Development of New Embedded Expansion Joint Using High Flexibility Stone Mastic Asphalt

Abstract

Replacement of expansion joint of highway viaducts is one of the current technical challenges in order to improve driving comfort in highway network. Generally, embedded expansion joints have been used for reinforced bridges and pre-stressed concrete bridges. As for the embedded expansion joint, base course gussasphalt strengthened with expanded metal is used for absorbing thermal expansion of adjacent bridges. This base course is generally damaged by the flexural rotation at the girder end under low temperature condition; therefore, structural improvement especially enhancing flexibility of pavement is demanded for improving durability. In this study, new asphalt material called "High flexibility stone mastic asphalt" is used as a base course, because this high flexibility asphalt is considered to accommodate the thermal expansion as well as flexural rotation even under low temperature. This new joint is adopted the urban expressway viaduct in Japan. Fundamental experiments showed high durability performance of the new joint compared to those of the conventional joint and the field strain measurement also showed good performance under actual condition. This paper summarizes the structure and performance of the new embedded expansion joint in Japan.