Detecting Corrosion of Steel Prestressing Strands Using Acoustic Emission

Abstract


 
 
 America’s transportation infrastructure has been receiving intensive public and private attention in recent years, particularly highway bridges. Corrosion of reinforcement steel is a main durability issue especially for concrete structures present in coastal areas and in areas where de-icing salts are routinely used.Acoustic emission (AE) is a promising method for detecting corrosion in steel reinforced concrete members. This type of non-destructive testing (NDT) method primarily measures the magnitude of energy released within a material when physically strained. The expansive ferrous product resulting from corrosion induces pressure at the steel-concrete interface creating micro-cracks which can be detected by AE sensors. In this study, five concrete blocks with embedded prestressing steel strands were built and tested under accelerated corrosion conditions to evaluate possible correlations between AE activity and the onset and progression of corrosion. AE data along with half-cell potential measurements were recorded during the test to determine the stages and the overall deterioration process. Afterwards, the steel strands were removed from the specimens, cleaned and weighed; then the results were evaluated vis-à-vis Faraday’s law with respect to the degree of corrosion present in each block.