Instrumentation for reinforced concrete durability monitoring of Qingdao Bay Bridge

The Qingdao Bay Bridge with a total length of 28,047 m is currently under construction in Qingdao, Shandong Province, China. As part of a sophisticated structural health monitoring and safety evaluation system being implemented on the bridge, a durability monitoring system is specifically designed to monitor corrosion-related parameters in recognition of severe coastal environmental conditions around the bridge such as about 50 times freezing-thawing cycles per year and 29.4% to 32.9% saline concentration. The Anode Ladder System, the Expansion Ring System, and the Embedded Corrosion Instrument (Type ECI- 1) have been embedded into the bridge for durability monitoring. Two categories of corrosion-related parameters are measured. The first category is about the causes to induce and affect corrosion, such as temperature, relative humidity, and concrete resistivity. The second category is electrode assemblies characterizing the corrosion extent of steel bars, such as limit values for de-passivation, potential difference, and polarization resistance. The monitoring data will benefit the bridge owners and engineers to optimize protective measures and príoritize maintenance activities targeting to prolong service life of the bridge.