ASTM C1851-18

5.1 The intent of this practice is to quantitatively determine the amount of cracking of a sealant relative to an unexposed or uncracked sample. Some samples of sealant have been observed to exhibit some degree of cracking some period after installation. The degree of cracking is assessed visually in a qualitative manner that takes into account the area of the cracks at the exposed surface of the sealant, but does not take into account the depth or profile of the cracks. The degree of cracking in the sealant has been used as an indication of performance change.

1.1 This practice covers a procedure for quantitatively determining the extent of cracking in a sealant sample by evaluating the difference between the measured compressive and tensile modulus of a sealant relative to an unexposed or uncracked version of the same sealant. The cracks will reduce the area of the sealant in the tensile modulus, but in the compressive modulus measurement they will not change the area over which the modulus is determined.

1.2 The values in SI units are to be regarded as standard. The values in parentheses are for information only.

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 appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 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.