Performance of Composite Materials in Corrosive Conditions

Composites have seen increased usage for reinforcement of metallic structures in structural, marine, and underground conditions. While the mechanical properties of composites have been investigated extensively, the performance of the entire metal-composite system has not been addressed with regard to corrosion of the substrate, water intrusion at the composite-metal interface, and adhesion loss on the metal surface or within the composite itself. In this work we have investigated the influence of corrosive environments on the performance of composite repair systems with specific case studies on pipelines. The influence of impacts and holidays has been studied for cathodically protected substrates. In addition, the effects of cathodic shielding, long term immersion, and soil corrosivity have been investigated by monitoring variables related to potential and conductivity of the electrolyte. By monitoring these variables, loss of adhesion and integrity in the composite-metal system is studied to inform users about long term performance and reliability.