Effectiveness of Non-destructive Testing Methods to Assess Concrete Sleepers Affected by Internal Swelling Reactions (ISR)

Concrete sleepers are facing premature failures in Brazil due to internal swelling reactions (ISR), a challenge that has compelled the replacement of over one million sleepers in a major Brazilian railroad, reducing their lifespan by 1/3. This study investigates four groups of sleepers at different ISR distress levels, employing various non-destructive testing (NDT) techniques. Additionally, specimens extracted from these sleepers were also subjected to thorough condition assessment (i.e., microscopic and mechanical) to estimate the degree of damage accurately. The results obtained indicate that while traditional NDT methods have limitations in assessing distinct damage degrees, a combination of surface resistivity and resonant frequency tests enhances the early detection of ISR damage. In conclusion, NDT methods have limited potential to aid routine inspection. Once potential damage is identified, it is essential to conduct comprehensive multi-level assessments to diagnose the damage (i.e., cause and extent), supporting the management of ISR-damaged sleepers.