ASTM D4373-02(2007)
(Test Method)Standard Test Method for Rapid Determination of Carbonate Content of Soils
Standard Test Method for Rapid Determination of Carbonate Content of Soils
SCOPE
1.1 This test method covers the determination of carbonate content of soils and soft rock which can be readily broken down by mechanical effort. It is a gasometric method that utilizes a simple portable apparatus. Results should be clearly stated as the calcite equivalent in percent because different carbonate species cover a wide range of percent calcite equivalent as shown below for a number of carbonates:
For example, a 100 % dolomite would be expected to yield 108.6 % calcite equivalent while 100 % siderite would yield only 86.4 % calcite equivalent. Calcite and aragonite reactions will typically complete within about 10 min. This method does not distinguish between the carbonate species and such determination must be made using quantitative chemical analysis methods such as atomic absorption.
1.2 The values stated in SI units are to be regarded as the standard.
1.3 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D 6026.
1.4 The method used to specify how data are collected, calculated, or recorded in this standard is not directly related to the accuracy to which the data can be applied in design or other uses, or both. How one applies the results obtained using this standard is beyond its scope.
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 specific precaution statements, see Section 8.
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Designation: D4373 − 02(Reapproved 2007)
Standard Test Method for Rapid Determination of
Carbonate Content of Soils
This standard is issued under the fixed designation D4373; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
1.1 This test method covers the determination of carbonate
bility of regulatory limitations prior to use. For specific
content of soils and soft rock which can be readily broken
precaution statements, see Section 8.
down by mechanical effort. It is a gasometric method that
utilizes a simple portable apparatus. Results should be clearly
2. Referenced Documents
stated as the calcite equivalent in percent because different
carbonate species cover a wide range of percent calcite
2.1 ASTM Standards:
equivalent as shown below for a number of carbonates:
C25 Test Methods for Chemical Analysis of Limestone,
Calcite Quicklime, and Hydrated Lime
Species Cation
Equivalent, %
D653 Terminology Relating to Soil, Rock, and Contained
Magnesite Mg 117.0
Fluids
Dolomite Ca, Mg 108.6
Calcite Ca 100.0 D3740 Practice for Minimum Requirements for Agencies
Aragonite Ca 100.0
Engaged in Testing and/or Inspection of Soil and Rock as
Rhodocrosite Mn 87.1
Used in Engineering Design and Construction
Siderite Fe 86.4
Smithsonite Zn 79.8
D4753 Guide for Evaluating, Selecting, and Specifying Bal-
Witherite Ba 50.7
ances and Standard Masses for Use in Soil, Rock, and
Cerrusite Pb 37.5
Construction Materials Testing
For example, a 100 % dolomite would be expected to yield
D6026 Practice for Using Significant Digits in Geotechnical
108.6 % calcite equivalent while 100 % siderite would yield
Data
only 86.4 % calcite equivalent. Calcite and aragonite reactions
E145 Specification for Gravity-Convection and Forced-
will typically complete within about 10 min.This method does
Ventilation Ovens
not distinguish between the carbonate species and such deter-
mination must be made using quantitative chemical analysis
3. Terminology
methods such as atomic absorption.
3.1 For definitions of terms used in this standard see
1.2 The values stated in SI units are to be regarded as the
Terminology D653.
standard.
1.3 All observed and calculated values shall conform to the
4. Summary of Test Method
guidelines for significant digits and rounding established in
4.1 The carbonate content (calcite equivalent) of soil is
Practice D6026.
determined by treating a 1-g dried soil specimen with hydro-
1.4 The method used to specify how data are collected,
chloric acid (HCl) in an enclosed reaction cylinder (reactor).
calculated, or recorded in this standard is not directly related to
Carbon dioxide (CO ) gas is evolved during the reaction
theaccuracytowhichthedatacanbeappliedindesignorother
between the acid and carbonate fraction of the specimen. The
uses, or both. How one applies the results obtained using this
resulting pressure generated in the closed reactor is propor-
standard is beyond its scope.
tional (see Fig. 1) to the calcite equivalent of the specimen.
