Real-time corrosion monitoring of an ultra-high performance fibre-reinforced concrete offshore raft by using an autonomous sensor system

Abstract

The excellent high-durability features of ultra-high performance fibre-reinforced concrete (UHPFRC) have been verified in laboratory studies, but its performance under service conditions are being studied. Indeed, structural health monitoring (SHM) can be considered an efficient strategy to assess built structures in which concrete matrix performance differs from that those found when assessing laboratory samples (variable actions, cracking, etc.). This work presents INESSCOM, an automated corrosion rate monitoring system, as an innovative support to SHM strategy to monitor UHPFRC structures in terms of durability. Its innovation lies in its durable and multi-parametric sensor designed to be embedded in multiple parts of a structure. The results from previous laboratory tests and those obtained during real-time monitoring of an offshore UHPFRC raft are presented. Acceptable deviation of 20% was obtained in corrosion rate measurements with the advantageous reference-electrode-free cell of the sensor with respect to the classical three-electrode cell. Furthermore, sensor provided accurate corrosion measurements in UHPFRC despite its extremely high electrical resistivity and large amount of steel fibres. After 17-month monitoring of the UHPFRC raft, excellent performance was evidenced under service conditions with corrosion rate values always <0.1 μA/cm2. Conversely, corrosion rate reached 0.4 μA/cm2 in a conventional concrete specimen installed for comparison. Corrosion initiation and propagation stages were clearly defined through the corrosion-penetration-damage (μm) diagram obtained for the specimen. Present work positions INESSCOM as an innovative support to structural health monitoring strategy in UHPFRC structures. © 2022 The Authors. Structural Control and Health Monitoring published by John Wiley & Sons Ltd.