After the end of Second World War, many dams have been constructed for water resources, electricity, flood control and other purposes in Japan. Roller Compacted Dam (RCD) method was first applied in 1978 in the construction of Shimajigawa Dam and thereafter this method was successively adopted in the construction of approximately 40 dams. The layer concrete placing methods such as RCD method and Extended Layer Construction Method (ELCM) are now the typical methods in the construction of concrete dams. Considering the recent progress of concrete dam technology, Standard Specification for Design and Construction of Concrete Structures (Dam) was revised in 1996 by Japan Society of Civil Engineers. This paper provides a summary of the recent technical development and improvement in the field of concrete dam in Japan and some problems for a future study.

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Desalination and realkalization were developed as the electrochemical repair methods for concrete structures deteriorated by chloride corrosion of reinforcing steel or carbonation of concrete. Recently, these techniques are applied to actual structures. This paper describes not only state of the art of researches and trials on desalination and realkalization but also importance of the electrochemical repair methods in the future maintenance program system.

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Self Compacting Concrete (SCC) was developed in Japan about 12 years ago. Recently, a movement to develop and apply SCC is very active in other countries as well especially in Europe. RILEM established a technical committee on SCC in 1997 to prepare a state of the art report by 2000 and organized the first international symposium on SCC in 1998. In this trend, the Dutch concrete industry is a good example of that is realizing quick popularization of SCC most properly understanding the Japanese experience in the world.
In this article, the development and application of SCC in TheNetherlands are introduced focusing on the following points :
(1) The history of the development of SCC in the Netherlands
(2) Activities on SCC in the Dutch ready-mixed concrete industry
(3) Activities on SCC in the Dutch precast concrete industry
(4) Future view

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Experience in the last forty to fifty years shows that current design specifications, even if properly implemented, do not provide for adequate resistance of portland cement concrete to aggressive environments. Premature deterioration of concrete structures is still unacceptably high, and corrosion of reinforcement continues to represent the single largest cause of deterioration of reinforced concrete structures. This paper discusses on effective utilization of (1) mineral admixtures decreasing water permeability and chloride diffusivity of hardened concrete matrix, and (2) concrete surface coating materials preventing the ingress of deleterious agents into concrete. Including these two engineering countermeasures, overall design concept on durability enhancement of concrete structures under chloride contaminated harsh environments is discussed in this report.

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Many concrete structures in the Arab countries and Iran located near the Persian Gulf are suffering from early deterioration. This is caused by aggressive environment in the region, poor quality concrete made with contaminated materials and lack of good workmanship and curing. A comprehensive survey of the concrete structures in the south coasts of Iran has been conducted in the last 15 years. Results of visual inspections and tests show that the dominant deterioration problem is the corrosion of reinforcement in the concrete structures. Sulfate attack, salt weathering, alkali aggregate reaction and environmental cracking were also responsible for some damages to the concrete structures. This paper reviews the durability problem in the region. The main reasons for the early deterioration of the concrete structures are discussed. Necessary precaution actions, which have to be considered at the time of construction, are briefly described.

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