RESEARCH ON APPLICABILITY OF NEW MATERIALS TO MARINE STRUCTURES IN TROPICAL CLIMATES -SPECIMENS EXPOSED FOR 1 YEAR -

摘要

This study aims to investigate the applicability of newly developed structural materials, which are lightweight and highly durable, to marine structures from the aspect of reducing their life-cycle cost Since corrosion is primarily the determining factor of the service life of marine structures, exposure tests have been conducted in this study with the focus on corrosion resistance of new structural materials. Twenty-one new materials have been exposed to the environment at three sites: the tropical island Okinotori-shima and subtropical island Miyako-jima, both in Japan, and a hygro-thermostatic room in a laboratory. These experiments started in 1999 as five-year exposure tests. The authors have reported on the selection of potential new structural materials for marine structures (six nonferrous metals, eight steels, four composite materials, and three rope materials), outline of exposure tests, and results of initial performance tests on these materials. As of October 2001, specimens at an age of 2 years were retrieved and are now being examined. This paper reports on the findings obtained after the publication of the previous paper, including the observation and test results of specimens retrieved in 2000 at an age of 1 year. After publishing the previous paper on the ongoing tests, tension tests on unjointed and jointed specimens and SEM observation of corrosion specimens were conducted. Some of the steels exhibited severe corrosion, as well as significant strength losses. Specimens other than those began to exhibit tendencies towards strength changes depending on the material type and specimen type (unjointed/jointed), though not very evident. SEM observation of corroded specimens revealed differences in the state of corrosion among materials.