1.1 这些试验方法包括测定粒状土壤的最大干容重。振动锤用于向土壤样本施加超载和压实力。此外，提出了一种可选计算方法，以根据测得的最大干密度和比重确定颗粒土有效压实的近似含水量范围。 1.2 这些试验方法适用于主要为颗粒状、自由排水的土壤，冲击压实不会产生明显的最佳含水量。 具体而言，这些试验方法适用于土壤: 1.2.1 最多35个 %, 以干质量计，如果通过40（425μm）筛的部分是非塑性的，则通过200（75μm）筛； 1.2.2 最多15个 %, 如果通过40号（425μm）筛的部分表现出塑性行为，则通过200号（75μm）筛的干质量。 1.3 此外，由于测试设备的限制和可用的超大校正程序，这些测试方法适用于以下土壤: 1.3.1 小于30 %, 以干质量计，保留在 3. / 4. -在中。（19.0-mm）筛，或其中 1.3.2 100 %, 按干质量，通过2英寸。（50 mm）筛。 1.4 这些试验方法通常会产生更高的最大干容重 1.2.1 和 1.2.2 与冲击压实相比，冲击压实中定义良好的水分-密度关系不明显。然而，对于一些含有15%以上 % 细粒，冲击压实的使用（试验方法 D698 或 D1557 )可能有助于评估适当的最大指数单位权重。 1.5 提供了四种替代试验方法，其中饱和试样与干燥试样和模具尺寸之间存在差异。所用方法应符合被测材料规范的规定。如果未指定方法，则应根据材料的最大粒径进行选择。 1.5.1 方法1A- 使用饱和材料和6英寸。（152.4-mm）直径模具；适用于最大粒径为 3. / 4. -在中。（19 mm）或以下，或30 % 或更少，以干质量计，保留在 3. / 4. -在中。（19 mm）筛。 1.5.2 方法1B- 使用饱和材料和11英寸。（279.4-mm）直径模具；适用于最大粒径为2英寸的材料。（50 mm）或以下 1.5.3 方法2A- 使用烘干材料和6英寸。（152.4-mm）直径模具；适用于最大粒径为 3. / 4. -在中。（19 mm）或以下，或30 % 或更少，以干质量计，保留在 3. / 4. -在中。（19 mm）筛。 1.5.4 方法2B- 使用烘干材料和11英寸。（279.4-mm）直径模具； 适用于最大粒径为2英寸的材料。（50 mm）或更小。 1.5.5 建议在开始新工作或遇到土壤类型变化时，同时采用饱和和干燥方法（方法1A和2A，或1B和2B），因为一种方法或另一种方法可能会导致最大干容重的更高值。虽然干法通常是为了方便，也因为可以更快地获得结果而首选，但作为一般规则，如果证明饱和法产生的最大干容重值明显更高，则应使用饱和法。 注1: 当在不同尺寸的模具中以相同的压实力测试材料时，结果略有不同。 1.6 如果试样包含5个以上 % 根据超大材料（粗粒）的质量，且材料不包括在试验中，必须使用实践对试样的单位重量和含水量或适当的现场密度试样进行修正 D4718 . 注2: 方法1A和2A（采用实践纠正程序 D4718 ，如果合适的话），已经证明，对于30%的材料，方法1B和2B的结果是一致的 % 或更少，以保留在 3. / 4. -在中。（19 mm）筛。因此，为了便于操作，建议使用方法1A或2A，除非由于土壤级配超过30，需要使用方法1B或2B %, 按干质量，保留在 3. / 4. -在中。（19 mm）筛。 1.7 该试验方法导致土壤的降解量最小（颗粒分解）。 当发生降解时，获得的最大单位重量通常会增加，当使用不同尺寸的模具测试给定土壤时，可能无法获得类似的测试结果。对于怀疑降解的土壤，应在压实试验前后对试样进行筛分分析，以确定降解量。 1.8 单位- 以英寸-磅为单位的数值应视为标准值。括号中给出的国际单位是数学转换，仅供参考，不被视为标准。 以英寸-磅单位以外的单位报告试验结果不应视为不符合本试验方法。 1.8.1 使用英寸-磅单位的重力系统。在这个系统中，磅（lbf）表示力（重量）的单位，而质量的单位是段塞。除非涉及动态（F=ma）计算，否则未给出缓动单元。 1.8.2 段塞质量单位几乎从未在商业实践中使用过；例如，与密度、平衡等有关。 因此，本标准中质量的标准单位为千克（kg）或克（g），或两者兼有。此外，括号中未给出/显示等效英寸-磅单位（slug）。 1.8.3 在美国，工程/建筑行业的常见做法是同时使用磅来表示质量单位（lbm）和力（lbf）。这隐含地结合了两个独立的单元系统；也就是说，绝对系统和引力系统。科学上不希望同时使用两套独立的英寸- 单一标准内的磅单位。如前所述，本标准包括英寸-磅单位的重力系统，不使用/呈现质量的段塞单位。然而，使用天平或天平记录磅质量（lbm）或记录密度（lbm/ft） 3. 不应视为不符合本标准。 1.8.4 术语密度和单位重量经常互换使用。密度是每单位体积的质量，而单位重量是每单位体积的力。在本标准中，密度仅以国际单位制表示。 密度确定后，单位重量以英寸-磅或国际标准单位或两者计算。 1.9 所有观察值和计算值应符合实践中确定的有效数字和舍入准则 D6026 . 1.9.1 本标准中用于规定如何收集/记录或计算数据的程序被视为行业标准。此外，它们代表了通常应保留的有效数字。使用的程序不考虑材料变化、获取数据的目的、特殊目的研究或用户目标的任何考虑因素，通常做法是增加或减少报告数据的有效数字，以与这些考虑因素相称。 考虑工程设计分析方法中使用的有效数字超出了本标准的范围。 1.10 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户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。 1.11 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 对于许多无粘性、自由排水的土壤，最大干容重是评估给定土体压实度状态的关键组成部分之一，该土体要么是自然产生的，要么是建造的（填土）。 5.2 将作为工程填料铺设的土壤压实至密实状态，以获得令人满意的工程特性，如抗剪强度、压缩性、渗透性或其组合。此外，经常对地基土进行压实，以改善其工程特性。 实验室压实试验为确定压实时达到所需工程特性所需的压实百分比和含水量，以及控制施工以确保达到所需单位重量和含水量提供了依据。 5.3 一般认为压实度是给定土体压实度状态的良好指标。然而，通过各种方法压实到给定压实状态的给定土壤的工程特性，如强度、压缩性和渗透性，可能会有很大的差异。 因此，在将土壤的工程特性与压实状态联系起来时，必须进行大量的工程判断。 5.4 经验表明，本文讨论的施工控制方面 5.2 在处理某些土壤时，极难实施或产生错误结果。子章节 5.4.1 , 5.4.2 和 5.4.3 描述典型问题土壤、处理此类土壤时遇到的问题以及这些问题的可能解决方案。 5.4.1 降级- 含有在压实过程中降解的颗粒的土壤是一个问题，尤其是当实验室压实过程中的降解比现场压实过程中的降解更多时，这是一个典型的问题。降解通常发生在颗粒残余土壤或骨料的压实过程中。当发生降解时，最大干容重增加 4. 因此，实验室最大值不能代表现场条件。在这些情况下，通常不可能在现场实现最大干容重。 5.4.1.1 设计和控制此类土壤压实的一种方法是使用试验填料来确定所需的压实度和获得该压实度的方法，然后使用方法规范来控制压实。方法规范的组成部分通常包含要使用的压实设备的类型和尺寸、提升厚度和遍数。 注3: 土方工程项目压实控制的成功实施，尤其是使用方法规范时，在很大程度上取决于“承包商”和“检查员”的质量和经验。 ” 5.4.2 间隙分级- 间隙级配土壤（包含许多大颗粒和有限小颗粒的土壤）是一个问题，因为压实土壤的空隙比通常情况下更大。为了处理这些大空隙，通常必须使用工程判断修改标准试验方法（实验室或现场）。 5.4.3 具有低角度和高细粒百分比的砾石土- 当使用饱和法时，具有低棱角性和高细粒百分比的砾石土可能导致干容重结果较差。 然而，当压实时的含水量接近饱和且没有游离水时，达到的干容重可能会导致比干法更高的值。最终，在致密化过程中，材料可能达到饱和状态。因此，对于这些土壤，含水量为1或2 % 小于 w 扎夫 对于使用干式方法获得的密度，建议使用。这是在11英寸测试中更令人担忧的问题。模具比在6英寸。模具 5.5 通过这些试验方法不一定能获得绝对最大干容重。 注4: 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 通常认为能够胜任和客观的测试/采样/检查等。本标准的用户应注意遵守惯例 D3740 本身不能确保可靠的结果。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因素的方法。

