1.1 本试验方法包括通过观察混凝土体积随压力变化的变化来测定新拌混凝土的空气含量。 1.2 本试验方法适用于由相对致密骨料制成的混凝土和砂浆，其骨料修正系数可通过第节所述技术令人满意地确定 6 不适用于轻质骨料、风冷高炉矿渣或高孔隙率骨料制成的混凝土。在这些情况下，测试方法 C173/C173M 应该使用。该测试方法也不适用于非塑性混凝土，例如通常用于制造管道和混凝土砌体单元的非塑性混凝土。 1.3 本试验方法的正文参考了提供解释性信息的注释和脚注。这些注释和脚注（不包括表格和图表中的注释和脚注）不应被视为本标准的要求。 1.4 以SI单位或英寸-磅单位表示的值应单独视为标准值。每个系统中陈述的值不一定完全等同；因此，为确保符合标准，每个系统应独立使用，两个系统的数值不得合并使用。 附注1: 筛子尺寸由其在质量标准中的标准名称标识 E11 括号中给出的替代名称仅供参考，并不代表不同的标准筛尺寸。 1.5 本标准并不旨在解决与其使用相关的所有安全性问题（如果有）。本标准的使用者有责任在使用前建立适当的安全、健康和环境实践并确定法规限制的适用性。( 警告- 新鲜的水硬性水泥混合物是腐蚀性的，长时间接触可能会对皮肤和组织造成化学灼伤。 2 ) 1.6 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》中确立的国际公认的标准化原则制定的。 ======意义和用途====== 3.1 本试验方法包括新拌混凝土空气含量的测定。该测试确定新拌混凝土的空气含量，不包括骨料颗粒空隙内可能存在的任何空气。因此，它适用于由相对致密的骨料颗粒制成的混凝土，并需要确定骨料修正系数（见 6.1 和 9.1 ). 3.2 本试验方法和试验方法 C138/C138M 和 C173/C173M 分别提供压力、重量和体积程序，用于确定新拌混凝土的空气含量。对于用致密骨料制成的混凝土，该试验方法的压力程序给出的空气含量与其他两种试验方法基本相同。 3.3 硬化混凝土的空气含量可能高于或低于本试验方法测定的空气含量。这取决于施加到取硬化混凝土试样的混凝土上的固结力的方法和量；新拌和硬化混凝土中气泡的均匀性和稳定性；显微镜检查的准确性（如果使用）；比较时间；环境暴露；在输送、放置和固结过程中确定未硬化混凝土的空气含量的阶段，即在混凝土通过泵之前或之后；等因素。

1.1 This test method covers determination of the air content of freshly mixed concrete from observation of the change in volume of concrete with a change in pressure. 1.2 This test method is intended for use with concretes and mortars made with relatively dense aggregates for which the aggregate correction factor can be satisfactorily determined by the technique described in Section 6 . It is not applicable to concretes made with lightweight aggregates, air-cooled blast-furnace slag, or aggregates of high porosity. In these cases, Test Method C173/C173M should be used. This test method is also not applicable to nonplastic concrete such as is commonly used in the manufacture of pipe and concrete masonry units. 1.3 The text of this test method references notes and footnotes that provide explanatory information. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of this standard. 1.4 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. Note 1: Sieve size is identified by its standard designation in Specification E11 . The alternative designation given in parentheses is for information only and does not represent a different standard sieve size. 1.5 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. ( Warning— Fresh hydraulic cementitious mixtures are caustic and may cause chemical burns to skin and tissue upon prolonged exposure. 2 ) 1.6 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 ====== 3.1 This test method covers the determination of the air content of freshly mixed concrete. The test determines the air content of freshly mixed concrete exclusive of any air that may exist inside voids within aggregate particles. For this reason, it is applicable to concrete made with relatively dense aggregate particles and requires determination of the aggregate correction factor (see 6.1 and 9.1 ). 3.2 This test method and Test Method C138/C138M and C173/C173M provide pressure, gravimetric, and volumetric procedures, respectively, for determining the air content of freshly mixed concrete. The pressure procedure of this test method gives substantially the same air contents as the other two test methods for concretes made with dense aggregates. 3.3 The air content of hardened concrete may be either higher or lower than that determined by this test method. This depends upon the methods and amount of consolidation effort applied to the concrete from which the hardened concrete specimen is taken; uniformity and stability of the air bubbles in the fresh and hardened concrete; accuracy of the microscopic examination, if used; time of comparison; environmental exposure; stage in the delivery, placement and consolidation processes at which the air content of the unhardened concrete is determined, that is, before or after the concrete goes through a pump; and other factors.