ASTM C775-79(1997)e1
(Test Method)Standard Method for Particle-Size Analysis of Whiteware Clays (Withdrawn 2002)
Standard Method for Particle-Size Analysis of Whiteware Clays (Withdrawn 2002)
SCOPE
1.1 This method covers the quantitative determination of the distribution of particle sizes in kaolins and ball clays in the size range 44 to 0.1 [mu]m by the sedimentation process. Particles are allowed to settle under normal gravitational forces and concentrations of particles in the size range 44 to 2 [mu]m are measured using a hydrometer. Centrifuging is used to cause the smaller particles to settle more rapidly so that concentrations of particles in the size range 2 to 0.1 [mu]m may be measured using a pipet.
1.2 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.
General Information
Standards Content (Sample)
e1
Designation: C 775 – 79 (Reapproved 1997)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Method for
Particle-Size Analysis of Whiteware Clays
This standard is issued under the fixed designation C 775; 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.
e NOTE— Section 16 was added editorially in October 1997.
1. Scope Fig. 2 shall be provided to hold the sample while it is being
dispersed.
1.1 This method covers the quantitative determination of the
distribution of particle sizes in kaolins and ball clays in the size
NOTE 1—A few clays are difficult to disperse and for these clays the use
range 44 to 0.1 μm by the sedimentation process. Particles are of a Waring blender or equivalent is recommended.
allowed to settle under normal gravitational forces and con-
4.2 Centrifuge—The centrifuge shall have bottles with a
centrations of particles in the size range 44 to 2 μm are
capacity of approximately 250 mL, and the rotational speed
measured using a hydrometer. Centrifuging is used to cause the
shall be closely controlled and measured using a tachometer. A
smaller particles to settle more rapidly so that concentrations of
timing device should be used to stop the centrifuge after
particles in the size range 2 to 0.1 μm may be measured using
predetermined time intervals.
a pipet.
4.3 Hydrometer—An ASTM hydrometer, graduated to read
1.2 This standard does not purport to address all of the
in either specific gravity of the suspension or grams per litre of
safety concerns, if any, associated with its use. It is the
suspension, and conforming to the requirements for Hydrom-
responsibility of the user of this standard to establish appro-
eter 152H in Specification E 100.
priate safety and health practices and determine the applica-
4.4 Sedimentation Cylinder—A glass cylinder essentially 18
bility of regulatory limitations prior to use.
in. (457 mm) in height and 2 ⁄2 in. (63.5 mm) in diameter, and
marked for a volume of 1000 mL. The inside diameter shall be
2. Referenced Documents
such that the 1000-mL mark is 360 6 20 mm from the bottom
2.1 ASTM Standards:
on the inside.
E 11 Specification for Wire-Cloth Sieves for Testing Pur-
4.5 Sieve—A No. 325 (45-μm) sieve conforming to the
poses
requirements of Specification E 11.
E 100 Specification for ASTM Hydrometers
4.6 Water Bath or Constant-Temperature Room—A water
bath or constant-temperature room for maintaining the clay
3. Terminology Definition
suspension at a constant temperature during the hydrometer
3.1 equivalent spherical diameter—the diameter of a
analysis. A satisfactory water tank is an insulated tank that
spherical particle having the same density and sedimentation
maintains the temperature of the suspensions at a convenient
rate in the same fluid as the clay particles being tested.
constant temperature at or near 25°C (77°F). Such a device is
illustrated in Fig. 3. In cases where the work is performed in a
4. Apparatus
room at an automatically controlled temperature, the water
4.1 Stirring Apparatus—A mechanically operated stirring
bath is not necessary.
device in which a suitably mounted electric motor turns a
vertical shaft at a speed of not less than 10 000 r/min without
5. Records
load. The shaft shall be equipped with a replaceable stirring
5.1 Dispersing Agent—Dissolve2gof sodium hexameta-
paddle made of metal, plastic, or hard rubber as shown in Fig.
phosphate (sometimes called sodium metaphosphate (NaPO ))
1. The shaft shall be of such length that the stirring paddle will
in 1 L of distilled or demineralized water.
3 1
operate at not less than ⁄4 in. (19.0 mm) nor more than 1 ⁄2 in.
NOTE 2—Some fine-grained clays require more of the dispersant and up
(38.1 mm) above the bottom of the dispersion cup. A special
to 6 g/L of water may be added after trials have been run to determine the
dispersion cup conforming to either of the designs shown in
percentage of dispersant causing the maximum fluidity using a viscometer
suitable for clay-water suspensions.
This method is under the jurisdiction of ASTM Committee C-21 on Ceramic
NOTE 3—Solutions of this salt, if acidic, slowly revert or hydrolyze
Whitewares and Related Products and is the direct responsibility of Subcommittee
back to the orthophosphate form with a resultant decrease in dispersive
C21.04 on Clays.
Current edition approved Aug. 31, 1979. Published November 1979. Originally
published as C 775 – 74. Last previous edition C 775 – 74.
