1.1 本试验方法包括使用弹簧驱动钢锤测定硬化混凝土的回弹数。 1.2 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。 1.3 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、健康和环境实践，并确定监管限制的适用性。 1.4 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 本试验方法适用于评估混凝土的现场均匀性，描绘整个结构中混凝土质量的变化，并在根据以下标准建立相关性的情况下估计现场强度 5.4 . 5.2 对于给定的混凝土混合物，回弹数受测试表面的含水量、待测试表面施工中使用的模板材料类型或饰面类型、距混凝土浇筑底部的垂直距离和碳化深度等因素的影响。 在解释反弹数字时，需要考虑这些因素。 5.3 相同标称设计的不同仪器的回弹值可能不同于1到3个单位。因此，应使用相同的仪器进行测试，以比较结果。如果要使用多个仪器，请在一系列典型混凝土表面上进行比较测试，以确定不同仪器读数中预期差异的大小。 5.4 仪器制造商提供的回弹数和混凝土强度之间的关系只能用于指示结构中不同位置的相对混凝土强度。为了使用本试验方法估算强度，有必要建立给定混凝土和给定仪器的强度和回弹数之间的关系（见 注1 ). 通过将结构上测得的回弹数与从相应位置测得的岩芯强度相关联来建立关系（参见 注释2 ). 应从至少六个具有不同回弹数的位置取至少两个复制芯。选择测试位置，以便获得结构中广泛的回弹数。根据测试方法获取、制备和测试岩芯 C42/C42M . 如果回弹数受测试期间仪器方向的影响，则强度关系适用于用于获取相关日期的相同方向（参见 附注3 ). 使用发展的相关性估计强度的位置应具有类似的表面纹理，并应暴露在与取相关岩芯的位置类似的条件下。回弹锤的功能应根据 6.4 在进行相关性测量之前。 注1: 见ACI 228.1R 4. 或BS EN 13791，获取关于发展关系和使用关系进行估算的更多信息- 放置力量。 注2: 使用模制试样建立相关性可能无法提供可靠的关系，因为模制试样的表面纹理和碳化深度通常不能代表现浇混凝土。 注3: 如果相关性是针对与测试不同的方向开发的，则使用校正因子来解释仪器方向可能会降低强度估计的可靠性。 5.5 本试验方法不适合作为混凝土验收或拒收的依据。

1.1 This test method covers the determination of a rebound number of hardened concrete using a spring-driven steel hammer. 1.2 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. 1.3 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. 1.4 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 ====== 5.1 This test method is applicable to assess the in-place uniformity of concrete, to delineate variations in concrete quality throughout a structure, and to estimate in-place strength if a correlation is developed in accordance with 5.4 . 5.2 For a given concrete mixture, the rebound number is affected by factors such as moisture content of the test surface, the type of form material or type of finishing used in construction of the surface to be tested, vertical distance from the bottom of a concrete placement, and the depth of carbonation. These factors need to be considered in interpreting rebound numbers. 5.3 Different instruments of the same nominal design may give rebound numbers differing from 1 to 3 units. Therefore, tests should be made with the same instrument in order to compare results. If more than one instrument is to be used, perform comparative tests on a range of typical concrete surfaces so as to determine the magnitude of the differences to be expected in the readings of different instruments. 5.4 Relationships between rebound number and concrete strength that are provided by instrument manufacturers shall be used only to provide indications of relative concrete strength at different locations in a structure. To use this test method to estimate strength, it is necessary to establish a relationship between strength and rebound number for a given concrete and given apparatus (see Note 1 ). Establish the relationship by correlating rebound numbers measured on the structure with the measured strengths of cores taken from corresponding locations (see Note 2 ). At least two replicate cores shall be taken from at least six locations with different rebound numbers. Select test locations so that a wide range of rebound numbers in the structure is obtained. Obtain, prepare, and test cores in accordance with Test Method C42/C42M . If the rebound number is affected by the orientation of the instrument during testing, the strength relationship is applicable for the same orientation as used to obtain the correlation date (see Note 3 ). Locations where strengths are to be estimated using the developed correlation shall have similar surface texture and shall have been exposed to similar conditions as the locations where correlation cores were taken. The functionality of the rebound hammer shall have been verified in accordance with 6.4 before making the correlation measurements. Note 1: See ACI 228.1R 4 or BS EN 13791 for additional information on developing the relationship and on using the relationship to estimate in-place strength. Note 2: The use of molded test specimens to develop a correlation may not provide a reliable relationship because the surface texture and depth of carbonation of molded specimens are not usually representative of the in-place concrete. Note 3: The use of correction factors to account for instrument orientation may reduce the reliability of strength estimates if the correlation is developed for a different orientation than used for testing. 5.5 This test method is not suitable as the basis for acceptance or rejection of concrete.