1.1 本试验方法概述了通过在微波炉中逐渐干燥土壤来测定土壤含水量的程序。 1.2 本试验方法可替代试验方法 D2216 当需要更快速的结果以加快测试的其他阶段时，可以接受精度稍低的结果。 1.3 当本试验方法和试验方法之间存在准确性问题时 D2216 试验方法 D2216 应为仲裁方法。 1.4 本试验方法适用于大多数土壤类型。对于某些土壤，例如含有大量埃洛石、云母、蒙脱石、石膏或其他水化材料的土壤、高度有机的土壤，或孔隙水含有大量溶解固体（如海洋沉积物中的盐）的土壤，由于可能加热到110°C以上，或缺乏说明先前溶解的沉淀固体存在的方法，本试验方法可能无法产生可靠的含水量值。 1.5 以国际单位制表示的数值应视为标准。使用另一个单元系统的测试方法的性能不应被视为不合格。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号和19号的“替代”系统 3. / 4. -英寸。，分别在括号中。 1.6 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 ，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。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； 通常的做法是增加或减少报告数据的有效位数，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。 1.6.2 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、湿容重与干容重或反之亦然、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需要四个有效数字，则必须将含水量记录到最接近的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，无论含水量的值是多少（低于100 %); 也就是说，1加0.1/100=1.001，一个具有四个有效数字的值。而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和健康实践，并确定监管限制的适用性。 参见第节 7. . ====意义和用途====== 5.1 土壤的含水量在实验室和现场的岩土工程实践中使用。试验方法的使用 D2216 因为水含量测定可能耗时，有时需要更方便的方法。使用微波炉就是这样一种方法。 5.2 使用微波炉测定含水量的主要反对意见是土壤可能过热，从而产生的含水量高于通过试验方法测定的含水量 D2216 . 虽然不排除这种可能性，但本试验方法中描述的增量干燥程序将使其影响最小化。 一些微波炉的设置低于全功率，这也可以用来减少过热。 5.3 当受到微波能量作用时，土壤的行为取决于其矿物成分，因此没有一种程序适用于所有类型的土壤。因此，本试验方法中推荐的程序旨在作为使用微波炉的指南。 5.4 本试验方法最适用于-4.75-mm（4号）筛孔大小的材料。可以测试较大尺寸的颗粒；然而，必须小心，因为颗粒破碎的机会增加。 5.5 当需要高精度的结果，或使用数据的测试对水分变化极为敏感时，使用该方法可能不合适。 5.6 由于样品在微波加热中暴露在局部高温下，土壤的物理特性可能会改变。 随着蒸发或化学转变，单个颗粒可能会发生脱脂。因此，建议本试验方法中使用的样品不得用于干燥后的其他试验。 注1: 本试验方法产生的结果质量取决于执行该试验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测试。本试验方法的使用者应注意遵守规程 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 This test method outlines procedures for determining the water content of soils by incrementally drying soil in a microwave oven. 1.2 This test method can be used as a substitute for Test Method D2216 when more rapid results are desired to expedite other phases of testing and slightly less accurate results are acceptable. 1.3 When questions of accuracy between this test method and Test Method D2216 arise, Test Method D2216 shall be the referee method. 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 in which the pore water contains significant amounts of 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 The values stated in SI units are to be regarded as the standard. Performance of the test method utilizing another system of units shall not be considered non-conformance. 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. 1.6 All observed and calculated values shall 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 engineering 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 has to 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 and health practices and determine the applicability of regulatory limitations prior to use. See Section 7 . ====== Significance And Use ====== 5.1 The water content of a soil is used throughout geotechnical engineering practice both in the laboratory and in the field. The use of Test Method D2216 for water content determination can be time consuming and there are occasions when a more expedient method is desirable. The use of a microwave oven is one such method. 5.2 The principal objection to the use of the microwave oven for water-content determination has been the possibility of overheating the soil, thereby yielding a water content higher than would be determined by Test Method D2216 . While not eliminating this possibility, the incremental drying procedure described in this test method will minimize its effects. Some microwave ovens have settings at less than full power, which can also be used to reduce overheating. 5.3 The behavior of a soil, when subjected to microwave energy, is dependent on its mineralogical compositions, and as a result no one procedure is applicable for all types of soil. Therefore, the procedure recommended in this test method is meant to serve as a guide when using the microwave oven. 5.4 This test method is best suited for minus 4.75-mm (No. 4) sieve sized material. Larger size particles can be tested; however, care must be taken because of the increased chance of particle shattering. 5.5 The use of this method may not be appropriate when highly accurate results are required, or the test using the data is extremely sensitive to moisture variations. 5.6 Due to the localized high temperatures that the specimen is exposed to in microwave heating, the physical characteristics of the soil may be altered. Degregation of individual particles may occur, along with vaporization or chemical transition. It is therefore recommended that samples used in this test method not be used for other tests subsequent to drying. Note 1: The quality of the results produced by this test method 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. Users of this test method 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.