ASTM C639-15 (R2020) PDF Download

The ASTM C639-15 (R2020) standard is a laboratory procedure used to determine the flow properties of single- and multi-component sealants used in building construction. The test measures the degree of horizontal or vertical flow of sealants when applied to a joint configuration at two predetermined temperatures. It is important to note that only samples conditioned at the same temperature can be directly compared.

The standard recognizes that sealants can have different rheological properties, ranging from pourable fluids to stiff non-sagging pastes. Multi-component sealants are supplied as two separate components, a base component, and an activator or curing agent, while single-component sealants are ready for use upon opening the package and rely on the external environment for cure.

The test method describes four types of joint sealants: Type I (single-component flowable or self-leveling), Type II (single-component non-sag), Type III (multi-component flowable or self-leveling), and Type IV (multi-component non-sag). It also mentions that special non-sag properties and lower flow characteristics may be required for use in sloping joints where absolute leveling is not desired.