ASTM C1735-17(R2021) pdf free download

ASTM C1735-17(R2021) pdf free download.Standard Test Method for Measuring the Time Dependent Modulus of Sealants Using Stress Relaxation
1. Scope
1.1 This test method covers a procedure for measuring the time dependence of modulus in elastomeric joint sealants in a test specimen configuration described in Test Method C719. These sealant materials are typified by highly filled rubber materials. Any Mullins effect is first assessed and mitigated in two loading-unloading cycles. Time dependence of modulus in materials is then determined using a stress relaxation proce- dure. 1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard. 1.3 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.4 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
4. Summary of Test Method
4.1 This test method consists of two loading cycles where strain is increased from a 0 % to a user-defined maximum strain and one stress relaxation procedure at a strain no greater than 2 ⁄ 3 of the user-defined maximum strain. A schematic diagram of this test strain history is shown in Fig. 1. 4.2 The motivation for the two loading-unloading cycles is to assess if any Mullins effect is present and to mitigate any of this effect in the subsequent stress relaxation test. As long as the maximum strain achieved during the first deformation is not exceeded, however, all subsequent loadings follow the same stress-strain curve. 4.3 Stress relaxation procedure is based on a sudden impo- sition of either a tensile or compressive strain on the test specimen at a value of no more than 2 ⁄ 3 of the maximum strain and the measurement of the load required to maintain this tensile or compressive strain as a function of time. 4.4 The conversion of load relaxation values to apparent modulus and fractional change in apparent modulus is accom- plished by inputting information about the specimen geometry and the amount ofdeformation into an equation that is based on the statistical theory of rubber-like elasticity.
5. Significance and Use
5.1 The intent of this test method is to determine the time dependence of modulus in building joint sealants using two loading-unloading cycles to identify and mitigate any Mullins effect, and followed by a stress relaxation procedure to determine the time dependent modulus. 5.2 This test method has found applications in screening the performance ofbuilding joint sealants since the modulus is one indicator of the ability of elastomeric building sealant to withstand environmental induced movements.
6. Apparatus
6.1 Testing Machine—Any testing machine in compliance with Practices E4, capable of producing a constant crosshead displacement rate in displacement control and equipped with means for recording complete load versus displacement curves during the test. 6.2 Load Cell—The load cell of the testing machine shall be capable of recording the load with an accuracy of 61 % of the maximum indicated value. 6.3 Loading Fixtures—Used to mount specimens to the testing machine so that the surface of the substrate is perpen- dicular to the direction ofthe applied load and to minimize any eccentric loading in the test specimen. 6.4 Air-circulating Oven—To condition specimens at the specific temperature and relative humidity. 6.5 Mechanical Fastener or Rubber Bands—To hold a specimen assembly together before and after filling it with sealant compound. 6.6 Geometry Measuring Tool—To measure the dimensions ofaluminum substrate and sealant to an accuracy ofat least 65 mm (0.2 in.). Because stress is the load per area exerted on the test specimen, an accurate measurement of the geometry is critical.
7. Preparation of Test Specimen
7.1 Test conditions of temperature and relative humidity used throughout this test method are defined in Terminology C717. 7.2 The standard substrate used in the test shall be alumi- num alloy 76.2 by 12.7 by 12.7 mm (3 by 0.5 in. by 0.5 in.), 6063-T5, or 6061-T6 with anodizing process AA- M10C22A31.