The Architectural Institute of Japan (AIJ) published Recommendations for Durability Design and Construction Practice of Reinforced Concrete (draft) in March 2004. These recommendations were proposed as model guidelines for performance-oriented design in the materials/construction field, for the first time specifically dealing with performance design in the materials/construction segment of AIJ. In particular, a theoretical system was formulated by analyzing and organizing the durability performance of reinforced concrete buildings, based on which a framework of durability design was proposed. This framework consists of three routes : “performance-based design : general approach, ” “standard-specification-based design, ” and “performance-based design : special approach.” These recommendations are also significant in that they unified the methods of determining the limit states of structures and members in terms of performance and defined them in relation to the limit states of materials, such as reinforcement, concrete, and finishing materials.

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Test methods for diffusion coefficient of chloride ions in concrete were published from Japan Society of Civil Engineers in 2004. One method is named 'Test method for effective diffusion coefficient of chloride ions in concrete by migration', and the other one is called 'Test method for apparent diffusion coefficient of chloride ions in concrete by immersion in salt water'. Not only the details of test methods but also mechanisms of chloride ions movement in concrete are explained in this commentary, so theoretical backgrounds of these test methods are easy to be understood. An outline of EPMA method, which is used to determine chloride ions content, are given with an example of measurement. It is refered to how to utilize chloride ions coefficient measured from these methods in a concrete performance verification system.

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When constructing a concrete structure, it is important to select a concrete with placing performance suitable for the relevant construction conditions and structural conditions. This paper summarizes the current practice and problems of concreting and discusses technical systems for evaluating the placing performance of fresh concrete states, which should be introduced to ensure the construction of concrete structures with high durability and reliability while preventing initial defects.

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The rebound number were measured by rebound hammer for the specimen made under various conditions, and concrete strength estimation was proposed by examining the relationship between the rebound number and compressive strength of them. The effect of the carbonation and the correlation between the rebound number and the static modulus of elasticity, the ultrasonic pulse velocity and the surface moisture of concrete were examined too. In addition, the rebound number was measured by rebound hammer for large scale or real scale concrete specimens, and the application of concrete strength estimation was evaluated. As the results of the examinations, it was confirmed that the carbonation had an very large effect on the rebound number. It was also shown that concrete strength estimation could be applied enough for the concrete at ages less than about 56 days.

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This paper presents a summary of the system and the user interface of the inspection software developed for maintenance of the concrete bridges. This system was developed with the concept that inexperienced engineers can easily diagnose and point out the necessity for the detailed inspections from a visual check. The software should also enable user to refer to many samples of deterioration patterns and to the structure types when clear diagnosis cannot be made. The causes and levels of deterioration are determined by the software, based on the data collected during the visual inspection. In this process, the inspection methods related to the causes already listed in the database are deduced automatically. Finally, the current condition and the result of diagnosis are stored part-by-part for each inspected structure so the history of inspection can also be traced.

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