1、Designation: D4972 13D4972 18Standard Test MethodMethods forpH of Soils1This standard is issued under the fixed designation D4972; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses i
2、ndicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 ThisThese test method coversmethods cover the measurement of the pH of soils for uses other than for corrosion testing.that will pass the 2.00 mm (No. 10) si
3、eve. Such measurements are used in the agricultural, environmental, geotechnical, and naturalresources fields. This measurement determines the degree of acidity or alkalinity in soil materials suspended in water and a 0.01M calcium chloride solution. Measurements in both liquids are necessary to ful
4、ly define the soils pH. This variable is useful indetermining the solubility of soil minerals and the mobility of ions in the soil and assessing the viability of the soil-plantenvironment. A more detailed discussion of the usefulness of this parameter is not warranted here; however, it can be found
5、inmany discussions of the subject. A few such discussions are given asgiven in Refs (1-6)2 at the end of the text1.2 Two methods for measuring the pH of soils are provided. The method to be used shall be specified by the requestingauthority. When no method is specified, MethodAshall be used. The pH
6、is determined in test water and a calcium chloride solutionfor both methods.1.2.1 Method AThe pH is measured using a potentiometer having a pH sensitive electrode system. This method can be usedfor any application and must be used when the application warrants a higher level of resolution.1.2.2 Meth
7、od BThe pH is measured using pH sensitive paper. This method can be used for any application, however, becausepaper typically has a lower resolution, it provides an approximate estimate of the pH of the soil and should not be used when theapplication requires a higher level of resolution (Note 1).NO
8、TE 1For example, paper with a sensitivity to the nearest 1 pH unit placed into a buffer solution of 4 should indicate a pH of 4, however, it wouldnot indicate if the pH is 4.449 or 3.449.1.3 UnitsThe values stated in SI units are to be regarded as standard. No other units of measurement are included
9、 in thisstandard.1.4 All measured and calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026.1.4.1 The procedures used to specify how data are collected/recorded and calculated in the standard are regarded as the industrystandard. In additi
10、on, they are representative of the significant digits that generally should be retained. The procedures used do notconsider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the users objectives;and it is common practice to increase or reduce sign
11、ificant digits of reported data to be commensurate with these considerations.It is beyond the scope of these test methods to consider significant digits used in analysis methods for engineering data.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its
12、 use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.6 This international standard was developed in accordance with internationally recogniz
13、ed principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3C670 Practice for Preparin
14、g Precision and Bias Statements for Test Methods for Construction Materials1 ThisThese test method ismethods are under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.22 on Soilas a Medium Media for Plant Growth.Current edition approved No
15、v. 1, 2013July 1, 2018. Published November 2013July 2018. Originally approved in 1989. Last previous edition approved in 20072013 asD4972 01 (2007).D4972 13. DOI: 10.1520/D4972-13.10.1520/D4972-18.2 The boldface numbers in parentheses refer to a list of references at the end of this standard.3 For r
16、eferencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provid
17、e the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the st
18、andard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D653 Terminology Relating to Soil, Rock, and Contai
19、ned FluidsD1193 Specification for Reagent WaterD2487 Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System)D2488 Practice for Description and Identification of Soils (Visual-Manual Procedures)D3740 Practice for Minimum Requirements for Agencies Engaged in
20、Testing and/or Inspection of Soil and Rock as Used inEngineering Design and ConstructionD4220/D4220M Practices for Preserving and Transporting Soil SamplesD4753 Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and ConstructionMaterials TestingD6026
21、Practice for Using Significant Digits in Geotechnical DataD6913 Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve AnalysisG51 Test Method for Measuring pH of Soil for Use in Corrosion Testing3. Terminology3.1 Definitions:3.1.1 For common definitions of common technical ter
22、ms used in this standard, refer to Terminology D653.4. Summary of Test Method4.1 Measurement of This test method is used to determine the pH of soils in both suspensions of water and a calcium chloridesolution are made with either a potentiometer using a pH sensitive electrode system (Method A), or
23、pH sensitive paper (MethodB). The potentiometer is calibrated with buffer solutions of known pH. The pH sensitive paper is a less accurate measurement andshould only be used for a rough estimate of the soil pH. The electrode must be used for this measurement unless the pH sensitivepaper is specified
24、.a soil. Two similar test specimens are obtained from a representative sample that has been air-dried and screenedover a 2.00 mm (No. 10) sieve. From the material passing the 2.00 mm (No. 10) sieve, one specimen is mixed with test water andone is mixed with a calcium chloride solution. They are then
25、 thoroughly stirred and both are allowed to stand for one hour priorto testing using Method A or B.NOTE 1The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of theequipment and facilities used. Agencies that meet the
26、criteria of Practice D3740 are generally considered capable of competent and objectivetesting/sampling/inspection and the like. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results.Reliable results depend on many factors; Practice D3740
27、provides a means of evaluating some of those factors.5. Significance and Use5.1 The pH of the soil is a useful variable in determining the solubility of soil minerals and minerals, the mobility of ions inthe soil, and assessing the viability of the soil-plant environment.5.2 pH measurements are made
