In Japan, during recent several decades, great number of civil structures has been constructed.However, many aged structures have deteriorated up to present days. In some cases, there are structures seriously damaged by ASR (Alkali Silica Reaction) or chloride attack, etc. As Japan is geographically surrounded by sea with a long coastline, many reinforced concrete structures are directly exposed to seawater and are seriously damaged by chloride attack. Therefore, a health-monitoring technique of these deteriorated structures is needed to prevent sudden collapse and also to save human life in unexpected accidents.
　The concept of smart structures is widely applied in car and airplane industries. Also, in civil engineering structures, a demand for the smart structure is gradually increasing. Originally, optical fiber was developed and widely used as a mass information carry medium. Recently, several research works have been carried out to apply optical fiber as a monitoring sensor for several types of materials,including steel, carbon fiber and concrete. One reason for these developments is that optical fiber has several advantages including non-conductivity, immunity to electromagnetic interference and low weight. In previous papers, high possibility for utilization of optical fiber as a monitoring sensor is suggested.
　In this study, many types of optical fiber sensors attached on the concrete surface were developed. Through many kinds of tests of specimens, detailed data on optical performance of optical fiber were collected. Overall performance of the optical fiber sensor as a concrete performance monitor is discussed.