The Densified system containing homogeneously arranged ultra-fine particle (DSP) has been developed as a ultra-high strength concrete. This material consists of cement, ultra-fine particles such as silica fume and a large quantity of superplasticizers. It allows a large water reduction to obtain ultra-high strength and yet achieves a good fluidity of concrete for casting. In this report, the mechanical properties of DSP concrete and the hardened mechanism or morphology of DSP materials were explained. In addition, some application of DSP for building materials and industrial materials were introduced.

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Fukatani Bridge, under construction adopting cantilever erection method by advancing girder (P & Z system) for superstructures, is located in the severe environmental exposure conditions of seaside marine splash zone. The durability of concrete structures, therefore, depends on the quality control and good practice in the construction-site. This paper describes the practical process of concrete construction considering following subjects; the suitable selection of mix-proportion, chemical admixtures (superplasticizer) and placing method, the experimental test of chloride ion content and alkali content of concrete, the determination of allowable limit of chloride ion and alkali, strictly setting of concrete cover, complete compaction using a great number of vibrators and so on.

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