Development of the self-compacted and high-strength concrete for cold region

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This purpose of this study is to develop the self-compacting and high-strength concrete for the cold region to reduce an environmental load. Most important results are summarized as follwos :(1) We developed the superplasticizer for the self-compacting and high-strength concrete in cold region. The effect of the chemical structure of superplasticizer on the fluidity, fluidity retention, retardation of hydration, and high durability of concrete was examined when the temperature was varied. As a result, it was confirmed that the heterologous graft copolymer having a long and short graft chains shows highly cement dispersed and low retardation of cement hydration, and the graft copolymer containing longer graft chains satisfied both high fluidity and high durability of concrete at low temperature.(2) It was indicated that the reduction of autogenous shrinkage of concrete is very important to prevent cracking the self-compacting and high-strength concrete for the cold region. Moreover, it was imposed that both to control the ionic concentration of liquid phase in concrete and to containing a large amount of fly ash were able to decrease the autogenous shrinkage.(3) The prediction method of the mix proportion for the self-compacted and high-strength concrete was proposed in order to make concrete mix design easily when the quality of powder and aggregate were varied. The critical state of self-compactability could be asumed that the bridge structure of the coarse aggregate covered with adherent mortar firms and was influenced strongly by the concentration of coarse aggregate and the fluidity of mortar. Based on this assumption, the maximum values of both coarse aggregate and fine aggregate and the unit water content (water-powder ratio) when concrete was satisfied of the self-compactability could be calculated by using the probability model based on the Monte Carlo method and the fractal theory respectively.