1、Designation: C 796 04Standard Test Method forFoaming Agents for Use in Producing Cellular ConcreteUsing Preformed Foam1This standard is issued under the fixed designation C 796; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript 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. Scope1.1 This test method furnishes a
3、way of measuring, in thelaboratory, the performance of a foaming chemical to be usedin producing foam (air cells) for making cellular concrete.1.2 This test method includes the following:1.2.1 Manufacture of laboratory quantities of cellular con-crete.1.2.2 Determination of the air content of the fr
4、eshly pre-pared cellular concrete and of the hardened concrete afterhandling in conventional machinery.1.2.3 Determination of the following properties of thehardened concrete: compressive strength, tensile splittingstrength, density, and water absorption. It may not be necessaryto study all of the a
5、bove properties in all cases, depending onthe proposed use of the material.1.3 The values stated in inch-pound units are to be regardedas the standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this
6、 standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.5 The text of this standard references notes and footnoteswhich provide explanatory material. These notes and footnotes(excluding those in tables and figures) sha
7、ll not be consideredas requirements of the standard.2. Referenced Documents2.1 ASTM Standards:2C 88 Test Method for Soundness of Aggregates by Use ofSodium Sulfate or Magnesium SulfateC 150 Specification for Portland CementC 192/C 192M Practice for Making and Curing ConcreteTest Specimens in the Lab
8、oratoryC 495 Test Method for Compressive Strength of Light-weight Insulating ConcreteC 496/C 496M Test Method for Splitting Tensile Strengthof Cylindrical Concrete SpecimensC 511 Specification for Mixing Rooms, Moist Cabinets,Moist Rooms, and Water Storage Tanks Used in theTesting of Hydraulic Cemen
9、ts and ConcretesC 802 Practice for Conducting an Interlaboratory Test Pro-gram to Determine the Precision of Test Methods forConstruction MaterialsC 869 Specification for Foaming Agents Used in MakingPreformed Foam for Cellular Concrete3. Terminology3.1 Definitions:3.1.1 cellular concretea lightweig
10、ht product consisting ofportland cement, cement-silica, cement-pozzolan, lime-pozzolan, or lime-silica pastes, or pastes containing blends ofthese ingredients and having a homogeneous void or cellstructure, attained with gas-forming chemicals or foamingagents (for cellular concretes containing binde
11、r ingredientsother than, or in addition to portland cement, autoclave curingis usually employed).3In cellular concrete the density controlis achieved by substituting macroscopic air cells for all or partof the fine aggregate. Normal-weight coarse aggregate isusually not used but lightweight aggregat
12、es, both fine andcoarse, are often utilized in cellular concrete.3.2 Symbols:Dex1= experimental density of the concrete beforepumping, lb/ft3(kg/m3)Dex2= experimental density of the concrete after pump-ing, lb/ft3(kg/m3)Dth= theoretical density of the plastic mix based onabsolute volume, lb/ft3(kg/m
13、3)Dd= design density of the text mixture, lb/ft3(kg/m3)SGC = specific gravity of cement = 3.151This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.23 on Chemical Admixtures.Current edition approved No
14、v. 1, 2004. Published November 2004. Originallyapproved in 1974. Last previous edition approved in 1997 as C 796 97.2For 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
15、the standards Document Summary page onthe ASTM website.3ACI Committee 116, “Cement and Concrete Terminology,” American ConcreteInstitute, Publication SP-19, 1967, p. 144.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.T = time requir
16、ed to overfill the container, minT1= time required to generate 1 ft3(1 m3) of foam, minV = volume of foam container, ft3(m3)Va= volume of air required in the test batch, ft3(m3)Vc= volume of test specimen (cylinder), ft3(m3)Vf= volume of foam in the test batch, ft3(m3)Vw= volume of water absorbed by
17、 test specimen in 24h, ft3(m3)W1= net weight of foam in overfilled container beforestriking off, lb (kg)W2= net weight of foam in container after striking off,lb (kg)Wc= weight of cement in the test batch, lb (kg)Wf= weight of foam in the test batch, lb (kg)WTW= total weight of water in the test bat
18、ch, includingweight of foam, lb (kg)Wuf= density of foam, lb/ft3(kg/m3)Ww= weight of water added to test batch at mixer, lb(kg)4. Summary of Test Method4.1 This test method includes the following:4.1.1 Manufacture of laboratory quantities of cellular con-crete.4.1.2 Determination of the air content
19、of freshly preparedcellular concrete and of hardened concrete after handling inconventional machinery.4.1.3 Determination of the following properties of hardenedconcrete: compressive strength, tensile splitting strength, den-sity, and water absorption. It may not be necessary to study allof the abov
20、e properties in all cases, depending on the proposeduse of the material.5. Significance and Use5.1 This test method is used to develop data for comparisonor compliance with the requirements of Specification C 869.6. Apparatus6.1 MixerThe mixer shall be a power-driven paddle-typemixer with a capacity
