Some concrete joint sealants fail prematurely because the person who selected those products didn't understand the language that the manufacturer used when describing the attributes of that product. This article discusses some of the key words that can help you to decide whether a given sealant will do a good job if you use it.
Elongation defines the degree to which a given concrete joint sealing product can stretch. This extent is normally given as a fraction/percentage of the dimensions of the sealer upon application. For example, a sealant with 50-percent elongation will stretch by half its size when the joint expands. You should therefore select a concrete joint sealant with a high elongation capacity in case you expect significant movements in the joints which you wish to seal.
The modulus of a concrete joint sealant refers to the magnitude of tensile forces that the sealant can withstand after it has reached a given elongation capacity. This modulus has an impact on how much the sealant is capable of stretching. For example, sealants with a high modulus tend to have low elongation since the sealant can resist the tensile forces that are being exerted upon it. Conversely, sealants with low modulus tend to stretch more since tensile forces have a greater impact upon them.
High modulus is a desirable sealant characteristic in applications where minimal joint movement is expected. High modulus concrete joint sealants are ideal for applications where the joint is likely to be exposed to abrasive forces. Such a sealant will resist being punctured better than a sealant with low modulus.
Performance with regard to concrete joint sealants refers to how well a given sealing product is capable of stretching and recovering to its original dimensions once a joint narrows. For example, a sealant can be described as a low-performance sealant if it is incapable of recovering once the joint moves beyond 5% of its width. Medium performance concrete joint sealants can recover after being stretched to a level that is larger than what low-performance sealants can take.
Similarly, high-performance sealants can handle more stretching than what medium-performance sealing products can. Read the product literature and confirm the product which you intend to use can recover after being stretched beyond the minimum percentage of the joint width that you anticipate.
It may not be possible for a layperson to decide the correct balance between modulus, elongation and performance when selecting a concrete joint sealant. Enlist the help of a professional so that you select a product that will not fail prematurely