1.1 本试验方法描述了使用带放射源的核设备（以下简称为“测量仪”）测量土壤和土壤骨料的现场堆密度的程序。这些仪表与测试方法中描述的仪表不同 第6938页 只要: 1.1.1 这些仪表不包含用于测定被测材料含水量的系统（核或其他系统）。 1.1.2 这些测量仪具有足够低的光子产率，从而需要在正常操作期间包括对响应的背景辐射效应。 1.1.2.1 对于测试方法中描述的设备 第6938页 ，从大多数土壤中天然存在的放射性同位素中检测到的伽马射线的贡献（以下简称“背景”）与该设备用于测量- 场所堆积密度通常足够小，就其对测量精度的影响而言可以忽略不计。然而，对于这些低放射性测量仪，测量仪的伽马射线产量足够低，与测量仪伽马射线的贡献相比，大多数土壤的背景贡献不再可以忽略不计，并且这种背景的变化可能会对体积密度读数的准确性产生不利影响。 1.1.2.2 为了补偿在不同测试地点对低活性计量器测量的潜在不同背景贡献，必须将背景读数与在给定测试地点获得的计量器测量相结合。该背景读数用于测量仪进行的体积密度计算，目的是将这些背景对密度测量精度的影响降至最低。 1.2 有关限制，请参阅第节 5. 关于干扰。 1.3 土壤和土壤骨料的体积密度是通过伽马辐射的衰减来测量的，其中源被放置在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种方向）。 1.3.1 通过将检测到的伽马辐射速率与先前建立的校准数据进行比较，计算出单位体积质量的试样体积密度。 1.3.2 该装置既不能测量试样的干密度，也不能测量试样中的含水量。然而，该试验的结果可以与通过替代方法确定的每单位体积的含水量或水质量值一起使用，以确定试样的干密度。 1.4 对该测量仪进行校准，以读取土壤或土壤骨料的体积密度。 1.5 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 . 1.5.1 为了将测量或计算值与规定限值进行比较，测量或计算的值应四舍五入至规定限值中最接近的小数或有效数字。 1.5.2 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。 1.6 单位- 以国际单位制或英寸磅单位表示的数值应单独视为标准。每个系统中规定的值可能不是精确的等效值；因此，每个系统应独立于其他系统使用。将两个系统的值组合在一起可能会导致不符合标准。以SI以外的单位报告试验结果不应被视为不符合本标准。 1.7 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。 注1: 核密度计手册和参考材料，以及密度计显示器本身，通常将体积密度称为“湿密度”或“WD” 注2: 本标准中使用了“堆积密度”一词。这个术语在术语中有不同的定义 第653页 ，这取决于其使用的上下文。然而，对于本标准，“堆积密度”是指术语中定义的 第653页 ，“单位总体积中部分饱和或饱和土壤或岩石的总质量。” 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====== 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体积密度。如果土壤或土壤集料的含水量是通过单独的方法测定的，如《试验方法》中所述的方法，则试验结果可用于测定干密度 216年2月 , D4643天 , 第4944页 和 D4959天 . 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- 该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。 注3: 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 这本身并不能保证可靠的结果。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 bulk density of soil and soil-aggregate using nuclear equipment with radioactive sources (hereafter referred to simply as “gauges”). These gauges are distinct from those described in Test Method D6938 insofar as: 1.1.1 These gauges do not contain a system (nuclear or otherwise) for the determination of the water content of the material under measurement. 1.1.2 These gauges have photon yields sufficiently low as to require the inclusion of background radiation effects on the response during normal operation. 1.1.2.1 For the devices described in Test Method D6938 , the contribution of gamma rays detected from the naturally-occurring radioisotopes in most soils (hereafter referred to as “background”) compared to the contribution of gamma rays used by the device to measure in-place bulk density is typically small enough to be negligible in terms of their effect on measurement accuracy. However, for these low-activity gauges, the gamma ray yield from the gauge is low enough that the background contribution from most soils compared to the contribution of gamma rays from the gauge is no longer negligible, and changes in this background can adversely affect the accuracy of the bulk density reading. 1.1.2.2 In order to compensate for potentially differing background contribution to low-activity gauge measurements at different test sites, a background reading must be taken in conjunction with gauge measurements obtained at a given test site. This background reading is utilized in the bulk density calculation performed by the gauge with the goal of minimizing these background effects on the density measurement accuracy. 1.2 For limitations see Section 5 on Interferences. 1.3 The bulk density of soil and soil-aggregate is measured by the attenuation of gamma radiation where 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). 1.3.1 The bulk 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. 1.3.2 Neither the dry density nor the water content of the test sample is measured by this device. However, the results of this test can be used with the water content or water mass per unit volume value determined by alternative methods to determine the dry density of the test sample. 1.4 The gauge is calibrated to read the bulk density of soil or soil-aggregate. 1.5 All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026 . 1.5.1 For purposes of comparing, a measured or calculated value(s) with specified limits, the measured or calculated value(s) shall be rounded to the nearest decimal or significant digits in the specified limits. 1.5.2 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 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 Units— The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. Reporting test results in units other than SI shall not be regarded as nonconformance with this standard. 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. Note 1: Nuclear density gauge manuals and reference materials, as well as the gauge displays themselves, typically refer to bulk density as “wet density” or “WD.” Note 2: The term “bulk density” is used throughout this standard. This term has different definitions in Terminology D653 , depending on the context of its use. For this standard, however, “bulk density” refers to, as defined in Terminology D653 , “the total mass of partially saturated or saturated soil or rock per unit total volume.” 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 ====== 4.1 The test method described is useful as a rapid, nondestructive technique for in-place measurements of bulk density of soil and soil-aggregate. Test results may be used for the determination of dry density if the water content of the soil or soil-aggregate is determined by separate means, such as those methods described in Test Methods D2216 , D4643 , D4944 , and D4959 . 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 method is that Compton scattering is the dominant interaction and that the material is homogeneous. Note 3: 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 assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.