Sun, heat and age harden the surface of sealants and asphaltic coatings faster than the material below, so the skin shrinks and crazes into a network of cracks. Shallow alligatoring on sealant can be cosmetic, but deep cracking means loss of elasticity and is a sign the joint is nearing the end of its service life. Field crews probe the cracks to judge depth.
Sealant on the coping is alligatoring pretty deep, add those joints to the R&R list.
Also heard as
- alligator cracking
Related terms
Reversion
Cured sealant breaking down and turning soft, sticky or gooey again with heat, sun or chemical attack.
R&R
Remove and replace: cutting out old sealant completely and installing new sealant in the cleaned joint.
Cohesive failure
A sealant tearing apart within itself while staying stuck to both joint faces.
Polyurethane sealant
A tough, paintable elastomeric sealant used widely on concrete, masonry and traffic joints.