are controlled and accura
49、tely maintained. The weights per cubic foot of the materials are considered to be as follows: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)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 most cases,equivalent to one cubic foot of l
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