ASTM C471M-96

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Designation: C 471M – 96
METRIC
Standard Test Methods for
Chemical Analysis of Gypsum and Gypsum Products
[Metric]
This standard is issued under the fixed designation C 471M; 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.
1. Scope * C 842 Specification for Application of Interior Gypsum
Plaster
1.1 These test methods cover the chemical analysis of
D 1193 Specification for Reagent Water
gypsum and gypsum products, including gypsum ready-mixed
D 1428 Methods of Test for Sodium and Potassium in Water
plaster, gypsum wood-fibered plaster and gypsum concrete.
and Water-Formed Deposits by Flame Photometry
NOTE 1—Gypsum reference standard materials, prepared by Domtar, 4
D 2013 Method of Preparing Coal Samples for Analysis
Inc are available through Brammer Standards Company, Inc.
E 11 Specification for Wire-Cloth Sieves for Testing Pur-
1.2 The test methods appear in the following order:
poses
Sections
Alternative Procedure for Analysis for Calcium Sulfate by Ammonium 3. Terminology
Acetate Method 17-22
3.1 Definitions—Definitions shall be in accordance with
Alternative Procedure for Analysis for Sodium Chloride by the Coulo-
metric Method 23-29 Terminology C 11.
Complete Procedure 5-16
3.2 Definitions of Terms Specific to This Standard:
Determination of Sand in Set Plaster 30-36
3.2.1 sample as received, n—a representative portion of raw
Optional Procedure for Analysis for Sodium by Flame Photometry 47-54
Optional Procedure for Analysis for Sodium by the Atomic Absorp- gypsum or gypsum product in the state received by the testing
tion Method 40-46
laboratory, including aggregates, impurities and water content.
Preparation of Sample 4
3.2.2 dried sample, n—a sample dried of free water.
Wood-Fiber Content in Wood-Fiber Gypsum Plaster 37-39
3.2.3 riffle, n—a hand feed sample divider device that
1.3 The values stated in SI units are to be regarded as the
divides the sample into two parts of approximately the same
standard.
weight. (D 2013)
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Preparation of Sample
responsibility of the user of this standard to establish appro-
4.1 General Procedures—Details of sample preparation
priate safety and health practices and determine the applica-
will vary according to the type of material being tested.
bility of regulatory limitations prior to use.
4.1.1 Sample As Received—Use a sufficient amount of
sample such that, after sieving, not less than 50 g of sample
2. Referenced Documents
will remain for testing. Weigh the entire sample immediately
2.1 ASTM Standards:
after opening the container in which the material was received.
C 11 Terminology Relating to Gypsum and Related Gyp-
This will become the weight of the sample as received.
sum Building Materials and Systems
4.1.2 Drying—Dry the sample in accordance with Section
C 22/C 22M Specification for Gypsum
7. This will be the weight of the dried sample.
C 28 Specification for Gypsum Plasters
4.1.3 Crushing and Grinding—Crush and grind the sample
C 59 Specification for Gypsum Casting and Molding Plas-
by hand with a mortar and pestle or by mechanical crushing
ter
and grinding equipment to pass a 250-μm (No. 60) sieve. Take
C 61 Specification for Gypsum Keene’s Cement
care, particularly with mechanical equipment, not to expose the
C 317 Specification for Gypsum Concrete
sample to temperatures of more than 52°C. Clean the equip-
ment thoroughly between samples. Thoroughly remix the
ground sample and store it in an airtight container to avoid
These test methods are under the jurisdiction of ASTM Committee C-11 on
contamination.
Gypsum and Related Building Materials and Systems and are the direct responsi-
bility of Subcommittee C11.01 on Specifications and Test Methods for Gypsum
Products.
Current edition approved Nov. 10, 1996. Published January 1997. Originally Annual Book of ASTM Standards, Vol 11.01.
published as C 471 – 61. Last previous edition C 471 – 95. Annual Book of ASTM Standards, Vol 05.05.
2 5
Annual Book of ASTM Standards, Vol 04.01. Annual Book of ASTM Standards, Vol 14.02.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
C 471M
4.1.4 Rehydrating—Thoroughly blend and rehydrate 5.5 Calcining Oven or Furnace—Capable of achieving and
samples which contain calcium sulfate in forms other than maintaining temperatures to not less than 1000°C.
CaSO ·2H O and natural anhydrite. Place the sample in 5.6 Weighing Bottles—Borosilicate glass or ceramic con-
4 2
distilled water and keep it wet for not less than 48 h. Dry the tainers with lids that can be sealed tightly.
hydrated sample in an oven at 45 6 3°C to constant weight and 5.7 Hot Plate—A controllable hot plate capable of heating
recrush or grind it in accordance with 4.1.3. casseroles to approximately 120°C.
