1.1 本试验方法提供了一种确定疲劳曲线的程序，该曲线是使用三个或更多应变水平绘制的。所得数据可用于机械经验路面设计（即路面ME）的疲劳模型。确定失效点以估计380的疲劳寿命 mm长x 50 mm厚×63 从实验室或现场压实的沥青混合料上锯下的宽度（宽度）为mm的沥青混合料梁（矩形棱柱）试样，其承受反复弯曲。 1.2 梁建议的最大标称最大骨料粒径（NMAS）50 mm厚为19 毫米。NMAS大于19的梁 mm可能会显著干扰材料响应，从而影响测试的重复性。 1.3 本标准的文本引用了提供解释材料的注释和脚注。这些注释和脚注（不包括表和图中的注释和脚注）不应视为本标准的要求。 1.4 单位- 以国际单位制表示的数值应视为标准值。本标准中不包括其他测量单位，但角度（°）除外，其中角度是根据 IEEE/ASTM SI 10 . 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、健康和环境实践，并确定监管限制的适用性。 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》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 本标准确定的梁试件实验室疲劳寿命已用于估算重复交通荷载下沥青混合料路面层的疲劳寿命。尽管沥青混合料的现场性能受到许多因素（交通变化、加载速率和漂移；气候变化；荷载之间的休息期；老化等）的影响，但当已知实验室特性以及在路面上行驶的交通轮荷载在层深诱导的应变水平估计时，可以更准确地预测沥青混合料的现场性能。 注2: 本标准产生的结果质量取决于执行程序的人员的能力以及所用设备的能力、校准和维护。 符合规范标准的机构 D3666 通常认为能够胜任和客观的测试、抽样、检查等。本标准的用户应注意遵守规范 D3666 单独使用并不能完全确保可靠的结果。可靠的结果取决于许多因素；遵循规范建议 D3666 或一些类似的可接受指南提供了评估和控制其中一些因素的方法。

1.1 This test method provides a procedure for determining a fatigue curve that is developed using three or more strain levels. The resulting data can be used in the fatigue models for mechanistic-empirical pavement design (that is, Pavement ME). Failure points are determined for estimating the fatigue life of 380 mm long by 50 mm thick by 63 mm in breadth (width) asphalt mixture beam (rectangular prism) specimens sawed from laboratory or field-compacted asphalt mixture, which are subjected to repeated flexural bending. 1.2 The largest nominal maximum aggregate size (NMAS) recommended for beams 50 mm thick is 19 mm. Beams made with an NMAS greater than 19 mm might significantly interfere with the material response, thereby affecting the repeatability of the test. 1.3 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the standard. 1.4 Units— The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard, with the exception of degrees (°) where angle is specified in accordance with IEEE/ASTM SI 10 . 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. 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 ====== 5.1 The laboratory fatigue life determined by this standard for beam specimens has been used to estimate the fatigue life of asphalt mixture pavement layers under repeated traffic loading. Although the field performance of asphalt mixtures is impacted by many factors (traffic variation, loading rate, and wander; climate variation; rest periods between loads; aging; etc.), it has been more accurately predicted when laboratory properties are known along with an estimate of the strain level induced at the layer depth by the traffic wheel load traveling over the pavement. Note 2: The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone does not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.