1、Designation: C956 04 (Reapproved 2015)Standard Specification forInstallation of Cast-In-Place Reinforced Gypsum Concrete1This standard is issued under the fixed designation C956; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () 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 conc
3、reteover permanent 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
4、in tables and figures) shall not be consideredrequirements of the standard.2. Referenced Documents2.1 ASTM Standards:2A82/A82M Specification for Steel Wire, Plain, for ConcreteReinforcement (Withdrawn 2013)3A185/A185M Specification for Steel Welded WireReinforcement, Plain, for Concrete (Withdrawn 2
5、013)3A568/A568M Specification for Steel, Sheet, Carbon,Structural, and High-Strength, Low-Alloy, Hot-Rolled andCold-Rolled, General Requirements forA653/A653M Specification for Steel Sheet, Zinc-Coated(Galvanized) or Zinc-Iron Alloy-Coated (Galvannealed)by the Hot-Dip ProcessC11 Terminology Relating
6、 to Gypsum and Related BuildingMaterials and SystemsC317/C317M Specification for Gypsum ConcreteC726 Specification for Mineral Wool Roof Insulation BoardE72 Test Methods of Conducting Strength Tests of Panelsfor Building Construction2.2 American Concrete Institute Standard:ACI 318 Building Code Requ
7、irements for Reinforced Con-crete42.3 American Welding Society Standard:D1.1 Structural Welding Code Steel53. 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 a
8、ssembly.3.2.1.1 purlin, na secondary structural member that spansthe primary 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 c
9、oncreteslab to the primary framing.3.2.2.1 bulb tee, na subpurlin, hot-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 su
10、bpurlins where aformboard end does not occur over the purlin or primaryframing.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.
11、2.6 double-pouring, nthe application of gypsum con-crete in more than 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
12、 Committee C11 onGypsum and Related Building Materials and Systems and is the direct responsibilityof Subcommittee C11.03 on Specifications for theApplication of Gypsum and OtherProducts in Assemblies.Current edition approved Oct. 1, 2015. Published October 2015. Originallyapproved in 1981. Last pre
13、vious edition approved in 2010 as C956 04 (2010).DOI: 10.1520/C0956-04R15.2For 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
14、ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available fromAmerican Concrete Institute (ACI), P.O. Box 9094, FarmingtonHills, MI 48333-9094, http:/www.concrete.org.5Available from American Welding Society (AWS), 550 NW LeJeune Rd.,Miami, FL 33126,
15、 http:/www.aws.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1305 mm) wide by 1 to 112 in. (25.4 to 38.1 mm) deep, acrossthe width of the formboard at center of span between purlins.4. Delivery of Materials4.1 Materials shall be
16、delivered in original packages,containers, 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.5. Storage of Materials5.1 All materials shall be stored in a m
17、anner 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 done in such a manner toprevent damage to face, ends, and edges an
18、d 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 concrete ismixed and placed is not specified. Gypsum concrete shall n
19、otbe 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 deck.7.1.2 Hot-rolled and cold-rolled steel shapes other than bu
20、lbtees 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 conforming to Specifications A653/A653M or A568/A568M.7.3 Formboard:7.3
21、.1 Mineral Fiber Formboard, Specification C726, 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 the transverse loading test of Test Methods E72.7.3.1.2 The
22、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 mm) nominal clearance from the bed of theapparatus.7.3.1.3 For
23、 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 Reinforcement, Specification A82/A82M, shall be fab-ricated from
24、zinc-coated (galvanized) welded or woven steelwire mesh or fabric having an effective cross-sectional area ofnot less than 0.026 in.2(16.77 mm)2per foot of slab width.Reinforcement shall be free of rust, scale, or other materialsthat reduce bond to the gypsum concrete.7.4.1 Hexagonal Reinforcing Mes
25、h, 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 wire for fabricating wire meshand fabricSpecification A82/
26、A82M.7.4.2 Rectangular Reinforcing Fabric, Specification A185/A185M, shall be fabricated from longitudinal wires not lessthan 0.1055 in. (2.68 mm) in diameter spaced not more than 4in. (102 mm) on centers and transverse wires not less than0.0800 in. (2.03 mm) in diameter spaced not more than 8 in.(2
27、03 mm) on centers.7.5 Gypsum Concrete, Specification C317/C317M, ClassA.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 height to the abutting gypsum concreteand of th
28、e 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 size of the formboards specified. Subpurlin
29、s 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. (3.2 mm) fillet welds not less than12 in.
30、(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 subpurlins at each intersection. The nails shal
31、lbe 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 mm) long, on one side. Both sides ofthe s
32、ubpurlin 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 intersections with exterior frame.8.1.3 Maximum S
33、pansRefer to X2.1.3.8.2 Cross TeesCross tees shall be provided where form-board ends are supported by purlins or the primary framing.C956 04 (2015)28.3 FormboardsFormboards shall be located face downon the flanges of the supporting members and with the ends ontop of the purlins.8.3.1 Gypsum concrete
34、 shall not be poured over formboardswhich have been wetted by rain or snow.8.3.2 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 angles to thesubpurlins and adjacent t
35、o 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. Reinforcementshall be cut to fit at wall
36、s, 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 concrete will abut.8.6 Expansion Joint
37、sExpansion 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 roof framing changesdirection. See X
38、1.5.5.8.7 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 concreteshall be that specified by the pr
39、oducer of the gypsum concrete;additional water is prohibited. Volumetric or metering devicesshall be used to ensure accurate measurement.8.7.3 MixingMixing shall be thorough but not overmixed.The slurry shall be discharged into placement equipmentimmediately after completion of mixing to avoid build
40、up 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 the formboard and reinforcementmaterials
41、.(a) The deck shall be poured in sections of similar size.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 concrete slurry to be leveled at thespecified
42、thickness.(a) Gypsum concrete cants, curbs, and drainage slopes shallbe placed to the design thickness. Curbs around openings shallbe permitted to be formed with the formboard.8.7.4.3 The gypsum concrete shall be discharged into place-ment equipment immediately after completion of mixing.(a) The slu
43、rry shall be poured or discharged not more than24 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.(b) As soon as the slurry has stiffened enough to hold a fulllevel, it shall be screeded to a tr
44、ue, 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 concrete shall not be placedon roof overhangs, eaves, or other
45、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 concreteslab, providing heat and ventilation where required. See X1.3.8
46、.10 Protection of Completed SlabGypsum concrete is nota finished traffic or weather protective surface. The top side ofthe completed gypsum concrete slab shall be protected with apermanent waterproof covering.9. Keywords9.1 calculation of diaphragm shear; gypsum concrete; gyp-sum roof deckAPPENDIXES
47、(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 minimum pitch of18 in./ft (10.4 mm/m) isrecommended.X1.1.2 M
48、oisture 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 consulted regarding limitations of use inhigh humidity occupancie
49、s.C956 04 (2015)3X1.1.3 Temperature ExposuresWhere intermittent or ex-tended exposures to high temperatures are to be expected, suchas in slabs directly exposed to radiant heat over furnacebreachings, the gypsum concrete producer should be consultedfor 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.P
