ASTM C472-99(2004)
(Test Method)Standard Test Methods for Physical Testing of Gypsum, Gypsum Plasters and Gypsum Concrete
Standard Test Methods for Physical Testing of Gypsum, Gypsum Plasters and Gypsum Concrete
ABSTRACT
These test methods cover the physical testing of gypsum, gypsum plasters, and gypsum concrete. Test methods are detailed for the following: precautions for physical tests, reagents and materials, free water, fineness, normal consistency of gypsum plaster and gypsum concrete, setting time, setting time (temperature rise method), compressive strength, and density. Materials include distilled or deionized water and standard sand. For each test method, the following are specified: significance and use, apparatus, and procedure.
SCOPE
1.1 These test methods cover the physical testing of gypsum, gypsum plasters, and gypsum concrete.
1.2 The values regarded as the standard are either in inch-pound units or SI (metric). The values stated first shall be regarded as the standard. Values following in parentheses are approximate and are provided for information purposes only.
1.3 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) are not requirements of the standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For a specific precautionary statement, see X1.2.1.
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Standards Content (Sample)
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Designation: C 472 – 99 (Reapproved 2004)
Standard Test Methods for
Physical Testing of Gypsum, Gypsum Plasters and Gypsum
Concrete
This standard is issued under the fixed designation C 472; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses 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 C11 Terminology Relating to Gypsum and Related Build-
ing Materials and Systems
1.1 These test methods cover the physical testing of gyp-
C 778 Specification for Standard Sand
sum, gypsum plasters, and gypsum concrete.
E11 Specification for Wire Cloth and Sieve for Testing
1.2 The test methods appear in the following sections:
Purposes
Sections
3. Terminology
Precautions for Physical Tests 4
Reagents and Materials 5
3.1 Definitions:
Free Water 6
3.1.1 For useful definitions refer to TerminologyC11.
Fineness 7
Normal Consistency of Gypsum Plaster 8
Normal Consistency of Gypsum Concrete 9
4. Precautions for Physical Tests
Setting Time 10
4.1 Gypsum products are greatly affected by small amounts
Setting Time (Temperature Rise Method) 11
Compressive Strength 12
of impurities introduced by careless laboratory manipulation.
Density 13
In order to obtain accurate results, it is absolutely essential to
1.3 The values regarded as the standard are either in observe the following precautions:
inch-pound units or SI (metric). The values stated first shall be 4.1.1 Keep all apparatus thoroughly clean. Remove all
regarded as the standard. Values following in parentheses are traces of set plaster.
approximate and are provided for information purposes only.
NOTE 1—For mixing pastes and mortars, a 500-ml rubber dental bowl
1.4 The text of this standard references notes and footnotes
is a convenience.
which provide explanatory material. These notes and footnotes
NOTE 2—Use care when drying gypsum, gypsum plasters, or gypsum
(excluding those in tables and figures) are not requirements of concrete. Exceeding the specified drying temperatures may calcine the
specimens, which will cause inaccurate test results.
the standard.
1.5 This standard does not purport to address all of the
5. Reagents and Materials
safety concerns, if any, associated with its use. It is the
5.1 Distilled or Deionized Water—free of chlorides and
responsibility of the user of this standard to establish appro-
sulfates at a temperature of 21 6 1°C (70 6 2°F).
priate safety and health practices and determine the applica-
5.2 Standard Sand— Specification C 778, 20–30 sand.
bility of regulatory limitations prior to use. For a specific
precautionary statement, see X1.2.1.
6. Free Water
2. Referenced Documents
6.1 Significance and Use—This test method determines the
free water contained in gypsum, gypsum plasters, and gypsum
2.1 ASTM Standards:
concrete samples, and prepares the sample for subsequent
testing.
These test methods are under the jurisdiction of ASTM Committee C11 on
6.2 Apparatus:
Gypsum and Related Building Materials and Systems and are the direct responsi-
6.2.1 Balance, capable of weighing not less than 500 g at
bility of Subcommittee C11.01 on Specifications and Test Methods for Gypsum
a precision of 0.1 g.
Products.
Current edition approved May 1, 2004. Published June 2004. Originally
6.2.2 Drying Oven, set at 45 6 3°C.
approved in 1961. Last previous edition approved in 1999 as C 472–98.
6.2.3 Desiccator, containing calcium chloride or equiva-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
lent desiccant.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on 6.3 Procedure:
the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 472 – 99 (2004)
6.3.1 Weigh a sample of not less than 500 g of the material
as received to the nearest 0.1 g and spread it to a thin layer in
a suitable-vessel. Place in an oven (6.2.2) and dry for 2 h; then
cool in a desiccator (6.2.3) and weigh again.
6.3.2 Retain the dried sample in an airtight container until
used for the fineness test (Section 7).
6.4 Report—Reportthelossinweightasapercentageofthe
original weight of the sample as received to a precision of
0.1%.
6.5 Precision and Bias—The precision and bias of the free
water test method have not been determined.