28、 in both test water and a calcium chloride solution because the calcium displaces some of theexchangeable aluminum. The low ionic strength counters the dilution effect on the exchange equilibrium by setting the saltconcentration of the solution closer to that expected in the soil solution. The pH va
29、lues obtained in the solution of calcium chlorideare slightly lower than those measured in water due to the release of more aluminum ions which then hydrolyses. Therefore, bothmeasurements are requiredneeded to fully define the character of the soils pH.5.3 For the purpose of thisthese test methodme
30、thods, the test soil must be specimens are sieved through a 2-mm 2.00 mm (No.10) sieve. Measurements on soils or soil fractions having particle sizes larger than 22.0 mm by thisthese test methodmethods maybe invalid. If soil or soil fractions with particles larger than 22.0 mm are used, it must be s
31、tated in the report since the results maybe significantly different.5.4 All water used for this test method must be ASTM Type III or better. Type III water is defined by Specification D1193. Itis prepared by distillation, ion exchange, reverse osmosis, or a combination thereof.NOTE 2The quality of t
32、he result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of theequipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objectivetesting/sampling/inspection/etc. Us
33、ers of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliableresults depend on many factors; Practice D3740 provides a means of evaluating some of those factors.6. Interferences6.1 This test method as measured by When using Method A, a pH
34、 probe has possible interferences due to a suspension effector sedimentation potential. Users interested in a detailed discussion of the mechanism of this effect can find it in Refs (5) and (6).)provide a more detailed discussion of the effect of this mechanism.6.2 This effect is the main reason Tes
35、t Method G51 can not cannot be used for general measurement of pH outside of that forcorrosion analysis. Test Method G51 measures pH (anpH, an aqueous parameter)parameter, without adding any aqueous phase tothe soil. This lack of aqueous phase results in excessive soil particle-pH probe contact that
36、 overestimates the activity of thehydrogen ions in solution and is therefore unacceptable for general soil analysis.D4972 1826.3 The suspension effect can be mitigated by careful attention to 10.112.2.7. Apparatus7.1 Method A, pH MeterPotentiometer equipped with an electrode system. Follow the manuf
37、acturers instructions for the pHmeter used. A silver/silver chloride electrode system or similar is also acceptable.Use one of the following devices to measure thepH.7.1.1 pH MeterPotentiometer equipped with an electrode system with a readability to the nearest 0.1 pH unit and an accuracyof 60.1 pH
38、unit or better. Follow the manufacturers instructions for the pH meter used. A silver/silver chloride electrode systemor similar is also acceptable.7.1.2 pH PaperpH-sensitive paper having a typical range from 1 to 12 with sensitivity to the nearest 0.5 pH unit or better.The range of the paper may va
39、ry based on the typical pH of the materials being tested. It is acceptable to use paper ranging betweenother values as long as the range is large enough to bracket the expected pH result.7.2 Method B, pH PaperBalancepH paper sensitive to a pH range from 1 to 12, with resolution to the nearest 0.2pHB
40、alances shall conform to the requirements of Specification D4753unit7.2.1 To determine the mass of the specimen, the balance shall have readability without estimation of 0.1 g or better. Thecapacity of this balance will need to exceed the mass of the container plus soil. In general, a balance with a
41、 minimum capacityof 300 g is sufficient.7.3 Separation Sieve2.00 mm (No. 10) sieve used to separate the coarse material from the representative sample. This sieveis subjected to rough operation and shall not be used for quantitative testing.7.4 Specimen-Mixing ContainerA glass beaker or equivalent i
42、nert container with enough capacity to hold the specimen andthe test water. Usually, a 100 mL to 250 mL glass beaker is large enough.7.5 Drying Oven (Optional)Vented, thermostatically controlled oven capable of maintaining uniform temperatures of 105 65C and 130 6 5C as needed throughout the drying
43、chamber. These requirements typically require the use of a forced-draft oven.7.6 Volumetric Flask or CylinderTwo, glass or plastic; one each with capacities of 1 L and 2 L. Required for making calciumchloride hydrate solutions, otherwise, they are optional.7.7 Thermometric DeviceA thermometric devic
44、e capable of measuring the temperature range within which the test is beingperformed readable to 0.5C or better and having an accuracy of at least 60.5C.7.8 Miscellaneous ItemsItems such as a wash/rinse bottle (squirt bottle), rubber scraper, spatula, plastic or glass containersto hold reagents, and
45、 stirring rod may be useful.8. Reagents8.1 Purity of ReagentsReagent grade chemicals should be used in all tests. Unless otherwise indicated, it is intended that allreagents should conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, wheresuch speci
46、fications are available.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficient purityto permit its use without lessening the accuracy of the determination.8.2 Purity of Test WaterAll water used for this test method must beASTM Type III or better. Type III wate
47、r is defined byTypeIII water in accordance with Specification D1193. It is prepared by distillation, ion exchange, reverse osmosis, or a combinationthereof. or distilled/deionized water with a pH between 6.5 and 7.5.8.3 Acid Potassium Phthalate Buffer Solution Buffer Solutions(0.05Buffer Msolutions)
48、Dissolve 10.21 g (dried 1 hour at 10565C) of potassium phthalate in water and dilute to 1 L. The pH of this solution should be 4.0 at 20C. Protect the solution againstevaporation and against contamination with molds. Replace are commercially available and providing they meet the purity ofreagents as
49、 described above, they are an acceptable alternative to making buffer solutions. The following NIST traceable buffersolutions are typically needed: pH of 4.0, 7.0, and 10.0. When making buffer solutions, refer to Annex A1the solution when moldis noticed. The effect of temperature is as follows: for the necessary chemicals and instructions.C pH5 to 37 4.0This illustrates that the pH of the solution does not change over the range in temperature from 5 to 37C.8.4 Calcium Chloride Hydrate Stock Solution (CaCl2 2H2O)(1.0Using Mthe)Dissolve 1 L vol
