Two 3000-ton capacity reinforced concrete coal silos and one 5000-ton capacity reinforced concrete
coal silo in the Hunter Valley, New South Wales, Australia were deteriorated due to corrosion of steel
reinforcement. The storage silos are a critical asset necessary to facilitate the efficient delivery of coal.
Serious concrete deterioration of the silos and corrosion to external post-tensioned cables had the
potential to catastrophically interrupt the supply chain. A risk and structural assessment of the silos
was undertaken and a condition investigation completed.
A remedial option scenario analysis was conducted for each silo to provide a serviceable strengthening
solution.
The remedial solutions ultimately adopted used either carbon fiber laminates (CFL) and/or post
tensioned cables, all externally applied. In both cases where delaminated (drummy) zones of concrete
were present or where concrete had severely spalled (internally and externally) concrete repair was
undertaken with a sprayed repair mortar. An elastomeric anti-carbonation coating system was then
applied to external silo concrete surfaces.
Keywords: reinforced concrete, silos, risk assessment, condition survey, concrete repair, structural
strengthening, and carbon fiber laminates.