Location
University of Jinan, Jinan, China
Keywords
marine environment, penetrants, chloride ion concentration, penetration, durability
Abstract
The intrusion of chloride ions in concrete served in the marine environment is the leading cause of corrosion of steel bars. This paper examined the result of a long-term survey on the actual structure (the Tomakomai breakwater) treated with a set of penetrants partly. The survey was conducted twice, in the 12th and 20th years after construction.
The results showed that the penetrants could effectively reduce the penetration of chloride ions into concrete. After using the penetrants, the calculated surface chloride ion concentration was decreased by 5.04%/72.18% (the 12th year/the 20th year). As the service years increase, surface chloride ion concentrations between treated and untreated concrete parts vary significantly. It was observed that the effect of the penetrants continued even after 20-years served in the actual severe environment. In the 12th year, the theoretical surface chloride ion concentration of all the concrete has exceeded 13 kg/m3, which is the value for durability design. Therefore, in the process of durability design for the marine structures, it is proposed to take a higher surface chloride ion concentration as a design value or take some powerful measures to improve concrete durability.
After 12 years of use, the chloride ion diffusion coefficient tends to stabilize for untreated concrete. It is about 0.1cm2/year. While, for the treated, at the 12th year, the chloride ion diffusion rate was about half that of the untreated group. However, as the protective effect of the penetrant layer gradually weakened, at the 20th year, the chloride ion diffusion rate was about twice that of the untreated group, and the turning point was about 15.11 years. It means that If the impregnating agent is used for maintaining the concrete surface when construction, it is necessary to maintain it again in nearly 15 years.
Evaluation of the chloride ions penetration into concrete structure with the surface penetrants served in cold marine environment for 20 years
University of Jinan, Jinan, China
The intrusion of chloride ions in concrete served in the marine environment is the leading cause of corrosion of steel bars. This paper examined the result of a long-term survey on the actual structure (the Tomakomai breakwater) treated with a set of penetrants partly. The survey was conducted twice, in the 12th and 20th years after construction.
The results showed that the penetrants could effectively reduce the penetration of chloride ions into concrete. After using the penetrants, the calculated surface chloride ion concentration was decreased by 5.04%/72.18% (the 12th year/the 20th year). As the service years increase, surface chloride ion concentrations between treated and untreated concrete parts vary significantly. It was observed that the effect of the penetrants continued even after 20-years served in the actual severe environment. In the 12th year, the theoretical surface chloride ion concentration of all the concrete has exceeded 13 kg/m3, which is the value for durability design. Therefore, in the process of durability design for the marine structures, it is proposed to take a higher surface chloride ion concentration as a design value or take some powerful measures to improve concrete durability.
After 12 years of use, the chloride ion diffusion coefficient tends to stabilize for untreated concrete. It is about 0.1cm2/year. While, for the treated, at the 12th year, the chloride ion diffusion rate was about half that of the untreated group. However, as the protective effect of the penetrant layer gradually weakened, at the 20th year, the chloride ion diffusion rate was about twice that of the untreated group, and the turning point was about 15.11 years. It means that If the impregnating agent is used for maintaining the concrete surface when construction, it is necessary to maintain it again in nearly 15 years.
