Significance and Use 5.1 The soil-lime pH test is performed as a test to indicate the soil-lime proportion needed to maintain the elevated pH necessary for sustaining the reactions required to stabilize a soil. The test derives from Eades and Grim.4 5.2 Performance tests are normally conducted in a laboratory to verify the results of this test method. 5.3 This test method will not provide reliable information relative to the potential reactivity of a particular soil, nor will it provide information on the magnitude of increased strength to be realized upon treatment of this soil with the indicated percentage of lime. 5.4 This test method can be used to estimate the percentage of lime as hydrated lime or quicklime needed to produce a lime stabilized soil. Common candidate soils contain clay minerals and have a Plasticity Index ≥10. 5.5 Agricultural lime (crushed limestone) will not stabilize soil. Note 2: The quality of the result produced by this standard is dependent on the competence of the personnel performing it and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. 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 provides a means of evaluating some of those factors.Scope 1.1 This test method provides a means for estimating the soil-lime proportion requirement for stabilization of a soil. This test method is performed on soil passing the 425μm (No. 40) sieve. The optimum soil-lime proportion for soil stabilization is determined by tests of specific characteristics of stabilized soil such as unconfined compressive strength or plasticity index. 1.2 Some highly alkaline by-products (lime kiln dust, cement kiln dust, carbide lime, and so forth) have been successfully used to stabilize soil. This test method is not intended for these materials and any such product would need to be tested for specific characteristics as indicated in 1.1. 1.3 This test method is used to determine the percentage of lime that results in a soil-lime pH of approximately 12.4. Note 1: Under ideal laboratory conditions of 25°C and sea level elevation, the pH of the lime-soil-water solution should be 12.4. 1.4 Lime is not an effective stabilizing agent for all soils. Some soil components such as sulfates, phosphates, organics, and iron can adversely affect soil-lime reactions and may produce erroneous results using this test method. 1.5 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026. 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 user’s 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 these test methods to consider significant digits used in analysis 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.
