1.1 本试验方法涵盖了通过直接加热干燥来测定土壤含水量的程序，例如使用热板、炉子或喷灯，其中热量施加在容器上，而不是直接施加在土壤上。 1.2 此试验方法可替代试验方法 D2216 当需要更快速的结果来加快测试的其他阶段并且不太准确的结果是可接受的时。 1.3 当本测试方法与测试方法之间存在准确性问题时 D2216 出现，测试方法的结果 D2216 将被使用。 1.4 该试验方法适用于大多数土壤类型。 对于一些土壤，如含有大量的海洛石、云母、蒙脱石、石膏或其他水合材料的土壤，高度有机的土壤或含有溶解固体的土壤（如海洋沉积物中的盐），由于可能加热到110°C以上，或者缺乏解释先前溶解的沉淀固体存在的方法，因此该试验方法可能无法得出可靠的含水量值。 1.5 单位-- 以国际单位制表示的数值应视为标准。本标准中不包括其他计量单位。 根据规范，使用“标准”系统识别筛网名称 E11 ，例如2.0毫米和19毫米，然后是10号的“替代”系统和 3. / 4. 在里面分别放在括号中。以SI以外的单位报告试验结果不应被视为不符合本标准。 1.6 所有观测值和计算值必须符合实践中制定的有效数字和舍入准则 D6026 ，除非本标准另有规定。 1.6.1 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。所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；并且通常的做法是增加或减少报告数据的有效位数以与这些考虑相称。考虑设计分析方法中使用的有效数字超出了本标准的范围。 1.6.2 如果含水量将用于计算其他关系，如湿质量与干质量或反之亦然、湿单位重量与干单位重量或反之亦然以及总密度与干密度或反之亦然，则有效数字尤为重要。 例如，如果在上述任何计算中都需要四个有效数字，则必须记录含水量，精确到0.1 %, 含水量低于100 %. 这是因为1加上含水量（不是百分比）将有四个有效数字，而不管含水量的值是多少（低于100 %); 即1加0.1/100 = 1.001，一个有四个有效数字的值。同时，如果三个有效数字是可接受的，则可以将含水量记录到最接近的1 %. 1.7 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。 1.8 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====== 5.1 土壤的含水量在实验室和现场的整个专业实践中都被使用。 试验方法的使用 D2216 因为水含量的测定可能是耗时的，并且有时需要更方便的方法。直接加热干燥就是这样一种方法。该试验方法的结果已被证明具有令人满意的准确性，可用于现场控制试验，如测定含水量和测定土壤的原位干容重。 5.2 使用直接加热测定含水量的主要反对意见是土壤过热的可能性，从而产生比试验方法测定的含水量更高的含水量 D2216 。虽然没有消除这种可能性，但本试验方法中的增量干燥程序将减少其影响。一些热源的设置或控制也可用于减少过热。宽松的盖子或外壳也可以用来减少过热，同时有助于均匀的热量分布。 5.3 土壤在受到直接加热时的行为取决于其矿物学成分，因此，没有一种程序适用于所有类型的土壤或热源。该测试方法的一般程序适用于所有土壤，但测试细节可能需要根据测试土壤进行调整。 5.4 当在给定场地的相同或相似土壤上重复使用该试验方法时，通常可以通过对该试验方法和试验方法的结果进行多次比较来确定校正系数 D2216 。当差异在多次比较中一致时，修正系数有效，并在定期指定的基础上重新确认。 5.5 当需要精确结果时，或者当含水量的微小变化会影响其他测试方法的结果时，例如测量含水量的细微变化可能影响验收或拒收的临界情况时，这种测试方法是不合适的。 5.6 该试验方法不适用于已知含有易燃有机物或污染物的试样，在这种情况下应使用其他试验方法。 注1: 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 通常被认为有能力进行合格和客观的测试/取样/检查等。本标准的用户应注意遵守实践 D3740 其本身不能保证可靠的结果。 可靠的结果取决于许多因素；实践 D3740 提供了评估其中一些因素的方法。

1.1 This test method covers procedures for determining the water content of soils by drying with direct heat, such as using a hotplate, stove or a blowtorch, where the heat is applied to the container and not directly to the soils. 1.2 This test method can be used as a substitute for Test Methods D2216 when more rapid results are desired to expedite other phases of testing and less accurate results are acceptable. 1.3 When questions of accuracy between this test method and Test Methods D2216 arise, the results of Test Methods D2216 will be used. 1.4 This test method is applicable for most soil types. For some soils, such as those containing significant amounts of halloysite, mica, montmorillonite, gypsum, or other hydrated materials, highly organic soils or soils that contain dissolved solids, (such as salt in the case of marine deposits), this test method may not yield reliable water content values due to the potential for heating above 110°C or lack of means to account for the presence of precipitated solids that were previously dissolved. 1.5 Units— The values stated in SI units are to be regarded as standard. No other units of measure are included in this standard. The sieve designations are identified using the “standard” system in accordance with Specification E11 , such as 2.0-mm and 19-mm, followed by the “alternative” system of No. 10 and 3 / 4 -in., respectively, in parentheses. 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 must conform to the guidelines for significant digits and rounding established in Practice D6026 , unless otherwise superseded by this standard. 1.6.1 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 analysis methods for design. 1.6.2 Significant digits are especially important if the water content will be used to calculate other relationships such as moist mass to dry mass or vice versa, wet unit weight to dry unit weight or vice versa, and total density to dry density or vice versa. For example, if four significant digits are required in any of the above calculations, then the water content must be recorded to the nearest 0.1 %, for water contents below 100 %. This occurs since 1 plus the water content (not in percent) will have four significant digits regardless of what the value of the water content is (below 100 %); that is, 1 plus 0.1/100 = 1.001, a value with four significant digits. While, if three significant digits are acceptable, then the water content can be recorded to the nearest 1 %. 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. ====== Significance And Use ====== 5.1 The water content of a soil is used throughout professional practice both in the laboratory and in the field. The use of Test Methods D2216 for water content determination can be time consuming and there are occasions when a more expedient method is desirable. Drying by direct heating is one such method. Results of this test method have been demonstrated to be of satisfactory accuracy for use in field control testing, such as in the determination of water content, and in the determination of in-place dry unit weight of soils. 5.2 The principal objection to the use of the direct heating for water content determination is the possibility of overheating the soil, thereby yielding a water content higher than would be determined by Test Methods D2216 . While not eliminating this possibility, the incremental drying procedure in this test method will reduce its effects. Some heat sources have settings or controls that can also be used to reduce overheating. Loose fitting covers or enclosures can also be used to reduce overheating while assisting in uniform heat distribution. 5.3 The behavior of a soil when subjected to direct heating is dependent on its mineralogical composition, and as a result, no one procedure is applicable for all types of soils or heat sources. The general procedure of this test method applies to all soils, but test details may need to be tailored to the soil being tested. 5.4 When this test method is to be used repeatedly on the same or similar soil from a given site, a correction factor can usually be determined by making several comparisons between the results of this test method and Test Methods D2216 . A correction factor is valid when the difference is consistent for several comparisons, and is reconfirmed on a regular specified basis. 5.5 This test method is not appropriate when precise results are required, or when minor variations in water content will affect the results of other test methods, such as borderline situations where small variations in the measured water content could affect acceptance or rejection. 5.6 This test method is not appropriate for specimens known to contain flammable organics or contaminants, and other test methods should be utilized in these situations. Note 1: 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 facility 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.