海洋環境下におけるステンレス鉄筋の適用性に関する検討

Abstract

For the application to port concrete structures under marine environment, corrosion-resistant property of three types of stainless steel bars (SUS430, SUS304 and SUS316) in concrete was studied by immersing each steel bars in the simulated pore solution in concrete and exposing concrete specimens, in which each steel bars was embedded, under marine environment. Results obtained are as follows. 1. In the sound concrete region without crack, no corrosion was observed in all stainless steels (SUS430, SUS304, SUS316) under high chloride ion content which was around 15 kg/m3 in concrete. Therefore, it can be judged that the chloride threshold level for corrosion of these stainless steels is more than 15 kg/m3. 2. In the cracked concrete region, no corrosion was observed in two types of stainless steel (SUS430 and SUS316). However, very small corrosion was observed in the only crack region on SUS304. This reason is considered to be larger crack width than SUS430 and SUS316. This indicates that some large crack width can not be allowed in case of the stainless steel which has similar corrosion-resistant property to SUS304. It is necessary to study on the maximum allowable crack width. 3. In case that stainless steel bar is applied to port concrete structures under marine environment, the life cycle cost can be lower than the case of carbon steel bar in some specific cases.