Selecting concrete pavement joint sealants. II: Case study

A comprehensive test protocol, described in Part I of this paper, has been used to evaluate the adhesive strength, viscoelastic properties, and shear fatigue behavior of two polyurethane joint sealants for use in undoweled co ncrete highway joints. The results of these tests showed that the protocol was able to assist in selecting the more suitable sealant for the expected service conditions in New Brunswick, Canada. Sealant A, a coal-tar modified polyurethane with a glass transition temperature of -20.7 degrees C, showe d a significantly reduced flexibility at a severe low temperature of -40 de grees C. This low temperature induced loss in flexibility was supported by the relatively low peel force required to initiate cohesive failure and the relatively high resistance to shear deflection noted with the shear fatigu e test. Sealant B, on the other hand, was found to have a glass transition temperature of -43.2C and maintained its flexibility at extreme low tempera tures for all dynamic tests performed. Using dynamic mechanical analysis, n either sealant showed significant degradation at high temperatures or when subjected to water or ethylene glycol exposure.