【国外标准】 Standard Test Method for Evaluating Durability of Building Construction Sealants by Laboratory Accelerated Weathering Procedures

4.1 This test method describes the procedure to evaluate or compare, or both, the durability of sealants when subjected to accelerated weathering and cyclic movement in a joint.4.2 Sealant installation procedures, design considerations and movement during cure affect the aging processes and are fundamental to the success of any sealant. These factors are not addressed with this test method.4.3 The amount, type and frequency of movement a sealant experiences during its lifetime strongly depends on the materials used in construction and on the orientation of the joint toward sunlight and many other factors that are not uniform or consistent.4.4 Climatic exposures will differ with the orientation of the building and shading as well as with local and regional climatic conditions. Climates in a given location can vary from year to year because of differences in solar radiation, temperature, rainfall, and atmospheric conditions. Further, the quality and intensity of solar radiation on the earth's surface varies with geographic location, season, time of day, and cloud cover.4.5 Variations in results may be expected when operating conditions are varied within the accepted limits of this test method. Therefore, all test results using this test method must be accompanied by a report of the specific operating conditions as required in Section 11. Refer to Practice G151 for detailed information on the caveats applicable to use of results obtained according to this test method.4.6 The results of laboratory exposure cannot be directly extrapolated to estimate an absolute rate of deterioration caused by natural weathering because the acceleration factor is material dependent and can be significantly different for each material and for different formulations of the same material. However, exposure of a similar material of known outdoor performance, a control, along with the test specimens allows comparison of the durability relative to that of the control under the test conditions. Evaluation in terms of relative durability also greatly improves the agreement in test results among different laboratories.4.7 Results of this procedure will depend on the care that is taken to operate the equipment according to Practices G154 and G155. Significant factors include regulation of the line voltage, freedom from salt or other deposits from water, temperature control, humidity control, where applicable, condition and age of the burners and filters in xenon arc equipment, and age of lamps in fluorescent UV equipment.NOTE 1: Additional information on sources of variability and on strategies for addressing variability in the design, execution and data analysis of laboratory accelerated exposure tests is found in Guide G141.1.1 This test method covers the method for the determination of the durability of a sealant based on its ability to function in cyclic movement maintaining adhesion and cohesion after repeated exposure to laboratory accelerated weathering procedures.1.2 This test method describes two laboratory accelerated weathering procedures for evaluating the durability of a sealant.1.3 RILEM TC139–DBS is related to this test method.1.4 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.1.5 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.