1、Designation: D2976 15Standard Test Method forpH of Peat Materials1This standard is issued under the fixed designation D2976; 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 indicat
2、es the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers the electrometric measurementof the pH of peat materials, not soil. The standard formeasurement of pH in soil is Test Method D4972, nor doe
3、s thiscover the measurement of pH for corrosion testing, which iscontained in Test Method G51. These standards are beingintentionally kept separate for clarity at the request(s) of thegoverning sub-committees. It is a means of expressing thedegree of acidity or alkalinity of peat material suspended
4、inwater and 0.01 M calcium chloride solution.1.2 The values given in SI units are to be regarded as thestandard.1.3 The text of this standard references notes and footnoteswhich provide explanatory material. These notes and footnotesshall not be considered as requirements of the standard.1.4 All obs
5、erved and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026.1.4.1 The procedures used to specify how data are collected/recorded or calculated, in this standard are regarded as theindustry standard. In addition, they are representative
6、of thesignificant digits that generally should be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users objectives; and it is common practice toincrease or reduce significant digits of reported
7、data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1.5 This standard offers a set of instructions for performingone or more specific operations. This document cannot replaceeducation o
8、r experience and should be used in conjunctionwith professional judgment. Not all aspects of this practice maybe applicable in all circumstances. This ASTM standard is notintended to represent or replace the standard of care by whichthe adequacy of a given professional service must be judged,nor sho
9、uld this document be applied without consideration ofa projects many unique aspects. The word ”Standard” in thetitle of this document means only that the document has beenapproved though the ASTM consensus process.1.6 This standard does not purport to address all of thesafety concerns, if any, assoc
10、iated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFlui
11、dsD1193 Specification for Reagent WaterD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4972 Test Method for pH of SoilsD6026 Practice for Using Significant Digits in GeotechnicalDataG51 Test Metho
12、d for Measuring pH of Soil for Use inCorrosion Testing3. Terminology3.1 Definitions:3.1.1 For definitions of common technical terms used in thisstandard, refer to Terminology D653.4. Summary of Test Method4.1 The electrometric measurement of the pH of peat insuspensions of water and calcium chloride
13、 solutions is madewith a potentiometer using an electrode system, calibrated withbuffers of known pH.5. Significance and Use5.1 pH measurements are made in water and in calciumchloride solution because the pH readings in water can be1This test method is under the jurisdiction ofASTM Committee D18 on
14、 Soil andRock and is the direct responsibility of Subcommittee D18.22 on Soil as a Mediumfor Plant Growth.Current edition approved Nov. 1, 2015. Published December 2015. Originallyapproved in 1971. Last previous edition approved in 2004 as D2976 - 71 (2004),which was withdrawn July 2015 and reinstat
15、ed in November 2015. DOI: 10.1520/D2976-15.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.*A Summary of Chan
16、ges section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1modified by salts, such as fertilizer material, whereas theobserved pH in calcium chloride solution is virtually indepen-dent of the initia
17、l amount of salts present in the soil. pH valuesobtained in calcium chloride solution usually run about a 0.5 to0.8 pH unit lower than measurements in water due to release ofmore hydrogen ions by cation exchange.5.2 All water used for this test method must be ASTM TypeIII or better. Type III water i
18、s defined by Specification D1193.NOTE 1The quality of the result produced by this standard isdependent on the competence of the personnel performing it, and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of compe
19、tentand objective testing/sampling/inspection/etc. Users of this standard arecautioned that compliance with Practice D3740 does not in itself assurereliable results. Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.6. Apparatus6.1 pH MeterPo
