ABSTRACT
From the analysis, we decided that the cracking beneath the duct slab had occurred due to nonstructural reasons such as fixed boundary conditions and shrinkage, and temperature during curing at the construction stage. With regard to traffic combustion, defects caused by carbonation such as corrosion, spalling, and deterioration can be rapidly developed. In particular, the carbonation within crack zones can even more drastically damage the reinforced concrete. The goal of repair for the fine cracks focused on sustaining the durability. Cracks larger than 0.3 mm in width were injected by epoxy pressured with rubber band, and then the hair crack zone (approximately 6 m wide beneath the duct slab) was rendered three times with cement paste by painter roller. In addition, approximately 28 cracks were checked for the warranty of injection by hand coring. More care was needed for the repair of the portal area due to deterioration by atmosphere and concentration of combustion products (exhaust fumes etc).
