Structural Health Monitoring of Corrosion-induced Damage Within Masonry Structures Using Non-Destructive Techniques

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Degradation due to corrosion costs the UK economy £24 billion annually, equal to 1.6% of the GDP and is thus important to research to minimise disruption both to the economy and our built infrastructure. Masonry buildings built between the 18th and 20th centuries were typically built with metallic components such as cramps, dowels, ties, etc. as the structural integrity of these masonry walls are highly dependent on these embedded elements Where adequate corrosion protection had not been considered by architects, it is now imperative to ensure that corrosion of these embedded metals is avoided. This is because once corroded, the oxide products will typically occupy a volume 7-12 times greater than the original metal. This creates a force which has the potential to jack open and destroy the surrounding mortar and stone/bricks of masonry structures from the inside out, giving this phenomenon the name of oxide jacking. Corrosion of embedded metals is likely to increase within masonry structures in the future, caused by increases in rainfall, temperatures, and wind speeds due to climate change. It is therefore important to detect the location and extent of corrosion of metallic elements embedded within masonry structures, without having to damage or dismantle the structure.To date, research on this topic has been heavily focussed on applications of non-destructive techniques to detect corrosion-induced damage within 20th and 21st century reinforced concrete structures. My thesis will utilise recent advances in techniques used with reinforced concrete and extend and refine their use with masonry constructions. Using a combination of laboratory testing and on-site application, a range techniques will be developed for both one-off and continuous monitoring of corrosion-induced damage in masonry buildings. Such a methodology will, in time, lead to enhanced ability to determine the location and extent of corrosion can be determined, thereby improving the evidence base for maintenance. The overall aim of this project is to evaluate the use of non-destructive techniques for structural health monitoring in identifying and monitoring corrosion of metallic components within 18th to 20th century masonry buildings. A range of non-destructive techniques, such as, but not limited to, acoustic emission testing and micro computed tomography, will be investigated for their suitability to detect and determine signals produced by the corrosion of embedded metallic components in masonry structures, and any subsequent damage, such as cracking, which occurs in the surrounding mortar and stone/brick. These techniques have been successfully utilised for reinforced concrete structures but have hitherto never been applied to masonry structures, and thus there is the potential to investigate whether they could be useful techniques for new applications. This project falls under the wider EPSRC Engineering Research Area, with more specific emphasis on the Structural Engineering, and Built Environment Research Areas.