1.1 本试验方法描述了使用核设备（以下简称“测量仪”）测量土壤和土壤骨料的现场密度和湿度的程序。材料的密度可以通过直接透射、反向散射或反向散射/气隙比方法来测量。无论用于密度的模式如何，都以反向散射模式在表面测量水（水分）含量。 1.1.1 有关限制，请参阅第节 5. 关于干扰。 1.2 土壤和土壤骨料的总密度或湿密度是通过伽马辐射的衰减来测量的，其中，在直接传输中，源被放置在高达300毫米（12英寸）的已知深度，探测器保留在表面上（一些测量仪可能会颠倒这一方向）；或者在反向散射或反向散射/气隙中，源和检测器都保留在表面上。 1.2.1 通过将伽马辐射的探测速率与先前建立的校准数据进行比较，计算出单位体积试样的质量密度。 1.2.2 试样的干密度是通过从试样的湿密度中减去每单位体积的水质量来获得的（第 11 ). 大多数仪表直接显示此值。 1.3 对该量表进行校准，以读取每单位体积土壤或土壤骨料的水质量。除以水的密度，再乘以100，单位体积的水质量等于体积含水量。单位体积的水质量是由氢（水的一种成分）对快中子的热化或减速决定的。中子源和热中子探测器都位于被测材料的表面。工程和施工活动中最普遍的含水量称为重量含水量w，是孔隙空间中的水质量与固体总质量的比率，以百分比表示。 1.4 提供了两种替代程序。 1.4.1 程序A 描述了一种直接传输方法，其中探针穿过量规的底部延伸到预先形成的孔中达到所需的深度。直接传输是首选方法。 1.4.2 程序B 涉及使用专用的反向散射仪或处于反向散射位置的探针。这将伽马和中子源以及探测器放置在同一平面上。 1.4.3 标记测试区域，以便将测量仪放置在测试位置上，并将探针与孔对齐。 1.5 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。以国际单位制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应符合实践中制定的有效数字和四舍五入指南 D6026型 . 1.6.1 本标准中用于规定如何收集、记录和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数字以与这些考虑相称。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。 1.7 限制- 本试验方法不适用于干净的砾石或干净的碎石，因为过多的表面空隙可能会影响仪表测量。 1.8 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。 1.9 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 所描述的测试方法是一种快速、无损的技术，可用于现场测量土壤和土壤骨料的湿密度和含水量，以及确定干密度。 4.2 该试验方法用于施工中使用的压实土和土骨料混合物的质量控制和验收试验，也用于研究和开发。 无损性质允许在单个测试位置进行重复测量，并对结果进行统计分析。 4.3 密度- 这些方法固有的基本假设是康普顿散射是主要的相互作用，并且材料是均匀的。 4.4 含水量- 试验方法固有的基本假设是，土壤或土壤骨料中存在的氢离子以水的形式存在，由试验方法得出的含水量定义 216年2月 ，并且材料是均匀的。（参见 5.2 ) 注1: 该标准测试方法产生的结果的质量取决于执行该方法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 第3740页 通常被认为能够胜任和客观的测试/取样/检查等。 本标准的使用者应注意遵守实践 第3740页 本身并不能确保可靠的结果。可靠的结果取决于许多因素；实践 第3740页 提供了一种评估其中一些因素的方法。

1.1 This test method describes the procedures for measuring in-place density and moisture of soil and soil-aggregate by use of nuclear equipment (hereafter referred to as “gauge”). The density of the material may be measured by direct transmission, backscatter, or backscatter/air-gap ratio methods. Measurements for water (moisture) content are taken at the surface in backscatter mode regardless of the mode being used for density. 1.1.1 For limitations see Section 5 on Interferences. 1.2 The total or wet density of soil and soil-aggregate is measured by the attenuation of gamma radiation where, in direct transmission, the source is placed at a known depth up to 300 mm (12 in.) and the detector(s) remains on the surface (some gauges may reverse this orientation); or in backscatter or backscatter/air-gap the source and detector(s) both remain on the surface. 1.2.1 The density of the test sample in mass per unit volume is calculated by comparing the detected rate of gamma radiation with previously established calibration data. 1.2.2 The dry density of the test sample is obtained by subtracting the water mass per unit volume from the test sample wet density (Section 11 ). Most gauges display this value directly. 1.3 The gauge is calibrated to read the water mass per unit volume of soil or soil-aggregate. When divided by the density of water and then multiplied by 100, the water mass per unit volume is equivalent to the volumetric water content. The water mass per unit volume is determined by the thermalizing or slowing of fast neutrons by hydrogen, a component of water. The neutron source and the thermal neutron detector are both located at the surface of the material being tested. The water content most prevalent in engineering and construction activities is known as the gravimetric water content, w, and is the ratio of the mass of the water in pore spaces to the total mass of solids, expressed as a percentage. 1.4 Two alternative procedures are provided. 1.4.1 Procedure A describes the direct transmission method in which the probe extends through the base of the gauge into a pre-formed hole to a desired depth. The direct transmission is the preferred method. 1.4.2 Procedure B involves the use of a dedicated backscatter gauge or the probe in the backscatter position. This places the gamma and neutron sources and the detectors in the same plane. 1.4.3 Mark the test area to allow the placement of the gauge over the test site and to align the probe to the hole. 1.5 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 the test results in units other than SI shall not be regarded as nonconformance with this standard. 1.6 All observed and calculated values shall conform to the guide 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 this standard are regarded as the industry standard. In addition, they are representative of the significant digits that should generally 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. 1.7 Limitations— This test method is not applicable to clean gravel or clean crushed rock due to excessive surface voids which have the potential to affect gauge measurements. 1.8 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. 1.9 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 test method described is useful as a rapid, nondestructive technique for in-place measurements of wet density and water content of soil and soil-aggregate and the determination of dry density. 4.2 The test method is used for quality control and acceptance testing of compacted soil and soil-aggregate mixtures as used in construction and also for research and development. The nondestructive nature allows repetitive measurements at a single test location and statistical analysis of the results. 4.3 Density— The fundamental assumptions inherent in the methods are that Compton scattering is the dominant interaction and that the material is homogeneous. 4.4 Water Content— The fundamental assumptions inherent in the test method are that the hydrogen ions present in the soil or soil-aggregate are in the form of water as defined by the water content derived from Test Methods D2216 , and that the material is homogeneous. (See 5.2 ) Note 1: The quality of the result produced by this standard 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/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.