2 4
Annual Book of ASTM Standards, Vol 14.02. Available from Waring Products Div., Dynamics Corp. of America, New
Annual Book of ASTM Standards, Vol 14.03. Hartford, CT 06057.
C 775
Metric Equivalents
1 3
in. 0.001 0.049 ⁄2 ⁄4
(mm) (0.03) (1.24) (12.7) (19.0)
FIG. 1 Detail of Stirring Paddles
Metric Equivalents
in. 1.3 2.6 3.75
(mm) (33) (66) (95.2)
FIG. 2 Dispersion Cups of Apparatus
action. Solutions should be prepared frequently (at least once a month) or
adjusted to pH of 8 or 9 by means of sodium carbonate. Bottles containing
solutions should have the date of preparation marked on them.
5.2 Water—All water used shall be either distilled or
demineralized water. The water for a hydrometer test shall be
brought to the temperature that is expected to prevail during the
hydrometer test. For example, if the sedimentation cylinder is
to be placed in the water bath, the distilled or demineralized
water to be used shall be brought to the temperature of the
controlled water bath; or, if the sedimentation cylinder is used
in a room with controlled temperature, the water for the test
shall be at the temperature of the room. The basic temperature
for the hydrometer test is 25°C (77°F). Small variations of
temperature do not introduce differences that are of practical
significance and do not prevent the use of corrections derived
FIG. 3 Insulated Water Bath
as prescribed.
C 775
TABLE 1 Values of Effective Depth Based on Hydrometer and NOTE 4—The amount of the inaccuracy increases as the variation from
A
Sedimentation Cylinder of Specified Sizes
the standard temperature increases.
Hydrometer 152H
TABLE 2 Values of K for Use in Equation for Computing
Actual Actual
Effective Effective
Diameter of Particles Having a Specific Gravity of 2.60 in
Hydrometer Hydrometer
Depth, L,cm Depth, L,cm
Hydrometer Analysis
Reading Reading
Temperature, °C K Values
0 16.3 31 11.2
1 16.1 32 11.1
16 0.01457
2 16.0 33 10.9
17 0.01439
3 15.8 34 10.7
18 0.01421
4 15.6 35 10.6
19 0.01403
5 15.5
20 0.01386
21 0.01369
6 15.3 36 10.4
22 0.01353
7 15.2 37 10.2
23 0.01337
8 15.0 38 10.1
24 0.01321
9 14.8 39 9.9
25 0.01306
10 14.7 40 9.7
26 0.01291
27 0.01277
11 14.5 41 9.6
28 0.01264
12 14.3 42 9.4
29 0.01249
13 14.2 43 9.2
30 0.01236
14 14.0 44 9.1
15 13.8 45 8.9
6.1.3 Hydrometers are graduated by the manufacturer to be
16 13.7 46 8.8
read at the bottom of the meniscus formed by the liquid on the
17 13.5 47 8.6
18 13.3 48 8.4
stem. Since it is not possible to secure readings of the clay
19 13.2 49 8.3
suspensions at the bottom of the meniscus, readings must be
20 13.0 50 8.1
taken at the top and a correction factor applied.
21 12.9 51 7.9 6.1.4 The net amount of the corrections for the three items
22 12.7 52 7.8
enumerated is designated as the composite correction, and may
23 12.5 53 7.6
be determined experimentally.
24 12.4 54 7.4
25 12.2 55 7.3
6.2 For convenience, a graph or table of composite correc-
tions for a series of 1° temperature differences for the range of
26 12.0 56 7.1
expected test temperatures may be prepared and used as
27 11.9 57 7.0
28 11.7 58 6.8
needed. Measurement of the composite corrections may be
29 11.5 59 6.6
made at two temperatures spanning the range of expected test
30 11.4 60 6.5
temperature, and corrections for the intermediate temperatures
A
Values of effective depth are calculated from the equation:
calculated assuming a straight-line relationship between the
L 5 L + ⁄2[L −(V /A)]
1 2 B
where: two observed values.
L 5 effective depth, cm,
6.3 Prepare 1000 mL of liquid composed of distilled or
L 5 distance along the stem of the hydrometer from the top of the bulb to the
demineralized water and the dispersing agent in the same
mark for a hydrometer reading, cm,
L 5 overall length of the hydrometer bulb, cm, proportion as will prevail in the sedimentation (hydrometer)
V 5 volume of hydrometer bulb, cm , and
B
test. Place the liquid in the sedimentation cylinder and the
A 5 cross-sectional area of sedimentation cylinder, cm
cylinder in the constant-temperature water bath, set for one of
Values used in calculating the values in Table 1 are as follows:
For hydrometer 152H:
the two temperatures to be used. When the temperature of the
L 5 10.5 cm for a reading of 0 g/L
liquid becomes constant, insert the hydrometer, and, after a
5 2.3 cm for a reading of 50 g/L
short interval to permit the hydrometer to come to the
L 5 14.0 cm
V 5 67.0 cm
B temperature of the liquid, read the hydrometer at the top of the
A 5 27.8 cm
meniscus formed on the stem. For Hydrometer 152H, it is the
difference between the reading and zero. Bring the liquid and
the hydrometer to the other temperature to be used, and secure
6. Hydrometer Test and Sieve Analysis
the composite correction as before.
