Corrosion in Concrete Bridge Girders

A critical examination concerning the problem of corrosion in concrete bridge girders with recommendations to resolve the issue. This paper provides a strong engineering and safety background into the problems associated with corrosion and bridges. The procedure used in this paper is presented through the careful examination of the existing literature. Some of the literature may be a few years old but the past is prologue; what went before is as relevant as what is going on today. Other literature presented is quite contemporary, and all of the materials presented in this paper are relevant. Especially relevant are studies that have been conducted six, seven, eight and more years ago; compared and contrasted with what engineers and scientists are saying in the latest bulletins and research documents. For example, the American Association of State Highway and Transportation Officials (AASHTO) offered standard specifications for highway bridges in the 1990s that seem to be practical and yet have clearly not provided a workable solution to the ongoing problems of corrosion. In the article titled “Reliability of Reinforced Concrete Girders Under Corrosion Attack,” the authors (Frangopol, et al, 1997) embrace the AASHTO strategy; first, the effects of corrosion “on both moment and shear reliabilities” are carefully investigated; second, a “reliability-based design approach” that is based on minimization of “total material cost including corrosion effects” is taken into consideration. This article suggests that taking into consideration the environmental stressors on concrete (due to corrosion), along with the AASHTO standards, can then be plugged into “reliability-based optimization software.” That software is a product of the combining of general–purpose optimization software and a Monte Carlo simulation–based evaluation program.Hence, the procedure for coming up with reliable estimates of the life expectancy of concrete girders comes in two phases, according to this research. Phase one spans the time from construction to corrosion initiation; phase two, from corrosion initiation to time when “unacceptable levels of section loss have occurred.” But is this procedure proactive or reactive? The answer - it is indeed reactive, and it is also outdated. But nevertheless it should be researched and understood because it is part of the literature. Science cannot predict future conditions and dynamics based on models and hypotheses alone. A foundation for the projections of the future is based on evidence from the past.