1.1本试验方法涵盖了使用弹簧驱动钢锤（也称为回弹锤、冲击试验锤或混凝土试验锤）测定岩石材料回弹硬度值的试验装置、取样、试样制备和试验程序。 1.2本试验方法最适用于单轴抗压强度（见试验方法D 7012）在约1至100 MPa之间的岩石材料。 1.3便携式测试仪器可在实验室或现场使用，以提供快速评估岩石硬度的方法或用作岩石硬度的指示器。 1.4以国际单位制表示的数值应视为标准。 1.5 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====== 回弹硬度法提供了一种在工程、设计和施工现场表征期间快速分类岩石硬度的方法（见指南D 420） )，岩石中大型地下开口的岩土工程制图（见指南D 4879） )或报告岩芯的物理描述（见实施规程D 4543 ). 回弹硬度值， H r ，可用于需要表征岩石材料的各种工程应用。例如，这些应用包括预测隧道掘进机的贯入率、确定施工用岩石质量以及预测岩石的水力侵蚀性。 本试验方法在极软岩石或极硬岩石（无侧限抗压强度小于约1 MPa或大于100 MPa）上的使用有限。 本试验方法的结果不用于转换为适合设计的强度数据。 笔记 1-市面上可以买到几种类型的回弹锤，以适应各种尺寸和类型的混凝土结构的测试（见测试方法C 805） )和岩石材料。 笔记 2-本标准产生的结果的质量取决于执行该标准的人员的能力，以及所用设备和设施的适用性。符合实践D 3740标准的机构 通常认为能够胜任客观的测试和采样。 本标准的用户应注意遵守实施规程D 3740 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D 3740 提供了一种评估其中一些因素的方法。

1.1 This test method covers the testing apparatus, sampling, test specimen preparation, and testing procedures for determining the rebound hardness number of rock material using a spring-driven steel hammer, referred to variously as a rebound hammer, impact test hammer, or concrete test hammer. 1.2 This test method is best suited for rock material with uniaxial compressive strengths (see Test Method D 7012) ranging between approximately 1 and 100 MPa. 1.3 The portable testing apparatus may be used in the laboratory or field to provide a means of rapid assessment of rock hardness or to serve as an indicator of rock hardness. 1.4 The values stated in SI units are to be regarded as the standard. 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 and health practices and determine the applicability of regulatory limitations prior to use. ====== Significance And Use ====== The rebound hardness method provides a means for rapid classification of the hardness of rock during site characterization for engineering, design, and construction purposes (see Guide D 420 ), geotechnical mapping of large underground openings in rock (see Guide D 4879 ), or reporting the physical description of rock core (see Practice D 4543 ). The rebound hardness number, H r , can serve in a variety of engineering applications that require characterization of rock material. These applications include, for examples, the prediction of penetration rates for tunnel boring machines, determination of rock quality for construction purposes, and prediction of hydraulic erodibility of rock. This test method is of limited use on very soft rock or very hard rock (unconfined compressive strengths less than approximately 1 MPa or greater than 100 MPa). The results of this test method are not intended for conversion to strength data suitable for design. Note 1—Several types of rebound hammers are commercially available to accommodate testing of various sizes and types of concrete construction (See Test Method C 805 ) and rock material. Note 2—The quality of the result produced by this standard 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 D 3740 are generally considered capable of competent and objective testing and sampling. Users of this standard are cautioned that compliance with Practice D 3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D 3740 provides a means of evaluating some of those factors.