1、Designation: C926 14C926 14aStandard 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 1, 2014April 15, 2014. Published May 2014June 2014. Originally approved in 1981. Last previous editi
12、on approved in 20132014 asC92613a.14. DOI: 10.1520/C0926-14.10.1520/C0926-14A.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
13、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. Becau
14、seit 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 appear
15、s 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:3.2.1
16、 acceleratoran admixture that will shorten the setting time of plaster.3.2.2 admixturea material other than water, aggregate, or basic cementitious material added to the batch before or during jobmixing.3.2.3 acid etchingthe cleansing and controlled erosion of a solid surface, using an acid wash.3.2
17、.4 air entrainmentthe use of an air-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 backplasterplaster applied to the f
18、ace of metal lath opposite a previously applied plaster.3.2.6 barrier walltype of wall system that is intended to block or interrupt the movement of water to the interior.3.2.7 bondthe state of adhesion between plaster coats or between plaster and plaster base.3.2.8 bonding compound or agentcompound
19、s surface applied or integrally mixed with plaster to improve the quality of bondbetween plaster and plaster base or between plaster coats.3.2.9 cementitious materiala material that, when mixed with water and with or without aggregate, provides the plasticity andthe cohesive and adhesive properties
20、necessary for placement and the formation of a rigid mass.3.2.10 coata thickness of plaster applied in a single operation.3.2.10.1 basecoatall plaster applied before the application of the finish coat.3.2.10.2 bedding coata plaster coat that receives aggregate or other decorative material impinged i
21、nto its surface before it sets.3.2.10.3 brown coatin 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.3.2.10.4 dash-bond coata thick wet mixture of
22、 portland cement and water, with or without aggregate, dashed onto the surfaceof a plaster base such as smooth monolithic concrete or concrete block surfaces to improve the mechanical key for subsequentplaster coats.3.2.10.5 double-up coatthe brown-coat plaster applied to the scratch coat plaster be
23、fore the scratch-coat plaster has set.3.2.10.6 finish coatthe final layer of plaster applied over basecoat plaster.3.2.10.7 fog coata light coat of cement and water, with or without aggregate or color pigment, applied by machine spray toimprove color consistency.3.2.10.8 scratch coatthe first coat o
24、f plaster applied to a plaster base.3.2.10.9 skim coata thin finish coat applied to an existing plaster surface or other substrate to improve appearance.3.2.10.10 three-coat workapplication of plaster in three successive coats with time between coats for setting or drying, orboth.3.2.11 cold joint (
25、“joining” or “jointing”)the juncture of fresh plaster application adjacent to set plaster, in the same plane.3.2.12 curingthe act or processes of producing a moisture environment favorable to cement hydration, resulting in the settingor hardening of the plaster.3.2.13 drainage walla wall system in w
26、hich the cladding provides a substantial barrier to water intrusion, and which alsoincorporates a concealed water-resistive barrier over which drainage will occur.3.2.14 entrapped airunintentional air voids in the plaster generally larger than 1 mm.3.2.15 factory prepared (“mill-mixed” or “ready mix
27、ed”)pertaining to material combinations that have been formulated anddry-blended by the manufacturer, requiring only the addition of and mixing with water to produce plaster.3.2.16 fiber, natural or synthetican elongated fiber or strand admixture added to plaster mix to improve cohesiveness orpumpab
28、ility, or both.3.2.17 floatingact of compacting and leveling brown-coat plaster to a reasonably true surface plane using a float tool or theact of bringing the aggregate to the surface of finish-coat plaster.3.2.18 key (also mechanical key)plaster that physically surrounds, penetrates, or deforms to
29、 lock onto the perforations orirregularities of the plaster base or previous coat of plaster.3.2.19 metal plaster baseexpanded metal lath, or welded or woven wire lath.3.2.20 plasterportland cement-based cementitious mixture (see stucco).C926 14a23.2.21 requiredpertaining to a mandatory obligation i
30、mposed by a force outside of this specification, such as a building code,project specification, contract, or purchase order.3.2.22 rustication (also “break”) an interruption or change in plane of a plastered surface.3.2.23 scoring (also known as “scratching”) the grooving of the surface of an unset
31、plaster coat to provide a key for asubsequent coat.3.2.24 setthe 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
32、and stone masonry, clay brick, and tile.3.2.26 stuccoportland cement-based plaster used on exterior locations.3.2.27 stucco finisha 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 consistency.3.2.29 textur
33、eany 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 III, as specified. White wh
34、ere 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, and I(SM) as specified.4.2.5 Air-Entrai
35、ning Blended Hydraulic CementSpecification C595, Type IP-A, I(PM)-A, IS-A, and I(SM)-A as specified.4.2.6 Plastic CementPlastic Cement shall meet the requirements of Specification C1328, Standard Specification for Plastic(Stucco) Cement.NOTE 2Plastic cements are not available nationally.4.3 Type “S”
36、 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” hydrated lime.4.4 Aggregates:4.4.1 Sand for Base CoatsSpecification C897. Aggregate failing to mee
37、t 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.4.4.2 PerliteSpecification C35.4.4.3 Sand for Job-Mixed Finish CoatsSpecification C897.4.5 W
38、aterWater 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, the plaster, or any metal in thesystem.4.6 AdmixturesSee 3.2.2 and A2.5.4.7 FibersSpecific
39、ation 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 shall be installed in conformance with Specification C1063, except asotherwise specifi
40、ed.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 bases to receive plaster, such as masonry, stone, cast-in-place or precast concrete shall be
41、 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 prior to the application of the plaster. Form ties or other obstructions shallbe removed or tr
42、immed 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.5.2.2 Smooth or nonabsorbent solid surfaces, such as cast-in-place or precast concrete, shall be prepare
43、d 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,C926 14a35.2.2.2 Application of a dash-bond coat applied forcefully against the surface, left untroweled, undisturbed, and moist cured forat lea
44、st 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 5.2.2, a furred or self-furring metal plaster base shallbe instal
45、led 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 Proportions and Mixing6.1 Proportions:6.1.1 All portland cement
46、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
47、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 accurately maintained. The weights per cubic foot of the materials are considered to be as follow
48、s: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 (12
49、80 kg) of oven-dried sand shall be used. This is, in most cases,equivalent to one cubic foot of loose, damp sand.6.1.4 Finish-coat proportions for job-mixed finish coats shall 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 part portland cement and not more than 2 volume parts of aggregate mixedto a consistency that will permit application as specified in 7.1.5.6.1.7 Admixtures shall be proportioned, mixed, and applied in accordance with the pri