6.1 Determination of Composite Correction for Hydrometer
Reading: 7. Hygroscopic Moisture
6.1.1 Equations for percentages of clay remaining in sus-
7.1 When the sample is weighed for the hydrometer test,
pension, as given in Section 13, are based on the use of distilled
weigh out an auxiliary portion from 10 to 15 g in a small metal
or demineralized water. A dispersing agent is used in the water,
or glass container, dry the sample to a constant weight in an
however, and the specific gravity of the resulting liquid is
oven at 110 6 5°C (2306 9°F), and weigh again. Record the
appreciably greater than that of distilled or demineralized
weights.
water.
8. Dispersion of Clay
6.1.2 Calibrate the hydrometer at 20°C (68°F). Variations in
temperature from this standard temperature produce inaccura- 8.1 Weigh out a sample of 50 g of air-dry clay. Place the
cies in the actual hydrometer readings. sample in a 500-mL beaker and cover with 250 mL of the
C 775
dispersing agent (2 g/L). Stir until the clay is thoroughly sample further using the stirring device and pass through a No.
wetted. Allow to soak for at least 24 h. 325 (45-μm) sieve as described in Section 9. Transfer the
8.2 At the end of the soaking period disperse the sample suspension passing through the No. 325 sieve to a glass
further, using the stirring device. Transfer the clay-water slurry 1000-mL graduate and then dilute with distilled or demineral-
from the beaker into the special dispersion cup shown in Fig. ized water to within ⁄2 in. (12.7 mm) of the 1000-mL
2, washing any residue from the beaker into the special graduation mark. Place the suspension in the graduate in the
dispersion cup using distilled or demineralized water. Add constant-temperature water bath maintained at a temperature of
more of the distilled or demineralized water, if necessary, so 25°C (77°F). When the suspension reaches the temperature of
that the cup is more than half full. Stir for a period of 10 min. the bath fill the graduate to the 1000-mL graduation using
distilled or demineralized water.
9. Sieve Analysis
11.2 The centrifuge bottles used in this portion of the test
are illustrated in Fig. 4. Place a mark on the side of each bottle
9.1 Transfer the suspension to a No. 325 (45-μm) sieve,
at a level that represents a condition of the bottle filled with 250
collecting the suspension passing through the sieve for use in
mL of the clay-water suspension. This may be accomplished by
the hydrometer test. Rinse the special dispersion cup with a
using a 250-mL volumetric flask filled with water to add to
small amount of distilled or demineralized water and pour
each to the centrifuge bottles for marking of the desired level.
through the sieve. Transfer the material on the No. 325 sieve to
11.3 Using the palm of the hand over the open end of the
a suitable container, dry in an oven at 110 6 5°C (230 6 9°F)
graduate (or a rubber stopper in the open end), turn the cylinder
and weigh. Record the weight.
upside down and back for a period of 1 min as described in
10. Hydrometer Test 10.2. Fill one of the centrifuge bottles to the 250-mL calibra-
tion mark placed there previously.
10.1 Immediately after dispersion and passing through a
11.4 Centrifuge the suspension in the bottle for 24.45 min at
No. 325 (45-μm) sieve, transfer the clay-water slurry to the
a corrected centrifuge speed of 500 r/min. Measure the
glass sedimentation cylinder, and add distilled or demineral-
temperature of the suspension after centrifuging and record the
ized water until the total volume is 1000 mL.
average temperature of the suspension during centrifuging.
10.2 Using the palm of the hand over the open end of the
Place the end of the pipet 75 mm below the surface of the
cylinder (or a rubber stopper in the open end), turn the cylinder
clay-water suspension as shown in Fig. 4 and withdraw a 5-mL
upside down and back for a period of 1 min to complete the
specimen. Place the specimen in a tared weighing dish and
agitation of the slurry (Note 5). At the end of 1 min set the
evaporate to dryness at a temperature of 110 6 5°C (230 6
cylinder in a convenient location and take hydrometer readings
9°F) and weigh to determine the concentration of the clay in
at the following intervals of time (measured from the beginning
the suspension after centrifuging in grams per cubic centime-
of sedimentation), or as many as may be needed, depending on
tre.
the sample or the specification for the material under test; 2, 5,
11.5 Prepare three additional specimens of the clay-water
15, 30, 60, 240, and 360 min. If the controlled water bath is
suspension in the same manner as described in 11.3 and
used, the sedimentation cylinder should be placed in the bath
centrifuge at a speed of either 1000, 2000, or 2500 r/min for a
between the 2 and 5-min readings.
period of either 23.50, 36.70, or 93.90 min, respectively. After
NOTE 5—The number of turns during this minute should be approxi-
each centrifuging, take specimens at a depth of 75 mm below
mately 60, counting the turn upside down and back as two turns. Any clay
the surface of the suspension, dry and weigh as described in
remaining in the bottom of the cylinder during the first few turns should
11.4 to determine the concentration o
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