1、Designation: C 472 99 (Reapproved 2004)Standard Test Methods forPhysical Testing of Gypsum, Gypsum Plasters and GypsumConcrete1This standard is issued under the fixed designation C 472; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year 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 These test methods co
3、ver the physical testing of gyp-sum, gypsum plasters, and gypsum concrete.1.2 The test methods appear in the following sections:SectionsPrecautions for Physical Tests 4Reagents and Materials 5Free Water 6Fineness 7Normal Consistency of Gypsum Plaster 8Normal Consistency of Gypsum Concrete 9Setting T
4、ime 10Setting Time (Temperature Rise Method) 11Compressive Strength 12Density 131.3 The values regarded as the standard are either ininch-pound units or SI (metric). The values stated first shall beregarded as the standard. Values following in parentheses areapproximate and are provided for informat
5、ion purposes only.1.4 The text of this standard references notes and footnoteswhich provide explanatory material. These notes and footnotes(excluding those in tables and figures) are not requirements ofthe standard.1.5 This standard does not purport to address all of thesafety concerns, if any, asso
6、ciated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. For a specificprecautionary statement, see X1.2.1.2. Referenced Documents2.1 ASTM Standards:2C11 Te
7、rminology Relating to Gypsum and Related Build-ing Materials and SystemsC 778 Specification for Standard SandE11 Specification for Wire Cloth and Sieve for TestingPurposes3. Terminology3.1 Definitions:3.1.1 For useful definitions refer to Terminology C11.4. Precautions for Physical Tests4.1 Gypsum p
8、roducts are greatly affected by small amountsof impurities introduced by careless laboratory manipulation.In order to obtain accurate results, it is absolutely essential toobserve the following precautions:4.1.1 Keep all apparatus thoroughly clean. Remove alltraces of set plaster.NOTE 1For mixing pa
9、stes and mortars, a 500-ml rubber dental bowlis a convenience.NOTE 2Use care when drying gypsum, gypsum plasters, or gypsumconcrete. Exceeding the specified drying temperatures may calcine thespecimens, which will cause inaccurate test results.5. Reagents and Materials5.1 Distilled or Deionized Wate
10、rfree of chlorides andsulfates at a temperature of 21 6 1C (70 6 2F).5.2 Standard Sand Specification C 778, 2030 sand.6. Free Water6.1 Significance and UseThis test method determines thefree water contained in gypsum, gypsum plasters, and gypsumconcrete samples, and prepares the sample for subsequen
11、ttesting.6.2 Apparatus:6.2.1 Balance, capable of weighing not less than 500 g ata precision of 0.1 g.6.2.2 Drying Oven, set at 45 6 3C.6.2.3 Desiccator, containing calcium chloride or equiva-lent desiccant.6.3 Procedure:1These test methods are under the jurisdiction of ASTM Committee C11 onGypsum an
12、d Related Building Materials and Systems and are the direct responsi-bility of Subcommittee C11.01 on Specifications and Test Methods for GypsumProducts.Current edition approved May 1, 2004. Published June 2004. Originallyapproved in 1961. Last previous edition approved in 1999 as C 47298.2For refer
13、enced 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West
14、 Conshohocken, PA 19428-2959, United States.6.3.1 Weigh a sample of not less than 500 g of the materialas received to the nearest 0.1 g and spread it to a thin layer ina suitable-vessel. Place in an oven (6.2.2) and dry for 2 h; thencool in a desiccator (6.2.3) and weigh again.6.3.2 Retain the dried
15、 sample in an airtight container untilused for the fineness test (Section 7).6.4 ReportReport the loss in weight as a percentage of theoriginal weight of the sample as received to a precision of0.1%.6.5 Precision and BiasThe precision and bias of the freewater test method have not been determined.7.
