Effects of Shape and Bond Strength on Adhesive Failure of Joint Sealants

Abstract

Currently, joint sealant is designed without consideration of the bond strength between the concrete and the sealant and the effect of shape on stress concentration. This often leads to adhesive failures within 1.5 years, earlier than the expected service life of the joint sealant, which is 20 years. In adhesive failure, the strength of the bond and the stress of the interface between the sealant and the face of the joint reservoir play a very important role. To examine the nature of the bond along the sealant/joint well interface, experimental bond tests were conducted. In addition, the stress distribution on the interface was also investigated according to geometry (Shape Factor [SF] and degree of curvature [DoC]). Re-evaluation of the SF was conducted, and a new design factor, DoC, was introduced and investigated through the finite element method of analysis. With these factors, the reduction of bond strength and increase in the stress at the interface can be limited reducing the potential for early adhesive failure. Based on this study, the effect of joint preparation (dirt and moisture) on joint strength and shape (SF and DoC) of joint sealant should be considered when designing and installing sealants.