1.1 本试验方法涵盖了使用冲击回波法测定混凝土板、路面、桥面、墙壁或其他板状结构厚度的程序。 1.2 本试验方法包括以下两个程序: 1.2.1 程序A:P波速度测量- 该程序测量短时间点冲击产生的P波在沿结构表面相距已知距离的两个传感器之间传播所需的时间。通过将两个传感器之间的距离除以行程时间来计算P波速度。 1.2.2 程序B:冲击回波测试- 该程序测量短时间点冲击产生的P波在板平行（相对）表面之间反射的频率。根据该测量频率和从程序A获得的P波速度计算厚度。 1.2.3 除非另有规定，否则必须在进行厚度测定的每个点执行程序A和程序B。 1.3 以国际单位制表示的数值应视为标准值。 本标准不包括其他计量单位。 1.4 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。 1.5 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====== 4.1 本试验方法可代替取芯，或与取芯一起使用，以确定板、路面、桥面、墙壁或其他板结构的厚度。 由于所用数字记录的离散性，计算厚度中存在一定程度的系统误差。绝对系统误差取决于板厚、采样间隔和采样周期。 4.2 由于混凝土龄期或批次可变性的差异，结构中的波速可能会因点对点而异，因此在需要确定厚度（程序B）的每个点处测量波速（程序A）。 4. 3. 本试验方法适用于横向尺寸至少为厚度六倍的板状结构。这些最小横向尺寸对于防止其他模式是必要的 3. 振动干扰振幅谱中厚度模式频率的识别。如中所述 附注12 ，最小横向尺寸和可接受的采样周期相关。 4.4 可测量的最大和最小厚度受测试设备细节（传感器响应特性和特定冲击器）的限制。 限值应由仪器制造商规定，且仪器的使用不得超过这些限值。如果测试设备由用户组装，则应确定并记录厚度限制。 4.5 本试验方法不适用于具有覆盖层的板结构，例如具有沥青或波特兰水泥混凝土覆盖层的混凝土桥面。该方法基于以下假设:混凝土板在其整个深度内具有相同的纵波速度。 4.6 在空气干燥的混凝土上执行步骤A，因为高表面含水量可能会影响结果。 4.7 程序B适用于位于土壤、砾石、渗透性沥青混凝土或贫硅酸盐水泥混凝土路基上的混凝土板，前提是声阻抗存在足够的差异 3. 在混凝土和路基之间，或在界面处有足够的空隙，以产生可测量的反射。如果不满足这些条件，波形将为低振幅，振幅谱将不包括与厚度对应的频率处的主峰( 公式2 ). 如果混凝土和路基之间的界面粗糙，振幅谱将具有圆形峰值，而不是与平坦表面相关的尖锐峰值。 4.8 所述程序不受交通噪声或通过结构正常移动产生的低频结构振动的影响。 4.9 这些程序不适用于设备撞击结构（千斤顶锤、锤击、机械清扫器等）产生的机械噪声。 4.10 程序A不适用于存在高振幅电噪声的情况，例如可能由发电机或其他一些源产生的噪声，这些噪声被传输到数据采集系统。

1.1 This test method covers procedures for determining the thickness of concrete slabs, pavements, bridge decks, walls, or other plate-like structure using the impact-echo method. 1.2 The following two procedures are covered in this test method: 1.2.1 Procedure A: P-Wave Speed Measurement— This procedure measures the time it takes for the P-wave generated by a short-duration, point impact to travel between two transducers positioned a known distance apart along the surface of a structure. The P-wave speed is calculated by dividing the distance between the two transducers by the travel time. 1.2.2 Procedure B: Impact-Echo Test— This procedure measures the frequency at which the P-wave generated by a short-duration, point impact is reflected between the parallel (opposite) surfaces of a plate. The thickness is calculated from this measured frequency and the P-wave speed obtained from Procedure A. 1.2.3 Unless specified otherwise, both Procedure A and Procedure B must be performed at each point where a thickness determination is made. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of 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, 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 ====== 4.1 This test method may be used as a substitute for, or in conjunction with, coring to determine the thickness of slabs, pavements, decks, walls, or other plate structures. There is a certain level of systematic error in the calculated thickness due to the discrete nature of the digital records that are used. The absolute systematic error depends on the plate thickness, the sampling interval, and the sampling period. 4.2 Because the wave speed can vary from point-to-point in the structure due to differences in concrete age or batch-to-batch variability, the wave speed is measured (Procedure A) at each point where a thickness determination (Procedure B) is required. 4.3 This test method is a pplicable to plate-like structures with lateral dimensions at least six times the thickness. These minimum lateral dimensions are necessary to prevent other modes 3 of vibration from interfering with the identification of the thickness mode frequency in the amplitude spectrum. As explained in Note 12 , the minimum lateral dimensions and acceptable sampling period are related. 4.4 The maximum and minimum thickness that can be measured is limited by the details of the testing apparatus (transducer response characteristics and the specific impactor). The limits shall be specified by manufacturer of the apparatus, and the apparatus shall not be used beyond these limits. If test equipment is assembled by the user, thickness limitations shall be established and documented. 4.5 This test method is not applicable to plate structures with overlays, such as a concrete bridge deck with an asphalt or portland cement concrete overlay. The method is based on the assumption that the concrete plate has the same P-wave speed throughout its depth. 4.6 Procedure A is performed on concrete that is air dry as high surface moisture content may affect the results. 4.7 Procedure B is applicable to a concrete plate resting on a subgrade of soil, gravel, permeable asphalt concrete, or lean portland cement concrete provided there is sufficient difference in acoustic impedance 3 between the concrete and subgrade or there are enough air voids at the interface to produce measurable reflections. If these conditions are not satisfied, the waveform will be of low amplitude and the amplitude spectrum will not include a dominant peak at the frequency corresponding to the thickness ( Eq 2 ). If the interface between the concrete and subgrade is rough, the amplitude spectrum will have a rounded peak instead of a sharp peak associated with a flat surface. 4.8 The procedures described are not influenced by traffic noise or low frequency structural vibrations set up by normal movement of traffic across a structure. 4.9 The procedures are not applicable in the presence of mechanical noise created by equipment impacting (jack hammers, sounding with a hammer, mechanical sweepers, and so forth) on the structure. 4.10 Procedure A is not applicable in the presence of high amplitude electrical noise, such as may produced by a generator or some other source, that is transmitted to the data-acquisition system.