ASTM C792-15(R2020) pdf free download

ASTM C792-15(R2020) pdf free download.Standard Test Method for Effects of Heat Aging on Weight Loss, Cracking, and Chalking of Elastomeric Sealants
1. Scope
1.1 This test method covers a laboratory procedure for determining the effects of heat aging on weight loss, cracking, and chalking of cured-in-place elastomeric joint sealants (single- and multi-component) for use in building construction. 1.2 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. 1.3 There is no known ISO equivalent to this test method. 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.
5. Significance and Use
5.1 Weight loss through volatilization of components of a sealant in a building joint may affect sealant appearance because of shrinkage and sealant performance because of the loss of functional sealant components. Exposure to high- temperature environments will accelerate the loss of volatiles. 5.2 This test method measures weight loss. It can be used in combination with a knowledge of sealant density to estimate shrinkage. In addition, when compared to sealant theoretical weight solids, it provides an estimate of the extent to which functional sealant components can be volatilized when exposed to high service temperatures. Substantial losses of this type may help predict early failures in durability. Also, development of cracks or chalking, or both, lessens sealant service life. However, a sealant that develops no cracks or chalking, or low weight loss in this test method, does not necessarily assure good durability.
7. Procedure
7.1 Unless otherwise specified by those authorizing the test, standard conditions of temperature and relative humidity for the test shall be found in Terminology C717. 7.2 Test ofMulticomponent Sealants: 7.2.1 Condition at least 400 g of base compound and appropriate amount of curing agent in a closed container for at least 24 h at standard conditions; then mix thoroughly for 5 min. 7.2.2 Weigh the three aluminum plates to the nearest 0.01 g. 7.2.3 Fill the rectangular frame, after centering it on an aluminum plate, with a portion of the conditioned compound, and strike it off flat with a straightedge. Immediately lift the frame from the sealant after separating it by running a thin-bladed knife along the inside of the frame (Note 1). Prepare three such specimens, weigh each to the nearest 0.01 g, and cure them for 7 days at standard conditions. 7.2.4 Following the 7-day curing period, place two of the three specimens in the draft oven for 21 days, leaving the third (control) specimen at standard conditions for the same period. 7.2.5 At the end ofthe 21-day period, remove the specimens from the oven and allow to cool for 1 h at standard conditions. Weigh them to the nearest 0.01 g and calculate the percent weight loss of the sealants as follows:7.2.6 Examine the sealants for cracking and chalking and compare with the third (control) specimen. N OTE 1—In the case of a pourable grade compound, do not lift the rectangular frame until the sealant is sufficiently set that it will retain its rectangular shape. 7.3 Test ofSingle-Component Sealants: 7.3.1 Condition at least 400 g of compound in a closed container for at least 24 h at standard conditions. 7.3.2 Follow the same procedure as specified in 7.2.1 – 7.2.6, eliminating the mixing necessary for multicomponent sealants.