Pack Rust Identification and Mitigation Strategies for Steel Bridges

Abstract

Pack rust or crevice corrosion is a type of localized corrosion. When a metal is in contact with a metal, or even non-metal, the metal starts to corrode, and rust starts to pack in between the surfaces. When significant development of pack rust occurs, it can cause overstressing of bolts and rivets causing them to fail, and it can bend connecting plates and member elements thus reducing their buckling capacity. Thus it is important to mitigate the formation and growth of pack rust in bridges. This study was conducted to determine if pack rust occurs frequently and thereby may pose a problem in the state of Indiana. The study is divided into three primary tasks. The first part of the study involves understanding the parameters involved in the initiation process of crevice corrosion and post-initiation crevice corrosion process. The second part of the study involves reviewing existing mitigation strategies and repair procedures used by state DOTs. The third part of the study involves identifying steel bridges with pack rust in Indiana. Analyses were performed on the data collected from Indiana bridges that have pack rust. This involved finding the components and members of bridges which are most affected by pack rust and finding parameters which influence the formation of pack rust. Pack rust in the steel bridges were identified using the INDOT inspection reports available through BIAS system. The study revealed that good maintenance practices helped in reducing pack rust formation. The study identified locations on steel bridges which have a high probability towards pack rust formation. A mitigating strategy possessing qualities which can show promising results is identified.

Pack Rust Mitigation Strategies for Flange Splice Connections in Steel Bridges

“…Previous studies demonstrated that effective alternatives to mitigate pack rust are required to address the high number of bridges with pack rust in Indiana. It was determined that splice connections required special attention (3,4). Therefore, the main purpose of this study is to test three mitigation approaches that can be implemented in the field to delay additional pack rust development.…”

“…It has been observed in the field that pack rust can range from simply staining at the mouth of the crevice to bulging of the overlapping plates to 0.75 in. or more (3,4). In steel bridges, this type of corrosion can be spotted in gusset plates, joints, splice connections, and other connections with bolted and riveted fasteners.…”

Main Advantages of Steel in Bridges Construction using improved corrosion

“…Corrosion costs in the infrastructure industry to $ 22.6 billion, of which $ 8.3 billion was spent on road bridges. [3] 1.1 COR-TEN STEEL DESCRIPTIONS These steels defined in the European standard are intended for use in welded, rivets or bolted structures, whose operating temperature is the environment and must have an improved resistance to atmospheric corrosion. [4] These are not intended to be heat treated, except for products that undergo a standardization forming (lamination process in which the final deformation is carried out within a temperature range such that the state of the material is equivalent to that of would be obtained after a normalization treatment and that allows the specified values of the mechanical characteristics to be maintained even after a new normalization treatment).…”

Development of a life-cycle cost analysis tool for improved maintenance and management of bridges

“…the buildup of corrosion within the crevice of two adjoining surfaces, as shown inFigure 2.13 Patel and Bowman 2018. …”

“…Oregon DOT uses a system of mechanical cleaning; the water saturated pack rust is first heated to a temperature range of 250°F to 400°F and then removed mechanically (by hammering the connection plate). In Missouri, a rust penetrating sealer made up of calcium sulfonate is used to mitigate the effects and occurrence of pack rust(Patel and Bowman 2018).…”