1.5 This standard does not purport to address all of the
This pressure is measured with a suitable pressure gauge, or
safety concerns, if any, associated with its use. It is the
equivalent pressure-measuring device, that is pre-calibrated
with reagent grade calcium carbonate.
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
RockandisthedirectresponsibilityofSubcommitteeD18.06onPhysical-Chemical
Interactions of Soil and Rock. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2007. Published October 2007. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1984. Last previous edition approved in 2002 as D4373 – 02. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D4373-02R07. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4373 − 02 (2007)
FIG. 1 Typical Calibration Curve for 0.374L Test Cell and 70 kPa (10 psi) Pressure Gage
cautioned that compliance with Practice D3740 does not in itself assure
5. Significance and Use
reliable results. Reliable results depend on many factors; Practice D3740
5.1 This test method is used to determine the presence and
provides a means of evaluating some of those factors.
quantity of carbonate in a soil specimen in terms of the calcite
equivalent. The method is generally intended for use as an
6. Apparatus
index of approximate carbonate content to assist with charac-
6.1 Rapid Carbonate Analyzer—Aschematicdrawingofthe
terizing marine soils. Other test methods exist (such as Method
rapid carbonate analyzer is shown in Fig. 2. The basic
C25) to evaluate calcium carbonate equivalency for purposes
components of this apparatus include:
of characterizing use of calcareous materials as soil modifiers
6.1.1 Reaction Cylinder (Reactor) , with threaded cap and
or agricultural lining materials.
O-ring seal to enclose the cylinder. A clear plastic cylinder
5.1.1 Calcium carbonates (CaCO ) are known cementing
allows viewing of effervescent reaction.
agents, are water soluble at pH < 7, and are soft on the Mohs’
6.1.2 Pressure Gauge (Bourdon Tube-type or Electronic
scale compared to other soil minerals.
Pressure Transducer), 70 kPa (10 psi), with an accuracy of
5.2 This test method has limitations as follows:
0.25 %, and a readability of 0.5 kPa (0.1 psi).
5.2.1 If low carbonate contents (calcite equivalents) are
6.1.3 Acid Container, of clear plastic with a bail handle to
measured, the user does not know whether the soil is low in
hold 20 mL of acid. Optionally, in lieu of the acid container,
carbonate content or contains cerrusite, witherite, etc., which
use a soil container of clear plastic to hold1gof soil, with
are carbonate species whose reactions with hydrochloric acid
approximate dimensions of 25 mm diameter by 6 mm high
are either very slow or limited.
with a nominal 4 mm notch down the side of the soil container.
5.2.2 Testing times may be extensive (longer than 1 h) for
Acid added to dry soil often causes considerable splashing and
some carbonate species (such as dolomite) if calcite equiva-
use of soil container reduces splashing before reactor is sealed.
lents within about 1 % are required.
6.1.4 Pressure Relief Valve, for safe release of CO gas
5.2.3 The effects of specimen grain size, duration of testing,
pressure.
pH and specimen mass are discussed in the literature.
6.2 Balance—The balance must meet the requirements of
NOTE 1—The quality of the result produced by this standard is
Specification D4753 and this section. A Class GP1 balance
dependent on the competence of the personnel performing it, and the
with a minimum capacity of 100 g and a readability of 0.01 g
suitability of the equipment and facilities used. Agencies that meet the
is required to measure the soil mass.
criteria of Practice D3740 are generally considered capable of competent
and objective testing/sampling/inspection, etc. Users of this standard are
6.3 Drying Oven, thermostatically-controlled, preferably of
the forced-draft type, meeting the requirements of Specifica-
tionE145andcapableofmaintainingauniformtemperatureof
Demars, K.R., Chaney, R.C., Richter, J.A., “The Rapid Carbonate Analyzer,”
Geotechnical Testing Journal, ASTM, Vol. 6, No. 1, March 1981, pp. 30–34. 110 6 5°C
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