1.1 本规程涵盖了根据实验室测定的粒度分布、液限和塑性指数将矿物和有机矿物土壤分为七组的程序。当需要精确分类时，尤其是出于公路建设目的时，可以使用它。通过以下方式对每组土壤进行评估 组索引 ，这是根据经验公式计算的值。 注1: 包括组指数在内的组分类应有助于确定土方结构中使用的土壤材料的相对质量，特别是路堤、路基、底基层和基层。 然而，对于重要结构的详细设计，需要有关现场条件下土壤强度或性能特征的额外数据。 1.2 单位-- 以国际单位制表示的数值应视为标准。括号中给出的值仅供参考，不被视为标准值。以SI以外的单位报告试验结果不应被视为不符合本标准。 1.2.1 根据规范，使用“标准”系统识别筛网名称 E11 ，例如75 mm和75-μm，然后分别是3英寸和200号的“替代”系统（括号中显示）。 1.3 本标准并不旨在解决与其使用相关的所有安全问题（如有）。本标准的使用者有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.4 此实践提供了一套用于执行一个或多个特定操作的说明。 这种做法不能取代教育或经验，应与专业判断结合使用。并非此做法的所有方面都适用于所有情况。这一做法并不旨在代表或取代评判特定专业服务是否充分的护理标准，也不应在不考虑项目许多独特方面的情况下应用这一做法。本文件标题中的“标准”一词仅表示该文件已通过ASTM共识程序批准。 1.5 本国际标准是根据世界贸易组织技术性贸易壁垒委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认的标准化原则制定的。 ====意义和用途====== 4.1 所述实践根据规定的实验室测试结果将任何地理位置的土壤分类（包括组指数），以确定颗粒- 尺寸特性、液限和塑性指数。 4.2 分组符号和分组指数的分配可用于帮助评估公路和机场用土壤的重要特性。 4.3 该分类系统的各种分组在一般情况下与土壤的工程行为相关。此外，在一般情况下，土壤的工程行为与其组指数成反比。因此，该实践为岩土工程目的的任何现场或实验室调查提供了有用的第一步。 注2: 本标准产生的结果的质量取决于执行该标准的人员的能力以及所用设备和设施的适用性。符合实践标准的机构 D3740 通常被认为能够胜任和客观的测试/取样/检查。可靠的结果取决于许多因素；实践 D3740 提供了一种评估其中一些但不是全部因素的方法。

1.1 This practice covers a procedure for classifying mineral and organomineral soils into seven groups based on laboratory determination of particle-size distribution, Liquid Limit, and Plasticity Index. It may be used when a precise classification is required, especially for highway construction purposes. Evaluation of soils within each group is made by means of a group index , which is a value calculated from an empirical formula. Note 1: The group classification, including the group index, should be useful in determining the relative quality of the soil material for use in earthwork structures, particularly embankments, subgrades, subbases, and bases. However, for the detailed design of important structures, additional data concerning strength or performance characteristics of the soil under field conditions is required. 1.2 Units— The values stated in SI units are to be regarded as standard. The values given in parentheses are provided for information only and are not considered standard. Reporting of test results in units other than SI shall not be regarded as nonconformance with this standard. 1.2.1 The sieve designations are identified using the “standard” system in accordance with Specification E11 , such as 75-mm and 75-μm, followed by the “alternative” system of 3-in. and No. 200 (presented in parentheses), respectively. 1.3 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. 1.4 This practice offers a set of instructions for performing one or more specific operations. This practice cannot replace education or experience and should be used in conjunction with professional judgment. Not all aspects of this practice may be applicable in all circumstances. This practice is not intended to represent or replace the standard of care by which the adequacy of a given professional service must be judged, nor should this practice be applied without consideration of a project's many unique aspects. The word “Standard” in the title of this document means only that the document has been approved through the ASTM consensus process. 1.5 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. ====== Significance And Use ====== 4.1 The practice described classifies soils from any geographic location into groups (including group indexes) based on the results of prescribed laboratory tests that determine the particle-size characteristics, Liquid Limit, and Plasticity Index. 4.2 The assigning of a group symbol and group index can be used to aid in the evaluation of the significant properties of the soil for highway and airfield purposes. 4.3 The various groupings of this classification system correlate in a general way with the engineering behavior of soils. Also, in a general way, the engineering behavior of a soil varies inversely with its group index. Therefore, this practice provides a useful first step in any field or laboratory investigation for geotechnical engineering purposes. 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. Reliable results depend on many factors; Practice D3740 provides a means of evaluation some, but not all, of those factors.