1.1 This test method uses a pH meter to measure the pH of as-received granular material that represents what will be used in the field for embankments, subgrades, and retaining wall backfill applications. The principal use of the test method is to supplement soil resistivity measurements to identify conditions under which the corrosion of metal embedded in granular material or in contact with the granular material may be sharply accentuated. 1.2 The pH of granular material is often specified by agencies to meet criteria that are necessary to prevent or reduce corrosion of metal objects embedded in the granular material used in embankments, subgrade, and retaining wall backfill. 1.3 The types of granular material that can be tested for pH using this standard are natural or manufactured coarse sand, natural or crushed stone, natural or crushed gravel, air-cooled blast furnace slag, and aggregates: lightweight, heavyweight, or normal weight. According to AASHTO M 145, these granular materials generally fall into AASHTO classification groups A-1, A-2-4, A-2-5, or A-3. The ideal material is a well-graded, free draining material that has less than 10-15 % passing the 75 m (No. 200) sieve. 1.4 This test is based on the volumetric method because the unit weight of the fill material will vary depending on source and project specifications. 1.5 UnitsThe values stated in SI units are to be regarded as the standard. Except the sieve designations, they are identified using the alternative system in accordance with Specification E11, such as 3 in. and No. 200, instead of the standard of 75 mm and 75 m, respectively. No other units of measurement are included in this standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard. 1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026, unless superseded by this test method. 1.6.1 The procedures used to specify how data are collected/recorded and calculated in the standard are regarded as the industry standard. In addition, they are representative of the significant digits that generally should be retained. The procedures used do not consider 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 significant digits of reported data to be commensurate with these considerations. It is beyond the scope of this test method to consider significant digits used in analysis methods for engineering data. 1.7 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, health and environmental practices and determine the applicability of regulatory limitations prior to use. 1.8 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Keywordsaggregate; coarse; coarse grained; coarse-grained material; granular; material; pH
Rationale: A pH test procedure does not exist for coarse-grained material. 1) D4972, The Standard Test Method for pH of Soils, does not work for coarse-grained material as most or all of the coarse-grained material is larger than the No. 10 sieve. D4972 -13, Section 5.3 verifies that this test is not appropriate for larger particle sizes. 5.3 For the purpose of this test method the test soil must be sieved through a No. 10 sieve (2 mm sieve mesh openings). Measurements on solids of soil fractions having particle sizes larger than 2 mm by this test method may be invalid. If soil or soil fractions with particles larger than 2 mm are used, it must be stated in the report since the results may be significantly different. 2) G51 - 95 (Reapproved 2012) Standard Test Method for Measuring pH of Soil for Use in Corrosion Testing, does not work for coarse-grained material either. This method is predominately used for in-place soil. It is also not appropriate to crush the coarse-grained material down so they pass the No. 10 sieve, as that would significantly misrepresent the material being placed in the field. 3) History: This standard was originally proposed under ASTM C09 jurisdiction and title Standard Test Method for Determining pH of Lightweight Aggregate. However C09 rejected it because this test is used for material placed in geotechnical applications and not in concrete
The title and scope are in draft form and are under development within this ASTM Committee.Back to Top
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