Concrete sleepers are essential components of railroad infrastructure, yet their service life has been reduced by one-third due to deterioration caused by internal swelling reactions (ISR), leading a major Brazilian railroad to replace millions of sleepers within a decade. This study investigates the reliability of various non-destructive testing (NDT) techniques to estimate damage levels in concrete sleepers. The methods evaluated include surface hardness testing, stress wave propagation, electromagnetic wave propagation using ground-penetrating radar (GPR), electrical resistivity, and resonant frequency. These techniques were applied to assess sleepers diagnosed as affected by alkali-silica reaction (ASR) and delayed ettringite formation (DEF) at different deterioration degrees. Although findings indicate that most NDT methods are limited and unreliable for quantifying ISR-induced damage, resonant frequency testing combined with energy dissipation analysis provided the highest accuracy across all damage stages and was able to capture microstructural changes before significant expansion occurred. These results support the use of vibration-based screening tools to enhance early detection and guide condition assessment of railroad infrastructure, helping to reduce the premature replacement of ISR-affected concrete sleepers.

Prestressed concrete railroad ties are the global standard for railway infrastructure due to their structural stability, durability, and cost-effective maintenance. However, their long-term performance is often compromised by premature deterioration. This study investigates the degradation of prestressed concrete railways ties from a Brazilian rail line after ten years of natural exposure, emphasizing critical implications for infrastructure maintenance. Two groups of ties, separated by 30 km, were analyzed through physical property assessments, petrography, X-ray diffraction (XRD), and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS). The results reveal that deterioration was driven by the combined effects of alkali–silica reaction (ASR) and sulfate attack, confirmed by the presence of (N, C)ASH gels, ettringite crystallization, and cryptocrystalline materials within cracks and voids. Prestressing-induced stresses and environmental moisture further accelerated degradation, leading to a 66% reduction in mechanical strength in the T1 group. These findings demonstrate that internal swelling reactions and moisture exposure synergistically accelerate deterioration in prestressed concrete ties, particularly in low-prestress, poorly drained zones.

A partir de ensaios não destrutivos (ENDs), é possível a obtenção de características dos materiais, de forma não invasiva e sem causar danos ao elemento analisado. No entanto, os resultados obtidos são qualitativos, sendo necessárias correlações por meio de ensaios destrutivos em amostras do material. Assim, o objetivo do presente estudo é correlacionar os parâmetros obtidos nos ensaios não destrutivos, realizados em uma viga tipo I de concreto protendido, com ensaios de resistência à compressão em corpos de prova obtidos do mesmo lote de concreto. O programa experimental foi realizado por meio dos ensaios de dureza superficial (esclerometria), velocidade de ultrassom e módulo de elasticidade dinâmico, em diferentes idades. Os ensaios foram realizados 24 horas e 7 dias após a moldagem. Para a obtenção das correlações, foram realizados ensaios resistência à compressão nos corpos de prova cilíndricos, nas mesmas idades de realização dos ensaios não destrutivos. Como resultado, não foram obtidos valores apropriados de correlação dos parâmetros de ENDs com os resultados mecânicos, sendo necessários mais estudos para a viabilização dos ensaios não destrutivos como ferramenta de controle de produção de vigas protendidas nas primeiras idades.