Method To Evaluate Rigid-Pavement Joint Sealant Under Cyclic Shear and Constant Horizontal Deflections

Abstract

In recent years, the need for sealants in rigid pavement joints has become debatable, partly because of the unpredictable field performance of joint sealants. This inability to predict sealant performance stems from the fact that there is no laboratory evaluation method that accurately simulates field traffic and environmental loading conditions. A laboratory testing method was developed to predict the performance of rigid-pavement joint sealants. A research team at Virginia Tech designed a fixture that allows the evaluation of joint sealants under cyclic shear and static horizontal deflections. Shear deflection simulates vehicular loading, and horizontal deflection simulates expansion and contraction of concrete slabs due to temperature variation. Concrete specimens were prepared at a typical water-to-cement ratio of 0.45. Two aggregate types were used in the concrete mixes to evaluate the effect of aggregate type on sealant performance. Two commercially available sealants were investigated in the study. Sealant performance was evaluated for different joint widths and joint expansion. Specimens were loaded cyclically to failure; a 20 percent cohesive or adhesive debonding was considered a failure. A limited number of specimens were exposed to freezing and thawing cycles. The study showed quantitatively the effects of joint width, joint expansion, concrete aggregate type, and freezing and thawing cycles on sealant performance. Statistical models were developed to predict the number of loading cycles to failure for each sealant.