1、Designation: C 956 04Standard Specification forInstallation of Cast-In-Place Reinforced Gypsum Concrete1This standard is issued under the fixed designation C 956; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This specification covers the minimum requirements forthe installation of cast-in-place reinforced gypsum concreteover perman
3、ent formboard.1.2 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.1.3 The text of this standard references notes and footnoteswhich provide explanatory material. These notes and footnotes(excluding those in tables and f
4、igures) shall not be consideredrequirements of the standard.2. Referenced Documents2.1 ASTM Standards:2A 82 Specification for Steel Wire, Plain, for Concrete Re-inforcementA 185 Specification for Steel Welded Wire Reinforcement,Plain, for ConcreteA 568 Specification for Steel, Sheet, Carbon, and Hig
5、h-Strength, Low-Alloy, Hot-Rolled and Cold-Rolled, Gen-eral Requirements forA 653/A 653M Specification for Steel Sheet, Zinc-Coated(Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed)by the Hot-Dip ProcessC 11 Terminology Relating to Gypsum and Related Build-ing Materials and SystemsC 317 Specifica
6、tion for Gypsum ConcreteC 726 Specification for Mineral Fiber Roof InsulationBoardE 72 Test Methods of Conducting Strength Tests of Panelsfor Building Construction2.2 American Concrete Institute Standard:ACI 318 Building Code Requirements for Reinforced Con-crete32.3 American Welding Society Standar
7、d:D1.1 Structural Welding Code Steel43. Terminology3.1 Definitions shall be in accordance with TerminologyC11.3.2 Definitions:3.2.1 primary framing, nstructural members provided tosupport the reinforced gypsum concrete roof deck assembly.3.2.1.1 purlin, na secondary structural member that spansthe p
8、rimary framing members and provides support for sub-purlins.3.2.2 subpurlin, na steel member applied transversely tothe primary framing and purlins to support the formboards andto transmit the dead and live loads from the gypsum concreteslab to the primary framing.3.2.2.1 bulb tee, na subpurlin, hot
9、rolled formed steel,rail-shaped section.3.2.2.2 truss tee, na subpurlin fabricated from steel wireand strip, tee-shaped section.3.2.3 cross tee, na steel tee-shaped section used to supporta formboard end at right angles to the subpurlins where aformboard end does not occur over the purlin or primar
10、yframing.3.2.4 formboard, nsheet material used as a permanentform to support the gypsum concrete.3.2.5 reinforcement, nsteel wire mesh or fabric usedwithin the gypsum concrete slab to provide longitudinal andtransverse strength.3.2.6 double-pouring, nthe application of gypsum con-crete in more than
11、one layer to complete the full slab thickness.See 8.7.4.3.3.2.7 ribbon-pouring or strip-pouring, nthe application ofnarrow ribbons of gypsum concrete, about 10 to 12 in. (254 to1This specification is under the jurisdiction of ASTM Committee C11 onGypsum and Related Building Materials and Systems and
12、 is the direct responsibilityof Subcommittee C11.03 on Specifications for the Application of Gypsum and OtherProducts in Assemblies.Current edition approved May 1, 2004. Published May 2004. Originallyapproved in 1981. Last previous edition C 956 97(2002)e1.2For referenced ASTM standards, visit the A
13、STM 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.3Available from the American Concrete Institute, P.O. Box 19150, Detroit, MI48219.4Available from the Am
14、erican Welding Society, 550 N.W. La Jeune Rd., P.O.Box 351040, Miami, FL 33135.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.305 mm) wide by 1 to 112 in. (25.4 to 38.1 mm) deep, acrossthe width of the formboard at center of span be
15、tween purlins.4. Delivery of Materials4.1 Materials shall be delivered in original packages, con-tainers, or bundles bearing the brand name and name ofproducer or seller. Bulk materials shall be delivered with thebrand name and name of the producer or seller shown on theaccompanying bills of lading.
