ASTM C792-15 (2020) pdf free.Standard Test Method for Effects of Heat Aging on Weight Loss, Cracking, andChalking of Elastomeric Sealants.
Unless otherwise specified by those authorizing the test,standard conditions of temperature and relative humidity forthe test shall be found in Terminology C717.
Test of Multicomponent Sealants:Condition at least 400 g of base compound andappropriate amount of curing agent in a closed container for atleast 24 h at standard conditions; then mix thoroughly for 5min. Weigh the three aluminum plates to the nearest 0.01 g.7.2.3 Fill the rectangular frame，after centering it on analuminum plate,with a portion of the conditioned compound,and strike it off flat with a straightedge. Immediately lift theframe from the sealant after separating it by running athin-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.Following the 7-day curing period, place two of thethree specimens in the draft oven for 21 days, leaving the third(control) specimen at standard conditions for the same period.
Report the following information for each sampletested:Identification of the sealant tested.Description of the type of sealant,such as single- ormulticomponent,nonsag or self-leveling, color,etc.Percent weight losses of the heat-treated specimens.8.1.4 Presence of cracking and chalking as compared withthe control specimen. Fig. 1 includes examples of crackingobtainable in this test. Number 0 represents no cracking.8.1.5 Variation, if any, from the specified test procedure.
A statistical analysis made from the results obtainedfrom a round-robin test in which each of three laboratoriestested seven sealant samples in accordance with the prescribedtest for effect of heat aging on weight loss resulted in thefollowing: Repeatability (that is，the difference between twodeterminations of weight loss on the same sample within thesame laboratory) was 0.51 % weight loss.Reproducibility (that is,the difference between theresults of two laboratories，each making two weight lossdeterminations on the same sample) was 0.90 %.The results obtained by the three laboratories in whicheach laboratory tested seven sealant samples in accordancewith the prescribed test for the effect of cracking and chalking were close to unanimous.The exception was the report of onelaboratory indicating no cracking or chalking of one sample,whereas the remaining two laboratories reported slight crack-ing and chalking.ASTM C792 pdf download.