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Chloride penetration and bar corrosion of concrete in splash zone
The deterioration of reinforced concrete structures in marine environment is more severe than deterioration of structures exposed to most other environments. Reinforced concrete in the splash zone is the most seriously damaged part of a structure. The environmental characteristics of concrete in the splash zone are long dry periods followed by periods when direct contact with seawater takes place. There is cyclic drying and rewetting. In order to study the penetration of chlorides and the chloride induced corrosion an experimental study has been carried out. Specimens of reinforced concrete are made with a water to binder ratio (W/B) ranging from 0.41 to 0.65. Portland cement has been replaced by fly ash with a fly ash content ranging from 0 % to 70 %. The thickness of the cover was chosen to be 30 mm. The specimens are kept in a standard curing room for 28 days, then oven dried at 40 deg C for 10.5 h, dipped in an aqueous chloride solution with a concentration of 6 % for 1.5 h. This procedure has been cyclically repeated every 12 hours for 252 cycles. Experimental results show that both the chloride penetration depths and the chloride content increase, and bar corrosion becomes more serious with decreasing W/B and increasing the fly ash content. The influence of W/B on chloride penetration is in contradiction with results from other authors. This may be explained by the workability of fresh concrete. In practice concrete with low W/B is difficult to compact correctly. It is recommended to use superplasticisers at low W/B. If part of the Portland cement is replaced by fly ash young concrete especially has a lower density of hydration products und is therefore more susceptible for chloride penetration.
Chloride penetration and bar corrosion of concrete in splash zone
The deterioration of reinforced concrete structures in marine environment is more severe than deterioration of structures exposed to most other environments. Reinforced concrete in the splash zone is the most seriously damaged part of a structure. The environmental characteristics of concrete in the splash zone are long dry periods followed by periods when direct contact with seawater takes place. There is cyclic drying and rewetting. In order to study the penetration of chlorides and the chloride induced corrosion an experimental study has been carried out. Specimens of reinforced concrete are made with a water to binder ratio (W/B) ranging from 0.41 to 0.65. Portland cement has been replaced by fly ash with a fly ash content ranging from 0 % to 70 %. The thickness of the cover was chosen to be 30 mm. The specimens are kept in a standard curing room for 28 days, then oven dried at 40 deg C for 10.5 h, dipped in an aqueous chloride solution with a concentration of 6 % for 1.5 h. This procedure has been cyclically repeated every 12 hours for 252 cycles. Experimental results show that both the chloride penetration depths and the chloride content increase, and bar corrosion becomes more serious with decreasing W/B and increasing the fly ash content. The influence of W/B on chloride penetration is in contradiction with results from other authors. This may be explained by the workability of fresh concrete. In practice concrete with low W/B is difficult to compact correctly. It is recommended to use superplasticisers at low W/B. If part of the Portland cement is replaced by fly ash young concrete especially has a lower density of hydration products und is therefore more susceptible for chloride penetration.
Chloride penetration and bar corrosion of concrete in splash zone
Zhao, Tie-jun (author) / Gao, Qian (author) / Wang, Xiao-gang (author)
2003
9 Seiten, 8 Bilder, 2 Tabellen, 9 Quellen
Conference paper
English
Chloride Penetration and Bar Corrosion of Concrete in Splash Zone
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