1、Designation: C926 15aC926 15bStandard 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 stand
4、ard. 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 Sta
6、ndards: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 Portlan
7、d CementC206 Specification for Finishing Hydrated LimeC207 Specification for Hydrated Lime for Masonry PurposesC219 Terminology Relating to Hydraulic CementC260 Specification for Air-Entraining Admixtures for ConcreteC578 Specification for Rigid, Cellular Polystyrene Thermal InsulationC595 Specifica
8、tion for Blended Hydraulic CementsC631 Specification for Bonding Compounds 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 o
9、f Lathing and Furring to Receive Interior and Exterior Portland Cement-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
10、ElementsE119 Test Methods for Fire Tests of Building Construction and MaterialsE492 Test Method for Laboratory Measurement of Impact Sound Transmission Through Floor-Ceiling Assemblies Using theTapping Machine1 This specification is under the jurisdiction of ASTM Committee C11 on Gypsum and Related
11、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 June 1, 2015July 15, 2015. Published July 2015. Originally approved in 1981. Last previous edition approved
12、in 2015 as C926 15.C926 15a.DOI: 10.1520/C0926-15A.10.1520/C0926-15b.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 page on the ASTM
13、website.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. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult p
14、rior 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 appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1
15、9428-2959. United States12.2 ANSI Standard:A108.1 Specification for Installation of Ceramic Tile33. 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:3.2.1 accelerator, nan admixture that will shorten
16、the setting time of plaster.3.2.2 admixture, na material other than water, aggregate, or basic cementitious material added to the batch before or duringjob mixing.3.2.3 acid etching, nthe cleansing and controlled erosion of a solid surface, using an acid wash.3.2.4 air entrainment, nthe use of an ai
17、r-entraining admixture or air-entraining cementitious material in a plaster mix to yielda controlled quantity of minute (typically between 10 and 1000 m in diameter) disconnected air bubbles in the plaster (seeentrapped air).3.2.5 back wrap, na means of terminating a polymer-modified, fabric reinfor
18、ced cementitious base coat by wrapping thereinforcing mesh, which has been affixed to the substrate onto the outboard surface of the foam plastic core to provide continuityof the reinforced base coat and protection for the foam plastic core.3.2.6 backplaster, nplaster applied to the face of metal la
19、th opposite a previously applied plaster.3.2.7 barrier wall, ntype of wall system that is intended to block or interrupt the movement of water to the interior.3.2.8 bond, nthe state of adhesion between plaster coats or between plaster and plaster base.3.2.9 bonding compound or agent, ncompounds surf
20、ace applied or integrally mixed with plaster to improve the quality ofbond between plaster and plaster base or between plaster coats.3.2.10 cementitious material, na material that, when mixed with water and with or without aggregate, provides the plasticityand the cohesive and adhesive properties ne
21、cessary for placement and the formation of a rigid mass.3.2.11 coat, na thickness of plaster applied in a single operation.3.2.11.1 basecoat, nall plaster applied before the application of the finish coat.3.2.11.2 bedding coat, na plaster coat that receives aggregate or other decorative material imp
22、inged into its surface before itsets.3.2.11.3 brown coat, nin three-coat work, the second coat, applied over the scratch coat. In two-coat work, brown coat refersto the double-up basecoat. In either use, the brown coat is the coat directly beneath the finish coat.3.2.11.4 dash-bond coat, na thick we
23、t mixture of portland cement and water, with or without aggregate, dashed onto thesurface of a plaster base such as smooth monolithic concrete or concrete block surfaces to improve the mechanical key forsubsequent plaster coats.3.2.11.5 double-up coat, nthe brown-coat plaster applied to the scratch
24、coat plaster before the scratch-coat plaster has set.3.2.11.6 finish coat, nthe final layer of plaster applied over basecoat plaster.3.2.11.7 fog coat, na light coat of cement and water, with or without aggregate or color pigment, applied by machine sprayto improve color consistency.3.2.11.8 scratch
25、 coat, nthe first coat of plaster applied to a plaster base.3.2.11.9 skim coat, na thin finish coat applied to an existing plaster surface or other substrate to improve appearance.3.2.11.10 three-coat work, napplication of plaster in three successive coats with time between coats for setting or dryi
26、ng, orboth.3.2.12 cold joint (“joining” or “jointing”), nthe juncture of fresh plaster application adjacent to set plaster, in the same plane.3.2.13 curing, vthe act or processes of producing a moisture environment favorable to cement hydration, resulting in thesetting or hardening of the plaster.3.