1.1 These test methods cover the determination of the maximum dry unit weight of granular soils. A vibrating hammer is used to impart a surcharge and compactive effort to the soil specimen. Further, an optional calculation is presented to determine the approximate water content range for effective compaction of granular soils based on the measured maximum dry density and specific gravity. 1.2 These test methods apply to primarily granular, free-draining soils for which impact compaction does not yield a clear optimum water content. Specifically, these test methods apply to soils: 1.2.1 with up to 35 %, by dry mass, passing a No. 200 (75-μm) sieve if the portion passing the No. 40 (425-μm) sieve is nonplastic; 1.2.2 with up to 15 %, by dry mass, passing a No. 200 (75-μm) sieve if the portion passing the No. 40 (425-μm) sieve exhibits plastic behavior. 1.3 Further, due to limitations of the testing equipment, and the available oversize correction procedures these test methods apply to soils in which: 1.3.1 less than 30 %, by dry mass, is retained on the 3 / 4 -in. (19.0-mm) sieve, or in which 1.3.2 100 %, by dry mass, passes the 2-in. (50-mm) sieve. 1.4 These test methods will typically produce a higher maximum dry unit weight for the soils specified in 1.2.1 and 1.2.2 than that obtained by impact compaction in which a well-defined moisture-density relationship is not apparent. However, for some soils containing more than 15 % fines, the use of impact compaction (Test Methods D698 or D1557 ) may be useful in evaluating what is an appropriate maximum index unit weight. 1.5 Four alternative test methods are provided, with the variation being in saturated versus dry specimens and mold size. The method used shall be as indicated in the specification for the material being tested. If no method is specified, the choice should be based on the maximum particle size of the material. 1.5.1 Method 1A— Using saturated material and a 6-in. (152.4-mm) diameter mold; applicable for materials with maximum particle size of 3 / 4 -in. (19-mm) or less, or with 30 % or less, by dry mass, retained on the 3 / 4 -in. (19-mm) sieve. 1.5.2 Method 1B— Using saturated material and an 11-in. (279.4-mm) diameter mold; applicable for materials with maximum particle size of 2-in. (50-mm) or less 1.5.3 Method 2A— Using oven-dry material and a 6-in. (152.4-mm) diameter mold; applicable for materials with maximum particle size of 3 / 4 -in. (19-mm) or less, or with 30 % or less, by dry mass, retained on the 3 / 4 -in. (19-mm) sieve. 1.5.4 Method 2B— Using oven-dry material and an 11-in. (279.4-mm) diameter mold; applicable for materials with maximum particle size of 2-in. (50-mm) or less. 1.5.5 It is recommended that both the saturated and dry methods (Methods 1A and 2A, or 1B and 2B) be performed when beginning a new job or encountering a change in soil type, as one method or the other may result in a higher value for the maximum dry unit weight. While the dry method is often preferred for convenience and because results can be obtained more quickly, as a general rule, the saturated method should be used if it proves to produce a significantly higher value for maximum dry unit weight. Note 1: Results have been found to vary slightly when a material is tested at the same compaction effort in different size molds. 