16、 Fineness7.1 Significance and UseThis test method covers a pro-cedure for determining the fineness of gypsum and gypsumplasters and is used to determine compliance with gypsum andgypsum plaster specifications. The degree of correlation be-tween the results of this test method and service performance
17、has not been determined.7.2 Apparatus:7.2.1 Sieves, as required by a particular gypsum or gypsumplaster specification, in accordance with Specification E11.7.2.2 Balance, capable of weighing not less than 1000 g ata precision of 0.1 g.7.2.3 Mechanical Sieving Machine7.3 Procedure:7.3.1 Determine fin
18、eness by sieving a known weight of thedried sample through sieves of the specified sizes (Note 3 andNote 4). The size of the sample to be used in determiningfineness depends upon the particle size of the material. If thematerial will pass a 6.3-mm (14-in.) sieve, a 100-g sample willbe sufficient; if
19、 the largest particles are more than 25 mm (1 in.)in diameter, use not less than a 1000-g sample. With theselimitations the size of sample to be used is left to the discretionof the operator. Shake the sample through each sieve with aslittle abrasion as possible (Note 5). Weigh the amount ofmaterial
20、 retained on each sieve and calculate the fineness,expressed as a percentage of the weight of the original sample.7.3.2 If a mechanical sieving machine is used, make a seriesof tests at one minute intervals, with each type of material andsieve size combination to be used. When not more than 0.5 gpas
21、ses each sieve in a one minute interval, use that time as thestandard sieving time for that test procedure on that machine.NOTE 3For suggested method of sieving gypsum through a 45-m(No. 325) sieve, see Appendix X1.NOTE 4The sizes of the sieves to be used are given in the specifica-tions of ASTM cov
22、ering the particular product in question.NOTE 5When sieving by hand through a 150-m (No. 100) sieve, usea lateral motion, and tap the side of the sieve with the palm of the hand.Continue without brushing until not more than 0.5 g passes through during1 min of sieving. If the sieve openings become cl
23、ogged, transfer theretained material temporarily to another vessel, invert the sieve over asheet of paper on the table and tap it sharply against the table. Thentransfer all the retained material back into the sieve and continue sieving.7.4 ReportReport the percent by weight retained on eachsieve or
24、 passing particular sieves in accordance with thematerial specification to the nearest full percentage point.7.5 Precision and BiasThe precision and bias of thefineness test method have not been determined.8. Normal Consistency of Gypsum Plaster8.1 Significance and UseThis test method is used todete
25、rmine the volume of water required for mixing gypsumplaster when performing the setting time and compressivestrength tests.8.2 Apparatus:8.2.1 Modified Vicat ApparatusThe modified Vicat appa-ratus (Fig. 1)3shall consist of a bracket, A, bearing a movablebrass rod, B, 6.3 mm in diameter and of suitab
26、le length to fit theVicat Bracket. A conical plunger made of aluminum with anapex angle of 53 08 min and a height of 45 mm shall beattached to the lower end of the rod. The total weight of the rodand plunger shall be 35 g.Ameans shall be provided for addinga weight, G, to the rod, increasing the tot
27、al weight to 50 g. Therod shall be capable of being held in any position by a screw,E. The rod shall have a mark, D, midway between the endswhich moves under a scale, F, graduated in millimetres,attached to the bracket, A.8.2.2 MoldThe conical ring mold shall be made of anoncorroding, nonabsorbent m
28、aterial, and shall have an insidediameter of 60 mm at the base and 70 mm at the top and aheight of 40 mm.3This method is described by Kuntze, R. A., “An Improved Method for theNormal Consistency of Gypsum Plasters,” ASTM Bulletin No. 246, ASTM, May1960, p. 35.AHinged support bracket DGraduation mark
29、BPlunger support rod ELock screwCConical plunger FModified scaleGWeightFIG. 1 Modified Vicat Apparatus (Conical Plunger Method)C 472 99 (2004)28.2.3 Base PlateThe base plate for supporting the ringmold shall be of plate glass and about 100 mm square.8.2.4 Balance, capable of weighing not less than 5
30、00 g at aprecision of 0.1 g.8.2.5 Graduated Cylinder, shall be made to deliver theindicated volume at 20C (68F) and shall be subdivided to notless than 1 mL.8.3 Procedure:8.3.1 Clean the plunger, mold, and base plate of the modi-fied Vicat apparatus. Apply a thin coat of petroleum jelly orother suit
31、able lubricant to the upper surface of the base plate inorder to prevent leaks during the test.8.3.2 Sift a weighed quantity of the sample (200 to 300 g asrequired to fill the mold) into a known volume of water (See5.1). If the plaster is unretarded, add to the mixing water 0.2 gof sodium citrate pe
32、r 100 g of sample. After allowing thesample to soak for 2 min, stir the mixture for 1 min to an evenfluidity. Pour this sample into the ring mold, work slightly toremove air bubbles, and then strike off flush with the top of themold. Wet the plunger of the modified Vicat apparatus andlower it to the
