FIELD INVESTIGATION FOR REHABILITATION OF SEVERELY DETERIORATED CRCP ON BAN-ETSU EXPRESSWAY IN JAPAN

Abstract

 The 7 km section of CRCP was constructed on the Ban-etsu Expressway, which was opened in October 1990, in heavy snowy region of Northern Japan main island. The cracks had opened wide and the crack spacing had become narrow just after 9 year service, resulting in punch out on the surface. The deteriorated part of the CRCP section had been repaired with the partial depth patching using SFRC and asphalt overlaying. However, the similar severe deterioration has appeared on the other parts of the section recently. Therefore, in 2018, comprehensive investigations including material tests, excavation of the slabs and joints, FWD tests and electromagnetic radar survey were conducted to establish the rehabilitation strategy for the CRCP section. The investigations revealed that, since a large amount of salt solution is spread over the surface to prevent the frozen surface in winter, salt content was very high in cracked concrete slab and that most reinforcement bars were severely corroded there. The expansion of the corroded reinforcement causes and develops the horizontal cracks at the position of reinforcement bar. The thin upper layer of the cracked slab easily punch out due to traffic loads. This paper presents the results of the investigation and electromagnetic radar survey, then, discusses the mechanism of the horizontal cracking and possibility of prevention measures.