For walls or other areas not subject to physical wear. Substrate-Specific Uses: M: Mortar/Masonry G: Glass A: Aluminum I: Continuous Immersion (like pools or fountains) Key Performance Testing Requirements
: For vertical wall joints or non-trafficked horizontal areas.
The ASTM C920 standard specifies the following key requirements for elastomeric joint sealants:
The standard provides a universal classification system—Type, Grade, Class, and Use—to help architects and contractors select the right product for specific applications like curtain walls, plaza decks, or window perimeters. For walls or other areas not subject to physical wear
: Measures bond strength to specific substrates.
: For pedestrian or vehicular traffic areas like plazas.
Architects and specifiers rely on ASTM C920 to ensure that a sealant will accommodate expected building movement, adhere to common substrates (concrete, glass, aluminum, etc.), and maintain a weathertight seal over a typical service life of 5–20 years, depending on the application. : Measures bond strength to specific substrates
: Evaluates the sealant's ability to maintain adhesion and cohesion during repeated expansion and contraction.
Every C920-compliant sealant is defined by four core categories:
: Specifies compatible substrates and environment conditions. : Evaluates the sealant's ability to maintain adhesion
Confirms the sealant won't "bleed" oils that could stain porous surfaces like white marble or limestone. Why It Matters
Requires mixing two or more parts before application. These often cure faster and are used for high-volume or specialized industrial projects. 2. Grade: Flow and Consistency
Also known as "self-leveling." These are designed for horizontal joints (like parking garage floors ) where the sealant flows to form a smooth surface.