1.1 这些试验方法包括通过伽马辐射测定未硬化和硬化混凝土（包括碾压混凝土）的现场密度。有关核试验的说明，请参阅 附录X1 . 1.2 描述了两种测试方法，如下所示: 部分 试验方法A——直接传动 试验方法B-后向散射 8. 9 1.3 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不一定是完全相等的；因此，为了确保符合标准，每个系统应独立使用，并且不得将两个系统的值组合使用。 1.4 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。 1.5 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 这些试验方法可作为现场测定未硬化混凝土密度的快速无损技术。反向散射测试方法也适用于硬化混凝土的相同目的。 测试方法固有的基本假设是康普顿散射是主要的相互作用，并且被测材料是均匀的。 4.2 这些测试方法适用于控制和协助施工期间的验收测试，用于施工后混凝土质量的评估，以及用于研究和开发。 注1: 在使用这些试验方法监测固结度时必须小心，固结度是特定混凝土实现的实际密度与可达到的最大密度的比值。这里介绍的测试方法用于确定实际密度。通过任何测试方法进行的密度测量都是混凝土成分的函数，并且在一定程度上可能会因这些成分的正常可接受变化而变化。 4.3 试验结果可能受到钢筋、混凝土成分的化学成分和样品不均匀性的影响。通过仪器设计和用户遵守测试程序的适当章节，将这些影响产生的变化降至最低。反向散射测试方法的测试结果也可能受到底层材料密度的影响。反向散射测试方法表现出空间偏差，因为仪器对其下材料的灵敏度随着距离混凝土表面的距离而降低。 注2: 通常，反向散射计读数表示顶部75中的密度 毫米至100毫米[3] 英寸至4英寸]的材料。

1.1 These test methods cover the determination of the in-place density of unhardened and hardened concrete, including roller compacted concrete, by gamma radiation. For notes on the nuclear test see Appendix X1 . 1.2 Two test methods are described, as follows: Section Test Method A—Direct Transmission Test Method B—Backscatter 8 9 1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined. 1.4 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. 1.5 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 These test methods are useful as rapid, nondestructive techniques for the in-place determination of the density of unhardened concrete. The backscatter test method is also useful for the same purpose on hardened concrete. The fundamental assumptions inherent in the test methods are that Compton scattering is the dominant interaction and that the material under test is homogeneous. 4.2 These test methods are suitable for control and for assisting in acceptance testing during construction, for evaluation of concrete quality subsequent to construction, and for research and development. Note 1: Care must be taken when using these test methods in monitoring the degree of consolidation, which is the ratio of the actual density achieved to the maximum density attainable with a particular concrete. The test methods presented here are used to determine the actual density. A density measurement, by any test method, is a function of the components of the concrete and may vary, to some extent, in response to the normal, acceptable variability of those components. 4.3 Test results may be affected by reinforcing steel, by the chemical composition of concrete constituents, and by sample heterogeneity. The variations resulting from these influences are minimized by instrument design and by the user's compliance with appropriate sections of the test procedure. Results of tests by the backscatter test method may also be affected by the density of underlying material. The backscatter test method exhibits spatial bias in that the apparatus's sensitivity to the material under it decreases with distance from the surface of the concrete. Note 2: Typically, backscatter gauge readings represent the density in the top 75 mm to 100 mm [3 in. to 4 in.] of material.