Aging infrastructure globally faces degradation, posing risks and requiring substantial repair investment. Strategic maintenance practices are crucial for evaluating structural conditions and ensuring sustainability. The growing demands on modern materials and structures necessitate enhanced health monitoring approaches. Shifting from reactive to proactive maintenance methodologies is paramount, due to lower investment while keeping the structural performance at acceptable standards. However, quantitative assurance of repair/reinforcement/retrofit programs or self-healing effect in structures is similarly crucial for the operation of the infrastructure. Non-destructive testing (NDT) techniques, such as ultrasound, acoustic emission, and optical methods, play a vital role in assessing structural health. Through real-world case studies, the effectiveness of repair in addition to damage assessment are evaluated, encouraging a more systematic approach to monitoring structural repair efficacy. The paper intends to address the research gap in monitoring the repair effectiveness in civil structures and materials and provides valuable insights to enhance repair strategies in civil engineering.

This paper presents a comparative study based on a thorough beam bending test.The intention is to obtain the relationship between the nominal elastic wave velocity obtained from Acoustic Emission tomography analysis and the physical damage of the RC beam in terms of crack opening. The crack width of the specimen was determined by both Digital Image Correlation and the conventional LVDT measurements. The study shows that globally the nominal wave speed derived from AE tomography is related to the crack development of the specimen when the crack width is limited. It is also shown that the scatter of the AE tomography results can be improved by averaging the nominal wave velocity of the cells along the cracked section.