21、 of at least 4 ft3(0.12 m3), an operatingspeed of 40 to 50 r/min (4.2 to 5.2 rad/s), and equipped withrubber wiper blades.6.2 Foam GeneratorThe foam generator shall be alaboratory-sized generator approved by the manufacturer of thefoam being used and shall be similar to the type used in thefield.6.3
22、 PumpThe pump shall be an open or closed throat-typepump and shall be run at 260 to 630 r/min (27.2 to 66.0 rad/s).The pump shall be equipped with a 4.5-ft3(0.13-m3)“ feed”reservoir and 50 ft (15 m) of open-end 1-in. (25-mm) insidediameter rubber hose on the pump discharge, the exit end of thehose b
23、eing at the same height as the pump.6.4 Curing CabinetThe curing cabinet shall be as de-scribed in Specification C511.6.5 MoldsThe cylindrical molds for compression testspecimens shall be as described in the Apparatus section ofTest Method C 495. The molds for all other test specimensshall conform t
24、o the cylinder molds in the Apparatus section ofPractice C 192/C 192M.6.6 Strike-Off Plate for MoldsA14-in. (6-mm) thick, flatsteel plate at least 8 in. (200 mm) longer and 2 in. (50 mm)wider than the diameter of the mold.6.7 ScalesScales and weights shall be accurate to within0.1 % of the weight of
25、 the material being measured.6.8 Compression MachinesCompression testing ma-chines used for compressive strength tests and tensile-splittingstrength tests shall conform to the requirements of TestMethods C 495 and C 496/C 496M, respectively.6.9 Drying OvenThe drying oven shall be as described inTest
26、 Method C88.6.10 Compressed AirA source of compressed air capableof maintaining pressures in the range of 60 to 100 psi (0.4 to0.7 MPa) to 61 psi (60.007 MPa).6.11 Weighing Container for Concrete A machined-steelcontainer of 0.5 ft3(0.014 m3) volume with a flat smooth rim.6.12 Strike-Off Plate for W
27、eighing ContainerA14-in.(6-mm) thick, flat steel plate, at least 8 in. (200 mm) longer and2 in. (50 mm) wider than the diameter of the rim of theweighing container.6.13 Stop WatchA stop watch graduated in seconds andminutes.6.14 CalipersCalipers to span 3, 6, and 12 in. (76, 152,and 305 mm).6.15 Foa
28、m Weighing ContainerA lightweight vessel ofapproximately 2 ft3(0.06 m3) capacity, with a smooth rim forstriking off.6.16 Strike-Off Plate for Foam Weighing ContainerA14-in. (6-mm) thick, flat steel plate at least 8 in. (200 mm)longer and 2 in. (50 mm) wider than the diameter of the rim ofthe contain
29、er.6.17 Small ToolsSmall tools such as a rubber-headedhammer and a trowel shall be provided.7. Materials and Proportions7.1 CementThe cement used shall be Type I or Type IIIportland cement meeting the requirements of SpecificationC 150.7.2 Water-Cement RatioThe water requirement will varywith the ty
30、pe and source of cement. For the purpose of thesetests, w/c = 0.58 for Type I cement and w/c = 0.64 for Type IIIcement shall be used. However, if a particular cement orfoaming agent used with these values of w/c does not producea satisfactory mix, a trial mix or mixes may be made using adifferent wa
31、ter-cement ratio.7.3 Batch QuantitiesThe cement quantity shall be suffi-cient to allow molding all the test specimens from one testbatch. The mixture water-cement ratio determined from 7.2shall be used to make the test batch.7.3.1 The foaming solution in the foam shall be consideredas part of the to
32、tal mixing water. Foam volume shall beadjusted for the batch to produce a density after pumping of 406 3 lb/ft3(641 6 48 kg/m3).8. Procedure8.1 Make an aqueous solution of the foaming agent in thedilution specified by the manufacturer. If the dilution is notspecified, preliminary tests are necessary
33、 to determine theC796042required dilution. A suggested starting point for such tests is 40parts water to 1 part foaming agent, by volume.8.2 Charge the foam generator with the amount of foamingsolution suggested by the manufacturer of the generator.8.3 Connect the generator with the source of compre
34、ssedair, adjusting the pressure to that recommended by the manu-facturer of the foaming agent being tested.8.4 Using the stop watch, calibrate the generator as follows.Weigh the empty foam container and determine its volume.Overfill the container with foam, measuring the time requiredusing a stop wa
35、tch then weigh. Strike off the excess foam,holding the strike-off plate in a horizontal position (plane of theplate horizontal) and moving it across the top of the containerwith a sawing action. Again weigh. Calculate the time requiredper cubic foot (or cubic metre) of foam using the followingequati
36、on:T15 T 3 W2!/W13 V! (1)8.4.1 Calculate also the unit weight of the foam as follows:Wuf5 W2/V (2)8.4.2 Calculate the length of time required to generate therequired volume of foam, VfT1, as follows:VfT15 62.4 VaT1/62.4 2 Wuf! VfT15 1000 VaT1/1000 2 Wuf!(3)8.4.3 Calculate the weight, Wf, of the requ
37、ired volume offoam, VfWuf.NOTE 1The weight of the foam will usually range from 2 to 4 lb/ft3(32 to 64 kg/m3) depending on the foam chemical used. Adjust the unitweight of foam, Wuf, to the manufacturers recommendation if the foamgenerator is adjustable.8.4.3.1 If Type I cement is used, weigh out 58.
