This is the third lecture in the Thomas Telford Prestige Paper series, showcasing award winning papers. This paper upon which this lecture is based, won the Telford Premium Prize at the 2022 ICE Awards Ceremony.
This lecture explores the forensic lessons from durability failures of older, “legacy” reinforced concrete assets and examines how performance can be enhanced in hostile environments, and assured by effective corrosion monitoring and management strategies.
Legacy reinforced concrete assets often fail to achieve their design service life, traditionally taken as 60 years for buildings and 120 years for bridges. Forensic examination identifies premature reinforcement corrosion as a common cause of deterioration. The reason is seated in a historical lack of appreciation about exposure conditions and how best to design for durability, combined with sub-optimal construction practices and lack of whole life maintenance. The result is unexpected damage that requires intervention to extend the shortened asset life.
Surely we can now just sit back and rely on the durability provisions in EN 206 & BS 8500-1 to create durable assets a simple answer is maybe not, because we expect a longer asset life that may be outside the scope of BS 8500-1. Durability performance criteria in BS 8500-1 are still being tightened, as we learn more above the aggressiveness of chloride salt, which presents our greatest challenge to asset performance. Outside of the UK, infrastructure is being built in environments that are “hostile” to reinforced concrete, where EN 206 & BS 8500-1 are unlikely to be appropriate.
For these environments, performance-related durability methods have been developed, using predictive chloride ingress models for the required service life. Even then, the risk remains that the design intent may not be realised due to poor build quality, requiring regular inspection and monitoring to assure asset performance.