16、5. Storage of Materials5.1 All materials shall be stored in a manner that preventsdamage before use. When stored under tarpaulins, ventilationshall be provided to prevent moisture accumulation under thetarpaulin.5.2 Formboard shall be stored flat and off the ground.Handling and stacking shall be don
17、e in such a manner toprevent damage to face, ends, and edges and keep dry until use.5.3 When it is necessary to store gypsum concrete at the jobsite, the gypsum concrete shall be stored off the ground andkept dry until use.6. Environmental Conditions6.1 The minimum temperature at which gypsum concre
18、te ismixed and placed is not specified. Gypsum concrete shall notbe mixed with water containing ice crystals.NOTE 1An exothermic reaction during setting ensures completehydration before freezing.7. Materials7.1 Subpurlins:7.1.1 Subpurlins shall be designed to support live and deadloads of the roof d
19、eck.7.1.2 Hot-rolled and cold-rolled steel shapes other than bulbtees or truss tees shall meet the requirements of this specifica-tion for subpurlins.7.2 Cross Tees, shall be not less than 114 in. (31.75 mm)wide by12 in. (12.7 mm) high, fabricated from not less than 26gage zinc-coated steel conformi
20、ng to Specifications A 653/A 653M or A 568.7.3 Formboard:7.3.1 Mineral Fiber Formboard, Specification C 726, notless than34 in. (19.0 mm) thick nor more than 3 in. (76 mm)thick. It shall sustain a uniform load of 20 lb/ft2(97 kg/m2).7.3.1.1 Mineral fiber formboard shall be tested in accor-dance with
21、 the transverse loading test of Test Methods E 72.7.3.1.2 The test specimen shall be uniformly loaded andsupported at both edges and ends. The test specimens shall besupported at the perimeter with a frame providing 1 in. (25.4mm) bearing on ends and12 in. (12.7 mm) bearing on edgesand 7 in. (177.8
22、mm) nominal clearance from the bed of theapparatus.7.3.1.3 For formboards34 in. (19.0 mm) thick, test speci-mens shall be 48 in. (1200 mm) long by 24 in. (600 mm) wide.7.3.1.4 For formboards 1 in. (25.4 mm) thick or greater, testspecimens shall be 48 in. (1200 mm) long by 32 in. (800 mm)wide.7.4 Rei
23、nforcement, Specification A 82, shall be fabricatedfrom zinc-coated (galvanized) welded or woven steel wiremesh or fabric having an effective cross-sectional area of notless than 0.026 in.2(16.77 mm)2per foot of slab width.Reinforcement shall be free of rust, scale, or other materialsthat reduce bon
24、d to the gypsum concrete.7.4.1 Hexagonal Reinforcing Mesh, shall be fabricated from2 in. (50.8 mm) hexagonal mesh formed of not less than 0.0410in. (1.04 mm) diameter wires with longitudinal wires not lessthan 0.0625 in. (1.59 mm) in diameter, spaced not more than 3in. (76.2 mm) on centers. Steel wi
25、re for fabricating wire meshand fabricSpecification A 82.7.4.2 Rectangular Reinforcing Fabric, Specification A 185,shall be fabricated from longitudinal wires not less than 0.1055in. (2.68 mm) in diameter spaced not more than 4 in. (102 mm)on centers and transverse wires not less than 0.0800 in. (2.
26、03mm) in diameter spaced not more than 8 in. (203 mm) oncenters.7.5 Gypsum Concrete, Specification C 317, Class A.7.6 Water, shall be potable and free of substances that couldadversely affect the gypsum concrete.7.7 Expansion Filler Strip, shall be not less than34 in. (19mm) thick and equal in heigh
27、t to the abutting gypsum concreteand of the type specified by the producer of the gypsumconcrete.8. Installation8.1 Installation of Subpurlins:8.1.1 Installation, Normal:8.1.1.1 SubpurlinsThe subpurlins shall be placed trans-versely to the purlins and primary framing and shall be spacedto suit the s
28、ize of the formboards specified. Subpurlins shall beof sufficient length so that their joints occur over purlins orprimary framing. Subpurlin joints shall be alternated so that thejoints are staggered one purlin space.8.1.1.2 Subpurlins shall be welded to purlins and steelprimary framing with18 in.
29、3.2 mm) fillet welds not less than12 in. (12.7 mm) long on alternate sides of the subpurlin at eachintersection with purlins. Except as otherwise specified, weld-ing shall be in accordance with AWS D1.1. Where primaryframing is of wood, nails not less than 16d shall be used oneach side of the subpu
30、rlins at each intersection. The nails shallbe bent over approximately34 in. (19 mm) to securely clinchthe flange of the subpurlin.8.1.2 Installation Seismic:8.1.2.1 SubpurlinsThe subpurlins shall be welded at eachintersection with the purlins with18-in. (3.2-mm) fillet weldsnot less than 1 in. (25.4
31、 mm) long, on one side. Both sides ofthe subpurlin shall be welded with18-in. fillet welds not lessthan 2 in. (50.8 mm) long where subpurlin joints occur over thepurlin. Both sides of the subpurlin shall be welded with18-in.fillet welds not less than 2 in. long at shear transfer points andat interse
32、ctions with exterior frame.8.1.3 Maximum SpansRefer to X2.1.3.8.2 Cross TeesCross tees shall be provided where form-board ends are supported by purlins or the primary framing.8.3 FormboardsFormboards shall be located face downon the flanges of the supporting members and with the ends ontop of the pu
