1.1 这些试验方法包括通过γ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，请参见 附录X1 . 1.2 描述了两种试验方法，如下所示: 部分 试验方法A-直接传输 试验方法B-反向散射 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值。每个系统中规定的值可能不是精确的等效值；因此，每个系统应相互独立使用。将两个系统的值合并可能会导致不符合标准。 1.4 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。 ====意义和用途====== 4.1 这些试验方法可作为快速、无损技术用于现场测定未硬化混凝土的密度。背散射试验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，并且测试材料是均匀的。 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、施工后的混凝土质量评估以及研发。 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达到的实际密度与可达到的最大密度之比。此处提供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，并且可能在一定程度上随这些成分的正常可接受变化而变化。 4.3 试验结果可能受钢筋、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部分，将这些影响引起的变化降至最低。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。背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与混凝土表面的距离而降低。 注2: 通常，后向散射计读数表示顶部75至100 mm[3至4 in]的密度材料。

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 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. 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 and health practices and determine the applicability of regulatory limitations prior to use. ====== 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 to 100 mm [3 to 4 in.] of material.