7. Fineness
7.1 Significance and Use—This test method covers a pro-
cedure for determining the fineness of gypsum and gypsum
plasters and is used to determine compliance with gypsum and
gypsum plaster specifications. The degree of correlation be-
tween the results of this test method and service performance
has not been determined.
7.2 Apparatus:
7.2.1 Sieves, as required by a particular gypsum or gypsum
plaster specification, in accordance with SpecificationE11.
7.2.2 Balance, capable of weighing not less than 1000 g at
a precision of 0.1 g.
7.2.3 Mechanical Sieving Machine
7.3 Procedure:
A—Hinged support bracket D—Graduation mark
7.3.1 Determine fineness by sieving a known weight of the
B—Plunger support rod E—Lock screw
dried sample through sieves of the specified sizes (Note 3 and
C—Conical plunger F—Modified scale
Note 4). The size of the sample to be used in determining
G—Weight
fineness depends upon the particle size of the material. If the
FIG. 1 Modified Vicat Apparatus (Conical Plunger Method)
material will pass a 6.3-mm ( ⁄4-in.) sieve, a 100-g sample will
besufficient;ifthelargestparticlesaremorethan25mm(1in.)
8. Normal Consistency of Gypsum Plaster
in diameter, use not less than a 1000-g sample. With these
limitations the size of sample to be used is left to the discretion 8.1 Significance and Use—This test method is used to
of the operator. Shake the sample through each sieve with as determine the volume of water required for mixing gypsum
little abrasion as possible (Note 5). Weigh the amount of plaster when performing the setting time and compressive
material retained on each sieve and calculate the fineness, strength tests.
expressed as a percentage of the weight of the original sample. 8.2 Apparatus:
7.3.2 If a mechanical sieving machine is used, make a series 8.2.1 Modified Vicat Apparatus—The modified Vicat appa-
of tests at one minute intervals, with each type of material and ratus (Fig. 1) shall consist of a bracket, A, bearing a movable
sieve size combination to be used. When not more than 0.5 g brassrod,B,6.3mmindiameterandofsuitablelengthtofitthe
passes each sieve in a one minute interval, use that time as the Vicat Bracket. A conical plunger made of aluminum with an
standard sieving time for that test procedure on that machine. apex angle of 53° 08 min and a height of 45 mm shall be
attached to the lower end of the rod.The total weight of the rod
NOTE 3—For suggested method of sieving gypsum through a 45-µm
andplungershallbe35g.Ameansshallbeprovidedforadding
(No. 325) sieve, see Appendix X1.
a weight, G, to the rod, increasing the total weight to 50 g. The
NOTE 4—The sizes of the sieves to be used are given in the specifica-
rod shall be capable of being held in any position by a screw,
tions of ASTM covering the particular product in question.
NOTE 5—When sieving by hand through a 150-µm (No. 100) sieve, use E. The rod shall have a mark, D, midway between the ends
a lateral motion, and tap the side of the sieve with the palm of the hand.
which moves under a scale, F, graduated in millimetres,
Continuewithoutbrushinguntilnotmorethan0.5gpassesthroughduring
attached to the bracket, A.
1 min of sieving. If the sieve openings become clogged, transfer the
8.2.2 Mold—The conical ring mold shall be made of a
retained material temporarily to another vessel, invert the sieve over a
noncorroding, nonabsorbent material, and shall have an inside
sheet of paper on the table and tap it sharply against the table. Then
diameter of 60 mm at the base and 70 mm at the top and a
transfer all the retained material back into the sieve and continue sieving.
height of 40 mm.
7.4 Report—Report the percent by weight retained on each
sieve or passing particular sieves in accordance with the
material specification to the nearest full percentage point.
This method is described by Kuntze, R. A., “An Improved Method for the
7.5 Precision and Bias—The precision and bias of the
Normal Consistency of Gypsum Plasters,” ASTM Bulletin No. 246, ASTM, May
fineness test method have not been determined. 1960, p. 35.
C 472 – 99 (2004)
8.2.3 Base Plate—The base plate for supporting the ring 8.3.3 Test gypsum molding plaster and gypsum gauging
mold shall be of plate glass and about 100 mm square. plasterwithdifferentamountsofwateruntilapenetrationof30
6 2 mm is obtained. Use the rod and plunger for this
8.2.4 Balance, capable of weighing not less than 500 g at a
determination weighing 35 g.
precision of 0.1 g.
8.3.4 Test all gypsum mixtures containing aggregates with
8.2.5 Graduated Cylinder, shall be made to deliver the
different amounts of water until a penetration of 20 62mmis
indicated volume at 20°C (68°F) and shall be subdivided to not
obtained. Add weight to the rod and plunger to bring the total
less than 1 mL.
weight to 50 g for these determinations.