4.1.5 Sample Reduction—Thoroughly mix and reduce large 5.8 Porcelain Casseroles—With a capacity of 50 to 100 mL.
samples as required by quartering or by the use of a riffle to 5.9 Filtering Funnels.
obtain a specimen of approximately 50 g. 5.10 Filter Paper—Ashless filter paper Whatman #42 or
4.2 Gypsum (C 22/C 22M)—Gypsum samples will be re- equivalent.
ceived in the form of rocks, powder or both. If necessary 5.11 Porcelain Crucibles.
reduce and crush the entire dried sample in accordance with 5.12 Mortar and Pestle.
4.1.3 and 4.1.5. 5.13 Mechanical Jaw Crusher—Capable of crushing gyp-
4.3 Gypsum Plaster, (C 28). sum rocks up to 50 mm diameter.
4.3.1 Gypsum Ready-Mixed Plaster or Gypsum WoodFi- 5.14 Mechanical Grinder—Burr mill or equivalent capable
bered Plaster—Screen the dried sample through a 150-μm (No. of grinding the granular output of the jaw crusher specified in
100) sieve and discard the residue retained on the sieve. 5.13.
Reweigh the remaining sample and calculate the percentage of
6. Reagents
the dried sample. Reduce the sample in accordance with 4.1.5.
6.1 Purity of Reagents—Use reagent grade chemicals in all
Thoroughly blend and rehydrate the specimen in accordance
tests. Unless otherwise indicated, use reagents that conform to
with 4.1.4.
the specifications of the Committee on Analytical Reagents of
4.3.2 Gypsum Neat Plaster or Gypsum Gauging Plaster—
the American Chemical Society, where such specifications are
Reduce the dried sample in accordance with 4.1.5. Thoroughly
available. If it is necessary to use other grades first ascertain
blend and rehydrate the specimen in accordance with 4.1.4.
that the reagent is of sufficiently high purity to permit its use
4.4 Gypsum Casting and Molding Plaster, (C 59)—Reduce
without lessening the accuracy of the determination.
the dried sample in accordance with 4.1.5. Thoroughly blend
6.1.1 Ammonium Chloride (NH Cl).
and rehydrate the specimen in accordance with 4.1.4.
6.1.2 Ammonium Hydroxide (sp gr 0.90)—Concentrated
4.5 Gypsum Keene’s Cement, (C 61)—Reduce the dried
ammonium hydroxide (NH OH).
sample in accordance with 4.1.5. Blend in no more than 1 %
6.1.3 Ammonium Nitrate (25 g/L)—Dissolve 25 g of am-
molding plaster or K SO and rehydrate the specimen in
2 4
monium nitrate (NH NO ) in water and dilute to 1 L.
accordance with 4.1.4. 4 3
6.1.4 Ammonium Oxalate ((NH ) C O ).
4.6 Gypsum Concrete, (C 317)—Screen the dried sample
4 2 2 4
6.1.5 Barium Chloride (100 g/L)—Dissolve 100 g of
through a 150-μm (No. 100) sieve and discard the residue
barium chloride (BaCl ·2H O) in water and dilute to 1 L.
retained on the sieve. Reweigh the remaining sample and
2 2
6.1.6 Calcium Chloride (CaCl )—Anhydrous Calcium
calculate the percentage of the dried sample. Reduce the 2
Chloride with a combined water of not more than 5 %.
sample in accordance with 4.1.5. Thoroughly blend and rehy-
6.1.7 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
drate the specimen in accordance with 4.1.4.
chloric acid (HCl).
4.7 Gypsum Board—Cut or break the dried sample into
6.1.8 Hydrochloric Acid (1 + 4)—Mix 1 volume of HCl (sp
small pieces. Using a mortar and pestle, strike the pieces of the
gr 1.19) with 4 volumes of water.
sample to loosen the paper face. Remove the pieces of paper by
6.1.9 Hydrochloric Acid (1 + 5)—Mix 1 volume of HCl (sp
hand as they are separated from the core of the gypsum board.
gr 1.19) with 5 volumes of water.
Carefully scrape any remaining powder from the paper. When
6.1.10 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
all the paper has been removed from the pieces of the sample,
(HNO ).
reduce the sample in accordance with 4.1.5. Thoroughly blend
6.1.11 Potassium Chromate Solution (100 g/L)—Dissolve 5
and rehydrate the specimen in accordance with 4.1.4.
g of potassium chromate (K CrO ) in 50 mL of water, mix, add
2 4
COMPLETE PROCEDURE
10 drops of 0.05 N silver nitrate (AgNO ) solution, allow to
stand for 5 min, and filter.
5. Apparatus
6.1.12 Potassium Permanganate (5.6339 g/L)—Dissolve
5.1 Analytical Balance—Capable of weighing not less than
5.6339 g of potassium permanganate (KMnO ) in water and
1 g at a precision of 0.0001 g.
dilute to 1 L.
5.2 Balance—Capable of weighing not less than 100 g at a
precision of 0.001 g.
Whatman No. 42 or an equivalent filter paper has been found suitable for this
5.3 Drying Oven—A mechanical convection oven set at 45
purpose.
6 3°C.
Reagent Chemicals, American Chemical Society Specifications, American
5.4 Desiccator—Capable of being tightly sealed and con-
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
taining calcium chloride or equivalent desiccant.
