1、Standard Method of Test for Determining pH of Soil for Use in Corrosion Testing AASHTO Designation: T 289-91 (2013) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1a T 289-1 AASHTO Standard Method of Test for Dete
2、rmining pH of Soil for Use in Corrosion Testing AASHTO Designation: T 289-91 (2013) 1. SCOPE 1.1. This test method describes procedures and apparatus for determining a pH value for corrosion testing by use of a pH meter. 1.2. The principal use of the test is to supplement soil-resistivity measuremen
3、ts and thereby identify conditions under which the corrosion of metals in the soil may be sharply accentuated. This standard is divided into two parts. The first part involves obtaining and preparing the sample to size for testing. The second part describes the test method for determining the pH of
4、soil. 1.3. The values stated in SI units are to be regarded as the standard. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 92, Wire-Cloth Sieves for Testing Purposes M 231, Weighing Devices Used in the Testing of Materials T 2, Sampling of Aggregates T 248, Reducing Samples of Aggregate to Testin
5、g Size 2.2. ASTM Standard: E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications PART IINITIAL PREPARATION OF TEST SAMPLES 3. SCOPE 3.1. This method covers the dry preparation of soil and soil-aggregate samples for determining a soils pH. 3.2.
6、The following applies to all specified limits in this standard: For the purpose of determining conformance with these specifications, an observed value or calculated value shall be rounded off “to the nearest unit” in the last right-hand place of figures used in expressing the limiting value, in acc
7、ordance with ASTM E29. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 289-2 AASHTO 4. APPARATUS 4.1. SievesA series of sieves of the following sizes: 6.3 mm (1/4in.), 4.75 mm (No. 4), 2.00 mm (N
8、o. 10), and a pan. The sieve shall conform to M 92, Sieves for Testing Purposes (Note 1). 4.2. BalanceThe balance shall have sufficient capacity, be readable to 0.1 percent of the sample mass, or better, and conform to the requirements of M 231. 4.3. Drying ApparatusAny suitable device capable of dr
9、ying samples at a temperature not exceeding 60C (140F). 4.4. Pulverizing ApparatusEither a mortar and rubber-covered pestle or any device suitable for breaking up the aggregations of soil particles without reducing the size of the individual grains (Note 2). 4.5. Sample SplitterA suitable riffle sam
10、pler or sample splitter for proportional splitting of the sample and capable of obtaining representative portions of the sample without appreciable loss of fines. The width of the container used to feed the riffle sampler splitter should be equal to the total combined width of the riffle chutes. Pro
11、portional splitting of the sample on a canvas cloth is also permitted. Note 1The sieve sizes that have an opening size of 6.3 mm (1/4in.) or larger shall conform to the requirements specified in M 92, excluding Column No. 7. The exclusion of Column 7 permits the use of heavier screens in nonstandard
12、 frames that are larger than the 203.2 mm (8 in.) round frames. Note 2Other types of apparatus are satisfactory if the aggregations of soil particles are broken up without reducing the size of the individual grains. 5. SAMPLE SIZE 5.1. The amount of soil material required to perform the test is as f
13、ollows: Test Approx Mass (g) Sieve Size Finer Than: pH 100 2.00 mm (No.10) 6. INITIAL PREPARATION OF TEST SAMPLES 6.1. The sample as received shall be in a moist condition for pH testing purposes. If the sample is too wet, it may be dried to a moist condition in air or a drying apparatus not exceedi
14、ng 60C (140F) prior to sample selection (Note 3). A representative test sample to perform the pH test shall then be obtained with the sampler, or by splitting or quartering as per T 248. Note 3Samples dried in an oven or other drying apparatus at a temperature not exceeding 60C (140F) are considered
15、 to be air dried. 6.2. The portion of the sample selected for pH testing shall be separated into fractions by one of the following methods: 6.2.1. Alternate Method Using 2.00-mm (No. 10) SieveThe sample shall be separated into two fractions using a 2.00-mm sieve. The fraction retained on the sieve s
16、hall be ground with a pulverizing apparatus until the aggregations of soil particles are broken into separate grains. The ground soil shall then be separated into two fractions using the 2.00-mm sieve. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved
17、. Duplication is a violation of applicable law.TS-1a T 289-3 AASHTO 6.2.2. Alternate Method Using 4.75-mm and 2.00-mm (No. 4 and No. 10) SievesThe sample shall first be separated into two fractions using a 4.75-mm sieve. The fraction retained on this sieve shall be ground with a pulverizing apparatu
