Assessment of the Deteriorations in Sea-Side Concrete Bridges in the Cold Region by In-Situ Tests on the Surface Layer of Concrete

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Title: Assessment of the Deteriorations in Sea-Side Concrete Bridges in the Cold Region by In-Situ Tests on the Surface Layer of Concrete

Author(s): Masami Shoya, Yoichi Tsukinaga, and Shuichi Sugita

Publication: Special Publication

Volume: 128

Issue:

Appears on pages(s): 69-84

Keywords: alkali-aggregate reactions; bridges (structures); chlorides; corrosion; cracking (fracturing); deterioration; harbor structures; nondestructive tests; scaling; Materials Research

Date: 11/1/1991

Abstract:
It has been reported recently that there exists early-stage deterioration in many concrete structures due to salt injury, alkali-silica reaction, freezing-thawing action, and their combined actions. Thus, it will be important to assess the change in quality of the surface layer of concrete because the deterioration often appears on the surface of the concrete by way of cracking or scaling. In this paper, the authors describe the results of field investigations on the state and the cases of deterioration in three seaside concrete bridges located in Aomori prefecture, in the most northern districts of the mainland. Various tests were performed on surface layers of concrete incorporating conventional nondestructive methods. A large amount of chloride ion, in excess of 1 kg/m3 in soluble chloride, had accumulated at the depth of cover, and severe corrosion of reinforcing bars was observed in all bridges. In the case of a reinforced concrete bridge that had been in service for more than 50 years, not only the depth of carbonation and penetration of chloride, but also sulfate intrusion, were deeper than the cover depth. The severe damage caused by alkali-silica reaction was also observed in the pier of a prestressed concrete bridge and newel post of a reinforced concrete bridge. It was possible that the penetration of chloride greatly affected the degree of deterioration due to alkali-silica reaction. The change in quality of the surface layers of concrete brought about by deterioration was assessed successfully by in situ tests based on the pulloff tensile strength, rapid air permeability, and depth of carbonation.