| With the rapid development of domestic construction, the amount of reinforced concrete has been increasing year by year, and the problem of durability has been increasingly prominent. One of the prime reasons the leading to concrete failures is reinforcement corrosion, and the chloride ion is the main reason leading reinforcement corrosion in concrete. In coastal areas, concrete surrounding in the high salt environment, there is a certain scale on preparation concrete with sea sand, leading reinforcement corrosion caused by chloride ions severely. Abroad to research and application shows that using mineral admixture and inhibitor is one of technological approaches solving the problem of reinforcement corrosion. Current research and application for mineral admixtures are more about fly ash , slag and silica fume, and less about metakaolin. Metakaolin is a aluminosilicate mineral admixture with strong volcanic activity. After mixing into concrete , it can play a better effect to improve the durability of concrete.Chloride ions in concrete can be divide into binding chloride ions and free chloride ions. There will be a reinforcement corrosion only free chloride ions concentration beyond the chloride threshold level. When the chloride concentration is about certain, the more about binding chloride, the less about free chloride, the probability less about reinforcement corrosion. Using metakaolin as mineral admixture, take research on the performance of chloride binding and effect factor. Take research on the influence of cooperation between adding metakaolin and inhibitor on corrosion of reinforcement. The following conclusions can be drawn:①Using metakaolin to replace cement partly in cement paste can significantly improve the performance of chloride ion binding. Between 0～40% metakaolin dosage , with the dosage of metakaolin increasing, the chloride binding rate enhance.②It's found that using metakaolin as a mineral admixture can significantly increase the content of Friedel's salt in cement paste, and the hydration product C-S-H gel contains a part of chloride ion by XRD analysis and SEM/EDS analysis. The performance of chloride binding of hydration products having are Friedel's salt and C-S-H gel.③Curing temperature and environmental factors have a great influence on chloride binding. High temperature curing descends the ability of chloride ion binding though the content of Friedel's salt decline. Sulfate has negative effects on chloride ion binding. Cations have a great influence on chloride binding rate, the performance of chloride binding is CaCl2﹥MgCl2﹥KCl﹥NaCl. The influence of pH value of soak solution on the binding rate is great.The higher the pH value is, the chloride ion binding rate is lower.④It can significantly improve the physical and mechanical properties of concrete and reduce the chloride ion penetration with metakaolin as admixture. In this paper, between 0～20% metakaolin dosage ,20% dosage of metakaolin can maximize the best effect to improve the mechanical properties and minimize chloride ion permeability of concrete.⑤Using metakaolin as admixture to preparation concrete based on sea water and seasand can improve the resistance of reinforcement corrosion. In this paper, between 10～20% metakaolin dosage , with the dosage increasing ,the rusty accumulation rate and weight loss of specimens decline and below the specimen without metakaolin.⑥The cooperation between adding metakaolin and organic or compound inhibitor on resistance of reinforcement corrosion in concrete based on seawater and sea sand are better. Adding 20% metakaolin and organic inhibitor, or adding 15% metakaolin and compound inhibitor have great resistance for reinforcement corrosion. The cooperation between adding metakaolin and inorganic inhibitor on resistance of reinforcement corrosion in concrete based on seawater and sea sand is worse. There is a accelerated effect on reinforcement corrosion when the dosage of inorganic inhibitor increase.
|
PDF Full Text Request