8.3 Procedure:
8.3.5 Mix gypsum neat plaster with standard sand (see 5.2)
8.3.1 Clean the plunger, mold, and base plate of the modi-
in the ratio of 200 g of sand to 100 g of plaster before testing
fied Vicat apparatus. Apply a thin coat of petroleum jelly or
for normal consistency.
other suitable lubricant to the upper surface of the base plate in
8.4 Report:
order to prevent leaks during the test.
Report the normal consistency as the average number of
8.3.2 Sift a weighed quantity of the sample (200 to 300 g as
millilitres of water required to be added to 100 g of the dry
required to fill the mold) into a known volume of water (See
mixture to the nearest whole millilitre.
5.1). If the plaster is unretarded, add to the mixing water 0.2 g
8.5 Precision and Bias—The precision and bias of the test
of sodium citrate per 100 g of sample. After allowing the
method for normal consistency of gypsum plaster have not
sample to soak for 2 min, stir the mixture for 1 min to an even
been determined.
fluidity. Pour this sample into the ring mold, work slightly to
remove air bubbles, and then strike off flush with the top of the
9. Normal Consistency of Gypsum Concrete
mold. Wet the plunger of the modified Vicat apparatus and
lowerittothesurfaceofthesampleatapproximatelythecenter 9.1 Significance and Use—This test method is used to
of the mold. Read the scale and release the plunger immedi- determine the volume of water required for mixing gypsum
ately.After the rod has settled, read the scale again. Make three concrete when performing the setting time and compressive
determinations on each mix, care being taken to have the mold strength tests.
completely filled and the plunger clean and wet. 9.2 Apparatus:
FIG. 2 Consistometer
C 472 – 99 (2004)
9.2.1 Consistometer(Fig.2)—Theconsistometerconsistsof 9.5 Precision and Bias—The precision and bias of the test
a conical vessel made of noncorroding, nonabsorbent material, method for normal consistency of gypsum concrete have not
and having an inside diameter of 9 in. (229 mm) at the top and been determined.
3 1
1 ⁄4 in. (44.5 mm) at the bottom, and a height of 5 ⁄2 in. (139.7
10. Setting Time
mm). It shall be provided with a sliding gate at the bottom and
supported so that the bottom is 4 in. (102 mm) above the base 10.1 Significance and Use—This test method is used to
plate. The base plate shall be of plate glass, free of scratches determine the setting time of gypsum plaster and gypsum
and about 18 in. (457 mm) square. concrete, and is used to determine compliance with gypsum
plaster and gypsum concrete specifications. Since variable job
9.2.2 Balance, capable of weighing not less than 2000 g at
conditions influence the setting time, the degree of correlation
a precision of 1 g.
between this test method and service performance has not been
9.3 Procedure:
determined.
9.3.1 Cleananddrytheconsistometerandthebaseplateand
10.1.1 This test method does not determine the time of
close the sliding gate.
complete hydration of gypsum plaster or gypsum concrete. To
9.3.2 Sift 2000 g of the sample into a known volume of
determine the time of complete hydration see Setting Time,
water (see 5.1) to which 1.0 g of sodium citrate has previously
(Temperature Rise Method,) Section 11.
been added. After allowing the sample to soak for 1 min, stir
10.2 Apparatus:
the mixture for 3 min to an even fluidity. Pour the mixture into
10.2.1 Vicat Apparatus—The Vicat apparatus (Fig. 3) shall
the consistometer until level with the top. Then rapidly and
consist of a frame, A, bearing a movable rod, B, weighing 300
completely open the sliding gate, allowing the mixture to run
g, one end, C, the plunger end, being 10 mm in diameter for a
out onto the base plate. When the sliding gate is opened, take
distance of not less than 50 mm, the other end having a
care to avoid jarring the consistometer.
removable needle, D, 1 mm in diameter and 50 mm in length.
9.3.3 Measure the resulting patty along its major and minor
The rod, B, shall be reversible, shall be able to be held in any
axes and determine the average diameter.
position by a screw, E, and shall have an adjustable indicator,
9.3.4 Test gypsum concrete with different amounts of water
F, that moves over a scale (graduated in millimetres) attached
until a patty diameter of 380 6 13 mm (15 6 ⁄2 in.) is
to the frame, A. The paste shall be held in a rigid conical ring,
obtained.
G, resting on a glass plate, H, about 100 mm square. The ring
9.4 Report—Report the normal consistency as the number shall be made of a noncorroding, nonabsorbent material and
of millilitres of water to the nearest whole millilitre required to shall have an inside diameter of 70 mm at the base and 60 mm
be added to 100 g of the gypsum concrete. at the top, and a height of 40 mm.
FIG. 3 Vicat Apparatus
C 472 – 99 (2004)
10.2.2 In addition, the Vicat apparatus shall conform to the
Bond plaster 1 ⁄2h1h
Gauging plaster:
following requirements:
Slow set 40 min 2 h
Weight of plunger 300 6 0.5 g
Quick set 15 min 5 min
Diameter of larger end of plunger 10 6 0.05 mm
Diameter of needle 1 6 0.05 mm
10.4 Report—Report the setting time as the elapsed time in
Inside di
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