1.1 本规程描述了室外暴露程序，作为测试的一部分，该测试旨在确定建筑结构、密封件和密封剂的耐候性。 注1: 参见练习 第24组 通过玻璃过滤的日光暴露。 1.2 本规程包括三个室外风化程序。程序A将试样暴露在室外风化条件下，不得移动。程序B和程序C分别是连续的自然和定期手动技术，用于使试样经受循环运动和暴露于室外风化的组合。 1.3 本规程仅限于将建筑密封件或密封剂暴露在室外风化条件下作为测试程序的一部分的方法。它指的是户外暴露后进行的评估类型，但未描述测试方法。 1.4 风化影响的评估方法取决于试验材料的预期用途。 1.5 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。每个系统中所述的值不一定完全相等；因此，为了确保符合标准，每个系统应独立使用，两个系统的值不得合并。 1.6 本标准并不旨在解决与其使用相关的所有安全问题（如有）。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，并确定监管限制的适用性。 1. 7. 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《国际标准、指南和建议制定原则决定》中确立的国际公认标准化原则制定的。 =====意义和用途====== 4.1 根据本规程进行的试验用于评估建筑密封和密封剂材料暴露在室外天气条件下的耐候性。由于太阳辐射、湿度、温度、污染物和其他因素的差异，密封件和密封剂在实际室外使用中的耐候性可能因位置而异。 密封剂颜色也可能影响耐候性。 4.2 该实践允许三种选择:选项1–程序A，其中不考虑风化过程中的移动影响；选项2–程序B，其中试样随热变化的移动而风化。施加的应变与设备安装时的温度和随后的热变化的组合成比例。该选项与许多密封剂安装中发生的实际运动非常相似，但其可重复性低于程序C中的运动；选项3–程序C，其中人工施加风化期间的应变。该程序可实现出色的控制和重复性，但与程序B中的运动相比，它在实际使用条件下的运动代表性较差。 根据同行评审的科学文献，本规程增加了选项2和选项3，这些文献表明，单独施加的应变以及其他风化应力会导致密封剂的耐候性发生变化。 4.3 密封剂的类型、频率和移动量因位置而异，可能会影响耐候性。因此，不能假设在一个地点进行一次暴露的结果将有助于确定不同地点的气候适应性。建议在不同气候（例如，太阳辐射、湿度、温度、污染物、生物和其他因素）的多个地点暴露，这些气候代表了广泛的预期使用条件。 4.4 强烈建议将成分和结构与试样相似且具有已知耐候性的对照材料与试样一起暴露，以比较试验材料与对照材料的性能。 （参见 6.2 ). 4.5 短期暴露试验的结果可以提供相对室外性能的指示，但不能用于预测密封或密封剂材料的绝对长期性能。不到12个月的测试结果将取决于开始测试的年份的特定季节。 4.6 由于每年的气候变化，单次暴露试验的结果不能用于预测密封件或密封剂降解的绝对速率。需要几年的重复暴露才能确定给定地点的平均测试结果。 4.7 气候和施工因素会对使用中的密封接头施加循环运动。这种运动会影响室外风化的影响，并经常导致不运动的风化所产生的破坏类型。 因此，建筑接缝密封剂承受温度引起的压缩和膨胀运动的能力是一个重要的特性。 4.8 在暴露过程中，试样的室外风化与自然或强制循环运动相结合，可以更真实地评估密封件或密封剂承受气候和建筑施工应用中密封件和密封剂所遇到的运动的综合影响的能力。

1.1 This practice describes outdoor exposure procedures to be used as part of a test designed to determine the weatherability of building construction, seals and sealants. Note 1: See Practice G24 for Exposures to Daylight Filtered Through Glass. 1.2 This practice includes three procedures for outdoor weathering. Procedure A exposes specimens to outdoor weathering without movement. Procedure B and Procedure C are, respectively, continuous natural and periodic manual techniques for subjecting specimens to the combination of cyclic movement and exposure to outdoor weathering. 1.3 This practice is limited to the method by which the construction seals or sealants are exposed to outdoor weathering as part of a test program. It refers to the types of evaluations to be performed following the outdoor exposure but does not describe the test methods. 1.4 Means of evaluation of the effects of weathering will depend on the intended use of the test material. 1.5 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. 1.6 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. 1.7 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 Tests conducted in accordance with this practice are used to evaluate the weatherability of construction seals and sealant materials when they are exposed to outdoor weather conditions. The weatherability of seals and sealants in actual outdoor use can be very different depending on the location because of differences in solar radiation, moisture, temperature, pollutants, and other factors. Sealant color may also affect weatherability. 4.2 This practice allows for three options: Option 1 – Procedure A in which the effect of movement during weathering is not considered; Option 2 – Procedure B in which specimens are weathered in conjunction with movement based on thermal changes. The applied strain is proportional to a combination of the temperature at the time the equipment is set up and subsequent thermal changes. This option closely mimics the actual movements that occur in many sealant installations, but is less repeatable than the movement in Procedure C; Option 3 – Procedure C in which the strain during weathering is manually applied. This procedure allows for excellent control and repeatability, but is less representative of movement in actual use conditions than the movement in Procedure B. Options 2 and 3 have been added to this practice based on peer reviewed scientific literature demonstrating that applied strain separately and in combination with other weathering stresses causes changes in the weatherability of sealants. 4.3 The type, frequency and amount of movement of sealants varies with location and may affect weatherability. It cannot be assumed, therefore, that results from one exposure in a single location will be useful for determining weatherability in a different location. Exposures in several locations with different climates (for example, solar radiation, moisture, temperature, pollutants, biological and other factors) that represent a broad range of anticipated service conditions are recommended. 4.4 It is strongly recommended that control materials of similar composition and construction to the test specimens and with known weatherability be exposed along with the test specimens for the purpose of comparing the performance of test materials to the controls. (See 6.2 ). 4.5 The results of short-term exposure tests can provide an indication of relative outdoor performance, but they shall not be used to predict the absolute long-term performance of a seal or sealant material. The results of tests conducted for less than 12 months will depend on the particular season of the year in which they begin. 4.6 Because of year-to-year climatatological variations, results from a single exposure test cannot be used to predict the absolute rate at which a seal or sealant degrades. Several years of repeat exposures are needed to determine an average test result for a given location. 4.7 Climatic and construction factors can impose cyclic movement upon sealed joints in use. This movement can impact the effects of outdoor weathering and often causes types of failure that are not produced by weathering without movement. Thus, the ability of building joint sealants to withstand temperature-induced movements of compression and expansion is an important property. 4.8 Outdoor weathering of specimens in combination with natural or forced cyclic movement during exposure can provide a more realistic assessment of the ability of a seal or sealant to withstand the combined effects of climate and movement encountered by seals and sealants in building construction applications.