1、Designation:C 79/C 79M 04aStandard Specification forGypsum Sheathing Board1This standard is issued under the fixed designation C 79/C 79M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year of last revision.A number in parenthes
2、es indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope*1.1 This specification covers gypsum sheathing with awater-resistant core,whic
3、h is designed to be used as asheathing on buildings.NOTE1Specification C 1280 contains application procedures forgypsum sheathing board.1.2 The values stated in either inch-pound or SI(metric)units are to be regarded separately as the standard.Within thetext,the SI units are shown in brackets.The va
4、lues stated ineach system shall be used independently of the other.Valuesfrom the two systems shall not be combined.2.Referenced Documents2.1 ASTM Standards:2C 11 Terminology Relating to Gypsum and Related Build-ing Materials and SystemsC 473 Test Methods for Physical Testing of Gypsum PanelProducts
5、C 645 Specification for Nonstructural Steel Framing Mem-bersC 1264 Specification for Sampling,Inspection,Rejection,Certification,Packaging,Marking,Shipping,Handling,and Storage of Gypsum BoardC 1280 Specification for Application of Gypsum SheathingE 119 Test Methods for Fire Tests of Building Constr
6、uctionand Materials3.Terminology3.1 Definitions used in this specification shall be in accor-dance with Terminology C 11.4.Materials and Manufacture4.1 Gypsum sheathing shall consist of a noncombustiblewater-resistant core,essentially gypsum,surfaced on both theface and the back with water-repellent
7、 paper bonded to thecore.4.2 Gypsum Sheathing,Type X(Special Fire-Resistant),designates gypsum sheathing complying with this specificationthat provides not less than 1-h fire-resistance rating for boards58in.15.9 mm thick or34-h fire-resistance rating for boards12in.12.7 mm thick,applied parallel wi
8、th and on each sideof load bearing 2 by 4 wood studs spaced 16 in.406 mm oncenters with 6d coated nails,178in.48 mm long,0.0915-in.2.3-mm diameter shank,14-in.6.4-mm diameter heads,spaced 7 in.178 mm on center with gypsum sheathing jointsstaggered 16 in.406 mm on each side of the partition andtested
9、 in accordance with Test Methods E 119.NOTE2Consult producers for independent test data on assemblydetails and fire resistance ratings for other types of construction.See firetest reports,or listings from recognized fire testing laboratories,forassembly particulars,materials,and ratings.5.Physical P
10、roperties5.1 Specimens shall be taken from the samples obtained inaccordance with 8.1.5.2 Specimens shall be tested in accordance with TestMethods C 473.5.2.1 Flexural StrengthThe specimens shall be tested faceup and face down.The average breaking load shall be not lessthan the following:1This speci
11、fication is under the jurisdiction of ASTM Committee C11 onGypsum and Related Building Materials and Systems and is the direct responsibilityof Subcommittee C11.01 on Specifications and Test Methods for Gypsum Products.Current edition approved May 1,2004.Published June 2004.Originallyapproved in 193
12、0.Last previous edition approved in 2004 as C 79/C 79M 04.2For 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 website.1*A Summ
13、ary 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.NOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)f
14、or the latest information Method AMethod AMethod BMethod BThicknessBearing EdgesPerp to PanelLengthBearing EdgesPar to PanelLengthBearing EdgesPerp to PanelLengthBearing EdgesPar to PanelLengthin.mmlbf Nlbf Nlbf Nlbf N389.580 35630 13377 34326 11641010.288 39132 14285 37828 1251212.7110 48940 178107
15、 47636 1605815.9150 66750 222147 65446 2055.2.2 Humidified DeflectionThe specimens shall have anaverage deflection of not more than the following:Thicknessin.mmDeflectioneighths of an inch mm389.515 4841010.212 381212.710 325815.95 165.2.3 Core,End,and Edge HardnessThe specimens shallhave an average
16、 hardness of not less than 15 lbf 67 N whentested by Method A and 11 lbf 49 N when tested by MethodB.5.2.4 Nail Pull ResistanceThe specimens shall have anaverage nail-pull resistance of not less than the following:Thicknessin.mmMethod Albf NMethod Blbf N389.560 26756 24941010.270 31267 2981212.780 35677 3435815.990 40087 3875.2.5 Water Resistance of Gypsum SheathingThe speci-mens shall have an average water absorption of not more than10 weight%after 2-h immersion.5.2.6 Surface Water Absorption o