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,
Detailed requirements for this sieve are given in Specification E 11. MD.
C 471M
6.1.13 Silver Nitrate, Standard Solution (0.05 N)—Prepare 8.3.2 Weigh out three specimens of approximately 1 g each
and standardize a 0.05 N silver nitrate (AgNO ) solution. of the sample as prepared in Section 4 and dried in Section 7
6.1.14 Sodium Ammonium Phosphate—(NaNH HPO ). to a precision of 0.0001 g in the previously tared weighing
4 4
6.1.15 Sulfuric Acid (sp gr 1.84)—Concentrated sulfuric bottles and record the total weight with lids.
acid (H SO ). 8.3.3 Place the specimens in the calcining oven with the lids
2 4
6.1.16 Sulfuric Acid (1 + 6)—Carefully mix 1 volume of placed loosely on each bottle or crucible for2hor until
H SO (sp gr 1.84) with 6 volumes of water. constant weight has been obtained.
2 4
6.1.17 Nitric Acid (0.1 N)—Mix 1.4 mL of HNO (sp gr 8.3.4 Place the lids tightly on the weighing bottles, remove
1.42) with 200 mL of water. from the oven, and place in the desiccator to cool to room
6.1.18 Phenolphthalein Indicator Solution—Dissolve 0.25 temperature.
g of phenolphthalein in 30 mL of methanol and dilute to 50 mL 8.3.5 Weigh each specimen to a precision of 0.0001 g and
with water. record the weights.
6.1.19 Sodium Hydroxide Solution (0.1 N)—Dissolve1gof 8.3.6 Retain the residues for carbon dioxide analysis.
sodium hydroxide (NaOH) in 250 mL of water. 8.4 Calculation and Report—Calculate and report the aver-
6.1.20 Water—Reagent water shall be in accordance with age loss in weight of the three specimens as a percentage of the
Specification D 1193, type II. Specification D 1193 gives the sample as received or of the dried sample, as required, to the
following values for type II grade water. nearest 0.001 g and record the tare weights.
8.5 Precision and Bias—Neither the precision nor the bias
Electrical conductivity, max, μS/cm at 298 K (25-C) 1.0
Electrical resistivity, min, MV·cm at 298 K (25-C) 1.0
for the combined water analysis has been determined.
Total organic carbon (TOC), max, μg/L 50.0
Sodium, max, μg/L 5.0
9. Carbon Dioxide
Chlorides max, μg/L 5.0
Total silica, max, μg/L 5.0
9.1 Summary of Test Method—The sample is decomposed
with HCl and the liberated CO is passed through a series of
7. Free Water scrubbers to remove water and sulfides. The CO is absorbed
with Ascarite, a special sodium hydroxide absorbent, and the
7.1 Significance and Use—The free water analysis deter-
gain in weight of the absorption tube is determined and
mines the amount of free water contained in the sample as
calculated as percent CO .
opposed to chemically combined water, and prepares the 2
9.2 Significance and Use—The carbon dioxide analysis is
sample for further analysis.
useful in estimating carbonates and organic carbon for chemi-
7.2 Procedure:
cal balance.
7.2.1 Weigh a sample of the material as received of not less
9.3 Special Reagents:
than 50 g to a precision of 0.001 g and spread it out in a thin
9.3.1 Magnesium Perchlorate Desiccant —for drying.
layer in a suitable vessel. Place in an oven and dry at 45 6 3°C
9.3.2 Sodium Hydroxide Absorbent —a coarse sodium hy-
for 2 h, then cool in a desiccator and weigh again. The loss of
droxide coated silica.
weight corresponds to the free water.
9.4 Special Apparatus—The apparatus illustrated in Fig. 1
7.2.2 Retain the sample in a sealed container or in the
consists of the following:
desiccator for further analysis.
9.4.1 Purifying Jar A, Fleming, containing sulfuric acid.
7.3 Calculation and Report—Calculate and report loss in
9.4.2 Drying Tube B, U-shaped with side arms and glass-
weight as a percentage of the sample as received or of the dried
stoppers. Side arms are shaped to hold rubber tubing. Contains
sample as required.
Anhydrone on left side and Ascarite on right side.
7.4 Precision and Bias—Neither the precision nor the bias
9.4.3 Erlenmeyer Flask C, 250 mL, 24/20 ground-glass
for the free water analysis has been determined.
joint.
8. Combined Water
9.4.4 Separatory Funnel D, with ground glass stopper and
8.1 Significance and Use—The combined water analysis
interchangeable hollow ground-glass joint. A delivery tube
determines the percent of chemically combined water and is bent at the end extends into the sample flask approximately 15
used to calculate the purity of gypsum or the amount of
mm from the bottom and is used to introduce acid into flask.
gypsum or gypsum plaster in gypsum products. 9.4.5 Condenser E.
8.2 Interferences—Some organic materials may partially
9.4.6 Gas-Washing Bottle F, 250 mL, with fritted disk
decompose and give high results. If hydrated compounds other co
...