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Title: Chloride Corrosion of Reinforcing Steel in Silica Fume Concrete Exposed to Marine Environment

Author(s): N. Takage

Publication: Symposium Paper

Volume: 126

Issue:

Appears on pages(s): 479-498

Keywords: chlorides; corrosion; electrical resistance; half-cell potential; marine atmospheres; penetration tests; reinforcing steel; silica fume; Materials Research

DOI: 10.14359/2276

Date: 8/1/1991

Abstract:
Exposure tests of silica fume concrete with embedded steel bars were carried out in marine environments such as the Inland Sea of Japan, the Pacific Ocean, and the Sea of Japan, in the Kansai district. The effects of water-to-cementitious material ratio, silica fume content, chloride ion content in mixing water, and concrete cover on the chloride corrosion of reinforcing steel were studied by measuring half-cell potential, electric resistance, pH value, depth of carbonation, pore volume, and chloride ion content. When tap water was used as the mixing water and concrete cover was 10 mm, the longitudinal crack due to chloride corrosion was observed in silica fume concrete specimens in about 3 years. Chloride ion penetration into silica fume concrete was much lower in comparison with concrete without silica fume, however, chloride at the region 2 cm from the concrete surface was high enough for embedded steel to corrode. When concrete cover was 25 mm, no longitudinal crack was observed in silica fume concrete specimens until about 3 years. It is necessary to keep sufficient concrete cover, even in silica fume concrete. Chloride corrosion in concrete was accelerated by using silica fume when saline solution was used as the mixing water.