Study of Influence of Construction Defects on Durability of Reinforced Concrete

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1. The properties of concrete influenced by material segregation were successfully evaluated using "minute compressive test, minute tensile test and minute diffusion cell test.2. It was confirmed that the rates of macrocell and microcell corrosion were largely influenced by material segregation. In particular, the material segregation made the rate of steel corrosion faster due to the different property of concrete between upper part and lower part of concrete or gap between steel bar and cement matrix.3. The rate of steel corrosion of horizontal steel bar in dry-wet condition was faster than that in submerged condition.4. It was confirmed that the steel corrosion in horizontal steel bar could be controlled using steel bar with cement past cover or fly ash.5. It was confirmed that the rate of carbonation, oxygen permeability and steel corrosion in concrete increases with temperature rising. It was also confirmed that the above phenomena followed Arrhenius theory. The activation energies of carbonation, oxygen permeability and steel corrosion in concrete could be obtained by Arrhenius theory.6. The influence of joint treatment on steel corrosion under tidal zone was large in early stage of concrete (3 months), otherwise the influence decreased in long term exposure. On the other hand the influence of joint treatment on steel corrosion on land was large for long time. And the most effective treatment method for reducing the corrosion rate at joint was removal of laitance on the old concrete.7. It was confirmed that the corrosion rate of steel exposed to concrete- atomistic condition became large when the surface of concrete covered by sand.8. The influence of heterogeneity of concrete on anticorrosive curren^+ could be evaluated.