20、tentiometer equipped with an electrodesystem. Follow the manufacturers instructions for the pHmeter used.7. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Other grades may be used, provided it is firstascertained that the reagent is of sufficiently high purity toper
21、mit its use without lessening the accuracy of the determi-nation.7.2 Purity of WaterWater shall be ASTM Type III orbetter. Use water with a pH of not less than 6.5 nor more than7.5, obtained by boiling distilled water for 15 min and coolingunder carbon dioxide-free conditions.7.3 Acid Potassium Phth
22、alate Buffer Solution (0.05 M)Dissolve 10.21 g (dried1hat1056 5C) of potassiumphthalate (NBS Standard Samples) in water and dilute to 1 L.Protect the solution against evaporation and contaminationwith molds. Replace the solution when mold is apparent. Theeffect of temperature is as follows:C pH5to24
23、 4.0025 to 33 4.0134 to 37 4.027.4 Calcium Chloride, Stock Solution (1.0M)Dissolve 147g of CaCl22H2O in distilled water in a 1-L volumetric flask,cool, dilute to volume with distilled water, and mix.7.5 Calcium Chloride Solution (0.01M)Dilute 20.0 mL ofstock 1.0 M CaCl2solution to 2 L with distilled
24、 water. The pHof this solution should be between 5 and 6.5.7.6 Phosphate Buffer Solution (0.025M)Dissolve 3.40 gof KH2PO4and 3.55 g of Na2HPO4(NBS Standard Samples186 I and II) in water and dilute to 1 L. Dry salts2hat130Cbefore use. Effect of temperature on pH is:C pH0 6.9810 6.9220 6.8830 6.8540 6
25、.838. Calibration of pH Meter8.1 Calibrate the pH meter using the acid potassium phtha-late and phosphate buffer solutions. Suitable commerciallyavailable NIST traceable calibration solutions are also accept-able.9. Procedure9.1 pH in Distilled WaterWeigh out about3gofair-driedpeat or about the equi
26、valent amount of moist material. Placeinto a 100-mL beaker. Add 50 mL of distilled water. Additionalwater may be needed for very fibrous materials, such assphagnum moss peat. Let soak with occasional stirring for 30min. Read on pH meter.9.2 pH in 0.01 M CaCl2SolutionWeigh out about 3.0 g ofair-dried
27、 peat or the equivalent amount of moist material. Placeinto a 100-mL beaker. Add 50 mL of 0.01 M CaCl2solution.Let soak with an occasional stirring for 30 min. Read on pHmeter.10. Report: Test Data Sheet(s)/Form(s)10.1 Record as a minimum the following general informa-tion:10.1.1 Sample/specimen ide
28、ntifying information, such asProject No., Boring No., Sample No., Depth, etc.10.1.2 Any special selection and preparation process, suchas removal of gravel or other materials.10.1.3 Technician name, method used and date.10.2 Record as a minimum the following test information:10.2.1 Report the pH of
29、the peat to the first decimal place(0.1) and specify whether it is pH in distilled water or pH incalcium chloride solution. All measured and calculated valuesshall conform to the guidelines for significant digits androunding established in Practice D6026.11. Precision and Bias11.1 PrecisionTest data
30、 on precision is not presented dueto the nature of the peat materials tested by this method. It iseither not feasible or too costly at this time to produce multiplespecimens that have uniform chemical properties. Any varia-tion observed in the data is just as likely to be due to specimenvariation as
31、 to operator or laboratory testing variation. Sub-committee D18.22 is seeking any data from the users of thisstandard that might be used to make a limited statement onprecision.11.2 BiasThere is no accepted reference value for this testmethod, therefore, bias cannot be determined.12. Keywords12.1 pe
32、at; pH; water penetration; water retentionD2976 152SUMMARY OF CHANGESIn accordance with Committee D18 policy, this section identifies the location of changes to this standard sincethe last edition (1971(Reapproved 2004) that may impact the use of this standard. (November 1, 2015)(1) Revised Section
33、1.(2) Added Referenced Documents and Terminology sections.(3) Added reference to ASTM Type III water.(4) Corrected Reagent mixing directions.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this
34、 standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five year
35、s andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committ
36、ee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428
37、-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 153
