Selecting concrete pavement joint sealants. I: Proposed test protocol

Sealants used to seal the transverse contraction joints used in joining con crete highway sections without dowels must be flexible enough to withstand excessive conditions such as large temperature fluctuations, severe pavemen t deflection due to heavy truck traffic, and prolonged moisture exposure. C hoosing the most appropriate sealant for the expected service condition fro m the wide variety of sealants available on the market today can be a daunt ing task. In Part I of this paper, a comprehensive test protocol that corre lates sealant viscoelastic properties with the sealant resistance to deflec tion is presented. It is proposed that the selection of a sealant should be based on a complete evaluation consisting of three test procedures: (1) th e ASTM C794 adhesion-in-peel test to assess concrete/sealant adhesion; (2) dynamic mechanical analysis (DMA) to evaluate sealant flexibility by determ ining the glass transition temperature, T-g; and (3) the shear fatigue test developed by the writers to analyze sealant performance when subjected to severe pavement deflection in combination with various environmental condit ions. Part II of this paper will present the results of testing and compari son of two polyurethane joint sealants using this proposed test protocol.