ABSTRACT
ABSTRACT. The Naminoue bridge is a prestressed concrete type bridge. It is a bayside bridge constructed in 1983 in Okinawa prefecture, Japan. Okinawa is southernmost island in Japan, and is in the sub-tropical zone. Because of this, the environmental conditions affecting the bridge are very severe, especially salt which attacks the prestressed concrete members. In order to prevent deterioration of the members from salt attacks, prestressed members have to be coated with a special coating material within a few years. But, in Japan, neither a simplified classification standard for environments for concrete structures nor suitable standards for selecting coating materials have been established. A series of tests whose object is to evaluate the effects of several coating systems on the prevention of salt attack is carried out. Tests are all carried out using concrete specimens-first, an exposure test under the real environment; second, an exposure test in a simulated splash zone; last, an accelerating laboratory test under drying and saturating cycles. In this paper, test results are presented and suitable materials for the prevention of the salt attack are discussed. Also, a simplified evaluation diagram for coating systems is suggested.