18、s until the aggregations of soil particles are broken into separate grains and again separated on the 4.75-mm sieve. The fraction passing the 4.75-mm sieve shall be mixed thoroughly and, by the use of the sampler or by splitting and quartering, a representative portion adequate for testing shall be
19、obtained. This split-off portion shall then be separated on the 2.00-mm sieve and processed as in Section 6.2.1. 6.2.3. Alternate Method Using 6.3-mm and 2.00-mm (1/4-in. and No. 10) SievesThe sample shall first be separated into two fractions using a 6.3-mm sieve. The fraction retained on this siev
20、e shall be ground with a pulverizing apparatus until the aggregations of soil particles are broken into separate grains and again separated on the 6.3-mm sieve. The fraction passing the 6.3-mm sieve shall be mixed thoroughly and, by the use of the sampler or by splitting and quartering, a representa
21、tive portion adequate for testing shall be obtained. This split-off portion shall then be separated on the 2.00-mm sieve and processed as in Section 6.2.1. PART IIDETERMINATION OF SOIL PH 7. SCOPE 7.1. This section describes the procedure for determining soil pH. 8. APPARATUS 8.1. pH Metersuitable f
22、or laboratory or field analysis, with either one or two electrodes. 8.2. A 50-mL wide-mouth glass beaker or other suitable container. If lightweight material is to be tested, it may be necessary to increase the beaker size to a maximum of 250 mL. 8.3. A watch glass of suitable size to cover the beak
23、er or other container. 8.4. Standard Buffer Solutions of Known pH Valuesstandards to be used are pH of 4.0, 7.0, and 10.0. 8.5. Distilled water. 8.6. A teaspoon or small scoop. 8.7. A thermometer capable of reading 25 10C, to the nearest 0.1C. 8.8. SievesA 2.00 mm (No. 10) for preparing the sample a
24、nd a pan. The sieve shall conform to M 92, Wire-Cloth Sieves for Testing Purposes. 8.9. A glass stirring rod. 9. PROCEDURE 9.1. Of the material selected for testing, place a mass of 30.0 0.1 g of soil into the glass beaker or other suitable container. 9.2. Add 30.0 0.1 g of distilled water to the so
25、il sample. Stir to obtain a soil slurry and then cover with a watch glass. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1a T 289-4 AASHTO 9.3. The sample must stand for a minimum of 1 h, stirring e
26、very 10 to 15 min. This is to allow the pH of the soil slurry to stabilize. 9.4. Measure the temperature of the sample and adjust the temperature controller of the pH meter to that of the sample temperature. This adjustment should be done just prior to testing. On meters with an automatic temperatur
27、e control, follow the manufacturers instructions. 9.5. Standardize the pH meter by means of the standard solutions provided. Temperature and adjustments must be performed as stated under Section 9.4 (see Note 4). 9.6. Immediately before immersing the electrode(s) into the sample, stir well with a gl
28、ass rod. Place the electrode(s) into the soil slurry solution and gently turn the beaker or container to make good contact between the solution and the electrode(s). DO NOT place the electrode(s) into the soil; place them only into the soil slurry solution (see Note 5). 9.7. The electrode(s) require
29、 immersion for 30 s or longer in the sample before reading to allow the meter to stabilize. If the meter has an auto-read system, it will automatically signal when stabilized. 9.8. Read and record the pH value to the nearest tenth of a whole number. If the pH meter reads to the hundredth place, it i
30、s necessary to round off the result in accordance with the rounding-off method in ASTM E29. 9.9. Rinse off the electrode(s) well with distilled water, then dab lightly with tissues to remove any film formed on the electrode(s). CautionDo not wipe the electrode(s) as this may result in polarization o
31、f the electrode(s) and consequent slow response (see Note 6). Note 4To standardize the pH meter, use the 7.0 pH buffer standard solution plus the other standard solution that is nearest the estimated pH value of the sample to be tested. If the manufacturers instructions indicate a method other than
32、that noted above, then those instructions must be followed. Note 5When immersing electrode(s) into the glass beaker or container, care should be taken not to hit the bottom or side, causing damage to the electrode(s). Note 6If polarization does occur, as indicated by a slow response, rinse the elect
33、rode(s) and dab lightly again. 10. PRECAUTIONS 10.1. Periodically check for damage to the electrode(s). 10.2. The electrode tip should be kept moist during storage. Follow the manufacturers instructions. 11. REPORT 11.1. As specified in Section 9.8, report the pH value to the nearest tenth of a whole number in accordance with ASTM E29. 12. PRECISION AND BIAS 12.1. Data are not available at this time. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