1.6 If the test specimen contains more than 5 % by mass of oversize material (coarse fraction) and the material will not be included in the test, corrections must be made to the unit weight and water content of the test specimen or to the appropriate field in-place density test specimen using Practice D4718 . Note 2: Methods 1A and 2A (with the correction procedure of Practice D4718 , if appropriate), have been shown to provide consistent results with Methods 1B and 2B for materials with 30 % or less, by dry mass retained on the 3 / 4 -in. (19-mm) sieve. Therefore, for ease of operations, it is recommended to use Method 1A or 2A, unless Method 1B or 2B is required due to soil gradations having in excess of 30 %, by dry mass, retained on the 3 / 4 -in. (19-mm) sieve. 1.7 This test method causes a minimal amount of degradation (particle breakdown) of the soil. When degradation occurs, typically there is an increase in the maximum unit weight obtained, and comparable test results may not be obtained when different size molds are used to test a given soil. For soils where degradation is suspected, a sieve analysis of the specimen should be performed before and after the compaction test to determine the amount of degradation. 1.8 Units— The values stated in inch-pound units are to be regarded as standard. The SI units given in parentheses are mathematical conversions, which are provided for information purposes only and are not considered standard. Reporting of test results in units other than inch-pound units shall not be regarded as nonconformance with this test method. 1.8.1 The gravitational system of inch-pound units is used. In this system, the pound (lbf) represents a unit of force (weight), while the unit for mass is slugs. The slug unit is not given, unless dynamic (F = ma) calculations are involved. 1.8.2 The slug unit of mass is almost never used in commercial practice; for example as related to density, balances, and the like. Therefore, the standard unit for mass in this standard is either kilogram (kg) or gram (g), or both. Also, the equivalent inch-pound unit (slug) is not given/presented in parentheses. 1.8.3 It is common practice in the engineering/construction profession, in the United States, to concurrently use pounds to represent both a unit of mass (lbm) and of force (lbf). This implicitly combines two separate systems of units; that is, the absolute system and the gravitational system. It is scientifically undesirable to combine the use of two separate sets of inch-pound units within a single standard. As stated, this standard includes the gravitational system of inch-pound units and does not use/present the slug unit for mass. However, the use of balances or scales recording pounds of mass (lbm) or recording density in lbm/ft 3 shall not be regarded as nonconformance with this standard. 1.8.4 The terms density and unit weight are often used interchangeably. Density is mass per unit volume whereas unit weight is force per unit volume. In this standard, density is given only in SI units. After the density has been determined, the unit weight is calculated in inch-pound or SI units, or both. 1.9 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 1.9.1 The procedures used to specify how data are collected/recorded or calculated in this 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 this standard to consider significant digits used in analytical methods for engineering design. 1.10 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. 1.11 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 ====== 5.1 For many cohesionless, free-draining soils, the maximum dry unit weight is one of the key components in evaluating the state of compactness of a given soil mass that is either naturally occurring or is constructed (fill). 