27、2.14 drainage wall, na wall system in which the cladding provides a substantial barrier to water intrusion, and which alsoincorporates a concealed water-resistive barrier over which drainage will occur.3.2.15 entrapped air, nunintentional air voids in the plaster generally larger than 1 mm.3.2.16 fa
28、ctory prepared (“mill-mixed” or “ready mixed”), adjpertaining to material combinations that have been formulatedand dry-blended by the manufacturer, requiring only the addition of and mixing with water to produce plaster.3 Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
29、4th Floor, New York, NY 10036.C926 15b23.2.17 fiber, natural or synthetic, nan elongated fiber or strand admixture added to plaster mix to improve cohesiveness orpumpability, or both.3.2.18 floating, vact of compacting and leveling brown-coat plaster to a reasonably true surface plane using a float
30、tool or theact of bringing the aggregate to the surface of finish-coat plaster.3.2.19 key (also mechanical key), nplaster that physically surrounds, penetrates, or deforms to lock onto the perforations orirregularities of the plaster base or previous coat of plaster.3.2.20 metal plaster base, nexpan
31、ded metal lath, or welded or woven wire lath.3.2.21 plaster, nportland cement-based cementitious mixture (see stucco).3.2.22 polymer modified cementitious base coat, nAbase coat containing portland cement modified with chemical admixtures(typically polymer latexes) to improve characteristics of the
32、finished product, such as workability, plasticity, water resistance, andadhesion.3.2.23 required, adjpertaining to a mandatory obligation imposed by a force outside of this specification, such as a buildingcode, project specification, contract, or purchase order.3.2.24 rustication (also “break”), na
33、n interruption or change in plane of a plastered surface.3.2.25 scoring (also known as “scratching”), nthe grooving of the surface of an unset plaster coat to provide a key for asubsequent coat.3.2.26 set, nthe chemical and physical change in plaster as it goes from a plastic, workable state to a ri
34、gid state.3.2.27 solid plaster bases, nsubstrates that do not require a metal plaster base, including cast in place and precast concrete,concrete and stone masonry, clay brick, and tile.3.2.28 stucco, nportland cement-based plaster used on exterior locations.3.2.29 stucco finish, na factory-prepared
35、, dry blend of materials for finish coat applications.3.2.30 temper, vto mix or restore unset plaster with water to a workable consistency.3.2.31 texture, nany surface appearance as contrasted to a smooth surface.4. Materials4.1 Materials shall conform to the requirements of the referenced specifica
36、tions and standards and to the requirements specifiedherein.4.2 Cement:4.2.1 Portland CementSpecification C150, Type I, II, and 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
37、C91, Types N, S, and M. 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), and IT (S70)-(A), asspecified.4.2.6 Plastic CementPlastic C
38、ement shall meet the requirements of Specification C1328, Standard Specification 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. S
39、ee Specifications C206 and C207 for a complete description of a Type “S” hydrated 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
40、 demonstrated performance record in similarconstruction and climate conditions.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, an
41、d free of such amounts of mineral or organic substances as would affect the set, 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.C926 15b35. Requirements for Bases to
42、 Receive Portland Cement-Based Plaster5.1 Metal bases and accessories used to receive plaster 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
43、 matter, which could causebond failure or unsightly discoloration.5.2 Surfaces of solid 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 interfe
44、re with bonding. Conditionswhere the surfaces are out of tolerance shall be corrected prior to the application of the plaster. Form Ferrous-containing form tiesor other obstructions shall be removed or receded a minimum 1/8 in. (3 mm) below the surface of the solid base and treated witha corrosion-r
45、esistant coating. Non-ferrous protuberances shall be permitted to be trimmed back even with the surface of the solidbase.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.5.2.2 Smooth or nonabsorbent solid
46、 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 applied forcefully against the sur
47、face, 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 or more of the methods in 5.2.
48、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 Specification C1063.6. Plaster Pro
49、portions 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 mix 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 th
