Electrochemical investigation of accelerated deterioration of concrete with iron-sulfide containing aggregates

Abstract

The present study advances the understanding of deterioration progress in concrete foundations containing iron-sulfide bearing aggregates through electrochemical accelerated testing, coupled with non-destructive damage evaluation. The method addresses the challenge of time constraints in conventional laboratory studies by expediting the iron-sulfide oxidation process and subsequent concrete deterioration mechanisms in a controlled environment. Concrete cylinders cast in the laboratory and cored from an affected foundation in the field were subjected to the acceleration method under varied applied voltage and electrolyte exposure. Samples with iron-sulfide aggregates showed field-typical signs of deterioration within days to weeks, while those without these aggregates did not exhibit any measurable damage. The deterioration progressed with increased exposure time and applied voltage, evidenced by visual observation, quantified by decreased resonance frequency and increased total crack length. Complemented by microstructural and phase analyses, the results showed the successful accelerated replication of pyrrhotite oxidation and subsequent concrete deterioration.