5.2 Soil placed as an engineered fill is compacted to a dense state to obtain satisfactory engineering properties such as shear strength, compressibility, permeability, or combinations thereof. Also, foundation soils are often compacted to improve their engineering properties. Laboratory compaction tests provide the basis for determining the percent compaction and water content needed at the time of compaction to achieve the required engineering properties, and for controlling construction to ensure that the required unit weights and water contents are achieved. 5.3 It is generally recognized that percent compaction is a good indicator of the state of compactness of a given soil mass. However, the engineering properties, such as strength, compressibility, and permeability of a given soil, compacted by various methods to a given state of compactness can vary considerably. Therefore, considerable engineering judgment must be used in relating the engineering properties of soil to the state of compactness. 5.4 Experience indicates that the construction control aspects discussed in 5.2 are extremely difficult to implement or yield erroneous results when dealing with certain soils. Subsections 5.4.1 , 5.4.2 , and 5.4.3 describe typical problem soils, the problems encountered when dealing with such soils, and possible solutions to these problems. 5.4.1 Degradation— Soils containing particles that degrade during compaction are a problem, especially when more degradation occurs during laboratory compaction than field compaction, as is typical. Degradation typically occurs during the compaction of a granular-residual soil or aggregate. When degradation occurs, the maximum dry unit weight increases 4 so that the laboratory maximum value is not representative of field conditions. Often, in these cases, the maximum dry unit weight is impossible to achieve in the field. 5.4.1.1 One method to design and control the compaction of such soils is to use a test fill to determine the required degree of compaction and the method to obtain that compaction, followed by the use of a method specification to control the compaction. Components of a method specification typically contain the type and size of compaction equipment to be used, the lift thickness, and the number of passes. Note 3: Success in executing the compaction control of an earthwork project, especially when a method specification is used, is highly dependent upon the quality and experience of the “contractor” and “inspector.” 5.4.2 Gap Graded— Gap-graded soils (soils containing many large particles with limited small particles) are a problem because the compacted soil will have larger voids than usual. To handle these large voids, standard test methods (laboratory or field) typically have to be modified using engineering judgment. 5.4.3 Gravelly Soils Possessing Low Angularity and High Percentage of Fines— Gravelly soils possessing low angularity and a high percentage of fines can lead to poor results for dry unit weight when using the saturated method. However, when water contents at the time of compaction are near saturation with no free water, the dry unit weight achieved may result in a higher value than that from the dry method. Ultimately, during densification, the material may reach a saturated state. Therefore, for these soils, a water content of 1 or 2 % less than the w zav for the density achieved by using the dry method is recommended. This is more of a concern for testing in the 11-in. mold than in the 6-in. mold. 5.5 An absolute maximum dry unit weight is not necessarily obtained by these test methods. Note 4: 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, and the like. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.