Accelerated durability testing method

Durability test methods lack standardization and are not always representative of realistic service conditions it is therefore essential to develop standard accelerated ageing tests that correspond to actual in-situ environments. In particular, significant effort should be undertaken to study the synergistic effects between environmental factors (moisture, temperature, alkalinity, chemical attacks) and mechanical loads (sustained loads, fatigue) at both the material and structural scales. 

As an accelerated testing method, the OCV hold test plays an important role in accelerated durability tests [13-18]. The OCV hold test is believed to accelerate the chemical degradation of the membrane, which results in higher gas... 

Table 1 Surface energies (by the Owens-Wendt method) of two different SIGRACET gas diffusion layer (GDL) types before and after accelerated durability testing (different catalyst-coated membranes were used in the cells)...

Test Methods. Tests for water repeUency of concrete and masonry have been described by several authors (72,94). The National Bureau of Standards (NBS) evaluated fifty-five clear water repeUents for masonry surfaces (95). Performance tests included water absorption, water-vapor transmission, resistance to efflorescence, change in appearance, and durability to accelerated and outdoor weathering. More recently, the National Cooperative Highway Research Program conducted a study of several organic and sihcone water-repeUent treatments. The results are communicated in Report 244 (96). The testing procedure used in this study is now a popular method for evaluating water-repeUent treatments on concrete. 

Testing. Three replicate panels were made for each experimental point and properties were measured, in general, according to ASTM D-1037-72. One slight deviation was in the durability, or accelerated aging test. The ASTM method calls for the following ... 

Devalapura, R. K., M. E. Greenwood, J. V. Gauchel and T. J. Humphrey (1998). Evaluation of GERP performance using accelerated test methods. First International Conference on Durability of Fiber Reinforced Polymer Composites for Construction, Sherbrooke, Quebec, Canada, pp. 107-116. 

It has been shown that an accelerated test method (the automatic boil test—ASTM D-3434) is convenient for evaluating adhesive performance and for predicting durability for exterior applications. Samples are subjected to 800 cycles, which corresponds to approximately 16 years of exterior exposure for a good wood adhesive. Figure 6 compares the perform-... 

The objective of durability testing is to be able to predict the performance of an actual bonded structure on exposure to normal service conditions, based on the observed behavior of test specimens in accelerated laboratory procedures. Except in a few special cases, this is not possible at present. A number of methods, based on reaction rate theory and statistical approaches, show some progress, but, in general, satisfactory predictive methods have yet to be developed. This is important for the future use of structural adhesives, since the ability to predict performance will increase confidence in the use of structural adhesives as a viable joining method. 

TGSting. No test is available that reliably predicts the exterior durability of coatings, partly due to the wide variety of environments and application conditions (see Weathering). The limitations of accelerated tests, the need for data based on actual field experience, and methods of building a database are described in Reference 23. Use of reliability theory using statistical distribution functions of material, process, and exposure parameters for predicting exterior durability of automotive coatings has been recommended (46). Reference 55 reviews various test methods. 

Test methods Standardization of test methods Relation between properties of specimens and of a material in a structure Testing of structures in natural scale Accelerated test methods and evaluation of durability New test methods computer image analysis, tomography, micro-indentation, etc. 

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