Durability of buried and encased ground anchorages and structural components; requirements for corrosivity assessment and protection to ensure service life

Corrosion of steel components in ground is often given insufficient detailed attention during the initial design and subsequent service period of anchorages whether rock bolts or tie bars using reinforcement steel or multi-unit tendons using high yield steel. The corrosion process is dependent on many factors such as ground type, and ground and ground water factors including resistivity, chemistry and microbiology. Numerous procedures relating to the assessment of soil aggressiveness/corrosivity are available but most are aimed at general metal loss and not localised corrosion in terms of rate of attack or consequence, where pitting of pre-stressed components can be a precursor to environmentally assisted cracking and ultimately failure. The paper identifies the requirements for assessment of corrosivity and discusses the provision of durability for anchorage components in aggressive environments.

• Introduction

• Assessment of aggressiveness/corrosivity

• Corrosion of steel tendon within grouted length

• Principal methods of protection against corrosion

• Conclusions

• References