33、 surface of the sample at approximately the centerof the mold. Read the scale and release the plunger immedi-ately.After the rod has settled, read the scale again. Make threedeterminations on each mix, care being taken to have the moldcompletely filled and the plunger clean and wet.8.3.3 Test gypsum
34、 molding plaster and gypsum gaugingplaster with different amounts of water until a penetration of 306 2 mm is obtained. Use the rod and plunger for thisdetermination weighing 35 g.8.3.4 Test all gypsum mixtures containing aggregates withdifferent amounts of water until a penetration of 20 6 2mmisobt
35、ained. Add weight to the rod and plunger to bring the totalweight to 50 g for these determinations.8.3.5 Mix gypsum neat plaster with standard sand (see 5.2)in the ratio of 200 g of sand to 100 g of plaster before testingfor normal consistency.8.4 Report:Report the normal consistency as the average
36、number ofmillilitres of water required to be added to 100 g of the drymixture to the nearest whole millilitre.8.5 Precision and BiasThe precision and bias of the testmethod for normal consistency of gypsum plaster have notbeen determined.9. Normal Consistency of Gypsum Concrete9.1 Significance and U
37、seThis test method is used todetermine the volume of water required for mixing gypsumconcrete when performing the setting time and compressivestrength tests.9.2 Apparatus:FIG. 2 ConsistometerC 472 99 (2004)39.2.1 Consistometer (Fig. 2)The consistometer consists ofa conical vessel made of noncorrodin
38、g, nonabsorbent material,and having an inside diameter of 9 in. (229 mm) at the top and134 in. (44.5 mm) at the bottom, and a height of 512 in. (139.7mm). It shall be provided with a sliding gate at the bottom andsupported so that the bottom is 4 in. (102 mm) above the baseplate. The base plate shal
39、l be of plate glass, free of scratchesand about 18 in. (457 mm) square.9.2.2 Balance, capable of weighing not less than 2000 g ata precision of 1 g.9.3 Procedure:9.3.1 Clean and dry the consistometer and the base plate andclose the sliding gate.9.3.2 Sift 2000 g of the sample into a known volume ofw
40、ater (see 5.1) to which 1.0 g of sodium citrate has previouslybeen added. After allowing the sample to soak for 1 min, stirthe mixture for 3 min to an even fluidity. Pour the mixture intothe consistometer until level with the top. Then rapidly andcompletely open the sliding gate, allowing the mixtur
41、e to runout onto the base plate. When the sliding gate is opened, takecare to avoid jarring the consistometer.9.3.3 Measure the resulting patty along its major and minoraxes and determine the average diameter.9.3.4 Test gypsum concrete with different amounts of wateruntil a patty diameter of 380 6 1
42、3 mm (15 612 in.) isobtained.9.4 ReportReport the normal consistency as the numberof millilitres of water to the nearest whole millilitre required tobe added to 100 g of the gypsum concrete.9.5 Precision and BiasThe precision and bias of the testmethod for normal consistency of gypsum concrete have
43、notbeen determined.10. Setting Time10.1 Significance and UseThis test method is used todetermine the setting time of gypsum plaster and gypsumconcrete, and is used to determine compliance with gypsumplaster and gypsum concrete specifications. Since variable jobconditions influence the setting time,
44、the degree of correlationbetween this test method and service performance has not beendetermined.10.1.1 This test method does not determine the time ofcomplete hydration of gypsum plaster or gypsum concrete. Todetermine the time of complete hydration see Setting Time,(Temperature Rise Method,) Secti
45、on 11.10.2 Apparatus:10.2.1 Vicat ApparatusThe Vicat apparatus (Fig. 3) shallconsist of a frame, A, bearing a movable rod, B, weighing 300g, one end, C, the plunger end, being 10 mm in diameter for adistance of not less than 50 mm, the other end having aremovable needle, D, 1 mm in diameter and 50 m
46、m in length.The rod, B, shall be reversible, shall be able to be held in anyposition by a screw, E, and shall have an adjustable indicator,F, that moves over a scale (graduated in millimetres) attachedto the frame, A. The paste shall be held in a rigid conical ring,G, resting on a glass plate, H, ab
47、out 100 mm square. The ringshall be made of a noncorroding, nonabsorbent material andshall have an inside diameter of 70 mm at the base and 60 mmat the top, and a height of 40 mm.FIG. 3 Vicat ApparatusC 472 99 (2004)410.2.2 In addition, the Vicat apparatus shall conform to thefollowing requirements:
48、Weight of plunger 300 6 0.5 gDiameter of larger end of plunger 10 6 0.05 mmDiameter of needle 1 6 0.05 mmInside diameter of ring at bottom 70 6 3mmInside diameter of ring at top 60 6 3mmHeight of ring 40 6 1mmGraduated scale The graduated scale, whencompared with a standardscale accurate to within 0
49、.1mm at all points, shall notshow a deviation at any pointgreater than 0.25 mm.NOTE 6Automatic setting time apparatus are commercially availableand may be used provided they can be shown to give the same results asthe specified apparatus and procedure.10.2.3 Balance, capable of weighing not less than 500 g ata precision of 0.1 g.10.2.4 Stopwatch or Clock, for determining setting time.10.2.5 Temperature and Humidity Controlled Cabinet, ca-pable of maintaining a temperature of 21 6 1C (70 6 2F)and a relative humidity of not less than 85