38、0 Wflb(26.31 Wfkg) of water, Ww, and 100.0 lb (45.36 kg) of TypeI cement.8.4.3.2 If Type III cement is used, weigh out 64.0 Wflb(29.03 Wfkg) of water, Ww, and 100.0 lb (45.36 kg) of TypeIII cement.8.5 Wet the mixer with water and drain. Add the water, Ww,and start the mixer. Gradually add the cement
39、 (over a period of12 min). With a trowel, break up any lumps of undispersedcement. Mix for 5 min.8.6 While still mixing, add Vfft3(m3) of foam. The requiredfoam time is VfT1. Mix for 2 min after all the foam has beenadded. Discharge the mixer into the pump feed reservoir.Immediately, proceed to 8.7.
40、8.7 WeighingFill a tared weighing container with a rep-resentative sample of the concrete in the reservoir. Beforetaking the sample, carefully mix the concrete in the reservoir toassure better uniformity without entrapping large air bubbles inthe mix. Use a paddle of proper size to reach the bottom
41、of thereservoir. Use a scoop to transfer the concrete to the containerand tap the sides of the container briskly with the rubberhammer during the filling operation. Overfill the container andstrike off the excess concrete, holding the strike-off plate in ahorizontal position (plane of plate horizont
42、al) and moving itacross the top of the container with a sawing motion. Wipe thesurface of the container free of spilled concrete with a cloth.Weigh the full container. Calculate the density of the concreteand record as the density before pumping (Dex1).8.7.1 Pump the batch of concrete through the 50
43、-ft (15-m)hose, discharging it into a sampling basin. From the samplingbasin, take a second density sample as in 8.7, weigh, and recordas the density after pumping (Dex 2).8.8 MoldingImmediately, fill the cylinder molds withconcrete from the sampling basin. Tap the sides of the moldwith the rubber h
44、ammer while the mold is being filled. Theminimum number of specimens required is four cylinders, 3 by6 in. (76 by 152 mm) and ten cylinders 6 by 12 in. (152 by 305mm).8.8.1 As soon as possible after casting, strike off the topsurface of each specimen and cover the specimen with a plasticbag to preve
45、nt evaporation, without marring the surface.8.9 Removal from Molds and Curing Follow the appli-cable requirements of the Test Specimen section of TestMethod C 495 with the following exception: continue airdrying from day 25 to day 28 in place of oven drying thespecimens. Do not oven dry specimens th
46、at are to be load-tested.8.10 Compressive StrengthTest four 3 by 6-in. (76 by152-mm) cylinders for compressive strength in accordancewith Test Method C 495.8.11 Tensile Splitting StrengthTest four 6 by 12-in. (152by 305-mm) cylinders for tensile splitting strength at age 28days in accordance with Te
47、st Method C 496/C 496M, forlightweight concrete.8.12 Oven-Dry WeightDetermine the oven-dry density inaccordance with the section on Oven-Dry Weight of TestMethod C 495. Use three 6 by 12-in. (152 by 305-mm)cylinders from 7.9 at age 28 days.8.13 Water Absorption:8.13.1 Take three 6 by 12-in. (152 by
48、305-mm) specimensfrom 8.9 at age 28 days. Take the dimensions with calipers asdescribed in the Test Specimen Section of Test Method C 495.8.13.2 Submerge the specimens 6 in. (150 mm) below thewater surface. Maintain the water temperature at 73.5 6 3.5 F(23.0 6 2.0 C). Remove from water, allow excess
49、 water to runoff (30 s) and weigh. This is the wet weight of the specimen.9. Calculation9.1 Air Content:9.1.1 Determine the experimental density of the freshlymixed concrete at the mixer, Dex1, and at the pump discharge(end of hose), Dex2, by dividing the net weights of the samplesfrom 8.7 and 8.7.1 by the volume of the container. Record tothe nearest 0.5 lb/ft3(8 kg/m3).9.1.2 Determine the experimental density of the specimensfrom 8.12 before and after drying from the weights andvolumes of the specimens. Use three 6 by 12-in. (152 by30
