Impact of Steel Properties on the Corrosion of Expandable Rock Bolts

Abstract

The selection of ground support for underground excavations typically focuses on matching a system to the anticipated ground conditions. In this context, the emphasis on materials selection involves picking a rock bolt type that meets a set of predefined capacity and deformation properties to manage the applied loads. Exposure of ground support to corrosive environments in underground hard rock mines can result in significant material degradation and loss of mechanical performance. This can have significant repercussions on the structural integrity of excavations in rock and potential falls of ground that may endanger the safety of workers and equipment. Consequently, there is a need to ensure that the selected rock bolt provides sufficient resistance to corrosion for the working life of the excavation. Current design practice is limited in selecting rock bolt types perceived as more resistant to corrosion, e.g., grouted versus friction rock stabilizer bolts. This investigation suggests, however, that there are significant variations in corrosion susceptibility of rock bolts that may otherwise display similar mechanical behavior. This has significant implications for mines operating in very corrosive environments.