MAINTENANCE OF RC HOLLOW SLAB BRIDGE DAMAGED BY FREEZING PREVENTING AGENT AND CONTAMINATED SALT 

Investigations of comprehensive maintenance targeting 100-year-design life about a RC hollow slab bridge, which was damaged by salt contamination with use of initial chloride from sea sand and deicing salt, were conducted. The bridge was deteriorated seriously by reinforcement bars corrosion, cracks on concrete surface and exfoliations, and needed immediate repairing. It was clarifies that removing of concrete 30mm deeper than rebar position and repair of cross section 55mm over thickness were necessary to the bridge by present conditions and prediction using neural network method.

　

REPAIR OF RC HOLLOW SLAB BRIDGE DAMAGED BY CHLORIDE ATTACK USING SPRAYED MORTAR

This paper describes the repair of the bottom side of a RC hollow slab bridge damaged by deicing salt and contaminated chloride. It was clarified that removing of concrete 30mm deeper than rebar position and repair of cross section 55mm over thickness were necessary to the bridge by present conditions and prediction. In this experiments using actual bridge models, it was found to be able to remove concrete by water-het chipping technology and compact repair mortar by spraying technology under such hard condition. Since it was found that the quality of the mortar was influenced by the execution/environment condition, the importance of designing for repair, controlling the quality of mortar and inspecting initially to repaired bridge under consideration of such influence was noted