Ten Year Exposure Test of Precracked Reinforced Concrete in a Marine Environment

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Title: Ten Year Exposure Test of Precracked Reinforced Concrete in a Marine Environment

Author(s): K. Sakai and S. Sasaki

Publication: Special Publication

Volume: 145

Issue:

Appears on pages(s): 353-370

Keywords: Carbonation; chloride ions; corrosion; corrosion resistance; crackinq ffrocturinq); deformed reinforcement; epoxy resins; exposure; marine atmospheres; rebars; reinforced concrete; tests

Date: 5/1/1994

Abstract:
This paper describes the results of a ten-year marine exposure test of reinforced concrete. Sixteen pre-cracked test specimens were examined. The target crack width was 0.2mm. The dimensions of the specimens were 15x15x100cm. Ordinary deformed bars and epoxy-coated deformed bars, as well as normal portland cement and portland blast-furnace slag cement were used. The water-cement ratio in the mixture proportions ranged from 0.320I to 0.483%. The effect of nitrite-based corrosion inhibitor was also examined. From the exposure test results, the following conclusions were drawn: When the water-cement ratio was low, the penetration of chloride ions into the concrete was low; the chloride-ion content on the surface of blast-furnace slag cement concrete was greater than on the surface of concrete made with ordinary cement, but was smaller inside; there was a tendency for the chloride-ion content around the reinforcing bars in concrete portions with small cracks to be greater than in portions with large cracks; ten years of exposure caused an increase in crack width due to the corrosion of the reinforcing bars; although the effectiveness of epoxy-coated reinforcing bars in preventing corrosion was obvious, severe corrosion was found in one coated bar. The epoxy-coated bars used were produced for the first time in Japan, and test results indicate that there were problems with the early production technology; there was no beneficial effect from corrosion inhibitor after ten years.