33、rlins.8.3.1 Gypsum concrete shall not be poured over formboardswhich have been wetted by rain or snow.C9560428.3.2 The gypsum concrete shall be poured on the same daythe formboards are installed.8.4 ReinforcementThe mesh of wire fabric shall be lo-cated with the main longitudinal wires at right angl
34、es to thesubpurlins and adjacent to the formboard at midspan betweenthe purlins. Ends of the reinforcement shall be lapped not lessthan 4 in. (102 mm) or one mesh, whichever is greater.8.4.1 Edges shall be butted, not lapped, unless required forfire rated or horizontal diaphragm construction. Reinfo
35、rcementshall be cut to fit at walls, curbs, and openings, folded over onto itself, and extended into all areas when gypsum concrete isto be placed.8.5 Expansion Filler StripsExpansion filler strips shall beplaced continuously against the walls, curbs, nailers, or otherrigid surfaces that gypsum conc
36、rete will abut.8.6 Expansion JointsExpansion joints shall be located atexpansion joints found in the main structure, at a maximum of200 ft (61 m) on center in a direction parallel to the subpurlinson large buildings, at intersections of wings on L-, U-, T-, andH-shaped buildings and, wherever the ro
37、of framing changesdirection. See X1.5.5.8.7 Gypsum Concrete Mixing and Placement:8.7.1 GeneralAll equipment, including mixers, pumps,hoses, tools, and screeds shall be kept clean and free of setgypsum concrete throughout the placement operation.8.7.2 ProportioningThe ratio of water to gypsum con-cre
38、te shall be that specified by the producer of the gypsumconcrete; additional water is prohibited. Volumetric or meter-ing devices shall be used to ensure accurate measurement.8.7.3 MixingMixing shall be thorough but not overmixed.The slurry shall be discharged into placement equipmentimmediately aft
39、er completion of mixing to avoid buildup of setmaterial.8.7.3.1 Calcium chloride or other admixtures shall not beadded to the gypsum concrete.8.7.4 Placement:8.7.4.1 GeneralTo avoid exposure to inclement weatherand physical abuse, gypsum concrete shall be placed the sameday as the installation of th
40、e formboard and reinforcementmaterials.8.7.4.1.1 The deck shall be poured in sections of similarsize.8.7.4.2 Screeds GroundsScreeds, such as metal bars orwood strips, shall be spaced approximately 10 ft (3050 mm)apart at right angles on top of the subpurlins at a height thatwill allow the gypsum con
41、crete slurry to be leveled at thespecified thickness.8.7.4.2.1 Gypsum concrete cants, curbs, and drainage slopesshall be placed to the design thickness. Curbs around openingsshall be permitted to be formed with the formboard.8.7.4.3 The gypsum concrete shall be discharged into place-ment equipment i
42、mmediately after completion of mixing.8.7.4.3.1 The slurry shall be poured or discharged not morethan 24 in. (600 mm) off the formboard to minimize impact andallowed to build to full thickness in one continuous operation.Double pouring shall not be permitted.8.7.4.3.2 As soon as the slurry has stiff
43、ened enough to holda full level, it shall be screeded to a true, even surface using asmooth, rigid straight-edge.8.7.4.4 Place gypsum concrete cants, curbs, and drainageslopes to the design thickness. Curbs around openings shall bepermitted to be formed with the formboard.8.8 Roof OverhangsGypsum co
44、ncrete shall not be placedon roof overhangs, eaves, or other similar locations, onformboards unless the underside is protected against directwetting by a suitable facia drip cap overhang.8.9 DryingConstruction moisture shall be removed fromthe building to permit drying of completed gypsum concretesl
45、ab, providing heat and ventilation where required. See X1.3.8.10 Protection of Completed SlabGypsum concrete isnot a finished traffic or weather protective surface. The top sideof the completed gypsum concrete slab shall be protected witha permanent waterproof covering.9. Keywords9.1 calculation of
46、diaphragm shear; gypsum concrete; gyp-sum roof deckAPPENDIXES(Nonmandatory Information)X1. GENERAL INFORMATIONX1.1 Limitations of UseX1.1.1 Roof Shapes and DesignsGypsum roof decksmeeting this specification can be installed on flat, warped,sawtooth, curved, or pitched roofs.NOTE X1.1On flat roofs, a
47、 minimum pitch of18 in./ft (10.4 mm/m) isrecommended.X1.1.2 Moisture ExposureCast-in-place gypsum concreteis not recommended for general use in occupancies where itmay be exposed to sustained relative humidity greater than90 % or condensing moisture. The producer of the gypsumconcrete should be cons
48、ulted regarding limitations of use inhigh humidity occupancies.X1.1.3 Temperature ExposuresWhere intermittent or ex-tended exposures to high temperatures are to be expected, suchas in slabs directly exposed to radiant heat over furnaceC956043breachings, the gypsum concrete producer should be consult
49、edfor specific recommendations.X1.1.4 Acid FumesIf acid fumes are to be encountered,the producer of the gypsum concrete should be consulted forhis specific recommendations.X1.1.5 Surface ProtectionGypsum concrete decks shallnot be used as a finished surface to bear traffic or other loads.Protective permanent waterproof coverings shall be installed assoon as possible after completion of the slab.X1.1.6 Welding PrecautionsExcept as modified in thebody of this specification, welding shall be in accordance withAWS D1.1. Welding will not be
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