Page 263 - Construction Waterproofing Handbook
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5.22 CHAPTER FIVE
Adhesive strength
Adhesive strength is the ability of sealants to bond to a particular substrate, including
adhesion during substrate movement. Since materials differ substantially in their adhesive
strength to a particular substrate, manufacturers should be consulted for adhesion test sam-
ples on proposed substrates.
Adhesive failures occur when the sealant loses its bond with the substrate (Fig. 5.28).
Adhesion failures typically occur due the inadequate, improper, or complete lack of
primers, not preparing the substrate properly (such as removing curing or form-release
agents), or incompatibility between the sealant and substrate.
Cohesive strength
Cohesive strength is the ability of a material’s molecular structure to stay together inter-
nally during movement. Cohesive strength has a direct bearing on elongation ability.
FIGURE 5.28 Adhesive failure of sealant; note disbonding from edges of
joint. (Courtesy of Coastal Construction Products)
