ASTM C920 Standard Specification for Elastomeric Joint Sealants

Get Certified ASTM C920 Testing for Reliable Elastomeric Joint Sealants

Joint sealants must be flexible and adhere to the joint surfaces as they move during service. Thus, the standardized testing can be used by manufacturers and engineers to decide if a sealant will function under the conditions of its intended application. ASTM C920 (Standard Specification for Elastomeric Joint Sealants) sets requirements for elastomeric sealants and test procedures for determining key physical and performance properties. These results can be used for product development, quality control, materials comparison, and construction.

• Sets requirements for an elastomeric joint sealant.
• Deals with sealants in building construction.
• Classifies sealants according to type, grade, class, and use.
• Assesses glue and stick characteristics.
• Assesses movement capacity and recovery.
• This helps to assess the durability of sealants.
• Describes the requirements of various service conditions.
• Ensures manufacturers can maintain the quality of their sealant.

What are the Uses of ASTM C920 Testing?

ASTM C920 testing helps laboratories to assess elastomeric joint sealants to specification requirements. The results are used by engineers to evaluate the performance of the sealant and to identify whether it is suitable for a particular joint application. This standard-

• Evaluates sealant adhesion.
• Measures tensile properties.
• Determines hardness.
• Assesses extension and recovery.
• Assesses adhesion in peel.
• This assists in the assessment of movement capabilities.
• Assists in comparing sealant formulations.
• Assists with product development and quality control.

Which materials can be tested under ASTM C920?

ASTM C920 covers elastomeric joint sealants used in building construction and allied sealing applications. These products may contain sealants using various polymer systems that comply with the classification and performance requirements. Before selecting the required tests, laboratories should know the sealant type, intended use, grade, class, and specification requirements.

Why is ASTM C920 Important?

ASTM C920 sets standard requirements for elastomeric joint sealants for use in construction. Regular testing can help manufacturers and engineers determine if sealants will adhere, be flexible, and have the other necessary characteristics throughout the service life. The findings also aid in the choice of appropriate sealants for joints that are subject to movement, weathering, moisture, and other environmental factors.

ASTM C920 Testing Process and Data Collection

The sealant formulation is identified, and the ASTM C920 classification and test requirements are determined. Later, the specimens are prepared, and the sealant is applied to the necessary substrates or molds. Then the specimens are conditioned as needed and subjected to the appropriate adhesion, tensile, hardness, extension, recovery, or other performance tests. The system for testing records the necessary measurements and observations. Lastly, the measured properties are compared to ASTM C920 requirements. Laboratories present the results along with the sealant identification and test conditions.

Common Challenges and Troubleshooting

Proper specimen preparation, substrate selection, conditioning, and controlled testing are required to obtain accurate ASTM C920 results. Application and curing conditions can vary and influence adhesion and mechanical measurements. The size of the specimen and the curing conditions should be checked by the technicians prior to testing. Reliable results of sealant performance can also be achieved by proper substrate preparation and conditioning.

• The ASTM C920 results are property-specific and not an overall test value.
• Tensile properties may be expressed in either MPa or psi.
• Hardness can be expressed on an appropriate hardness scale.
• Extension and movement ability can be expressed as a percentage.
• Depending on the procedure, adhesion results can be given as stress values or observed adhesion-failure characteristics.
• Laboratories are able to generate reliable results if specimens are prepared in the same way and are subjected to the same conditioning.

Link to ASTM C920