Four Types of Sealant Joint Failure

Four Types of Sealant Joint Failure

There are four types of joint failure:

• adhesive
• cohesive
• substrate
• three-sided adhesion

ADHESIVE FAILURE

Adhesive failure occurs when the sealant loses adhesion to the sides of the joint. This can be caused by poor joint preparation, lack of required sealer, incorrect sealant selection, or by excessive joint movement.

COHESIVE FAILURE

Cohesive failure occurs when the sealant itself fails in its strength. This can be caused by aging sealant, improper mixing, or by joint movement beyond the ability of the sealant

 

SUBSTRATE FAILURE

Substrate failure occurs when the surface of the joint sides fail. This can be caused by weak substrate strength, tensile strength of sealant greater than tensile strength of substrate, or damage to joint sides by excessive load to joint area (example: heavy equipment rolled over a joint in a floor slab).

 

THREE SIDED ADHESION

It is most important that a sealant only adhere to the two sides of the joint and not the base of the joint (3rd side). Adhesion to all three sides will prevent the sealant from elongating properly and will cause sealant failure.