Samenvatting

Monitoring material degradation can serve as an ‘early warning system’ to detect potential durability issues and optimize repair for tunnel structures. The COB network has conducted an inventory study on sensors and other instruments that can be used to measure the necessary chemical and physical parameters.

Degradation of materials used in structural elements of a tunnel construction can cause damage and eventually lead to tunnel closure. To support tunnel owners and their consultants in identifying, preventing, and/or mitigating these failure mechanisms, the COB network researches material degradation. In 2022 a report has been published that describes the most important degradation mechanisms and briefly addresses monitoring techniques. Now, the possibilities for monitoring material degradation are explored in much greater depth.
The inventory consists of four parts: 1) environment and structure, 2) concrete, 3) metals, and 4) protective coatings. For each sensor, a factsheet is given with the primary characteristics, including sensor types, measurement principles, and testing set-up. Also, their applicability, availability, and costs are discussed.