ADVANCED MATERIALS & PROCESSES | JULY 2026 18 The iron bridge over the Mendoza River, Argentina, installed in 1890, has remained in service for more than a century under demanding environmental and operational conditions. Its persistence raises a key question: Why has its degradation not progressed to the extent typically expected for structures of this age? Originally conceived as a hybrid structure combining iron elements with hardwood components, the bridge soon exhibited significant structural instability, with pronounced vibrations reported during operation[1]. These issues led to a major redesign in 1898, when the structure was rebuilt as a fully metal bridge, establishing the configuration that largely defines it today (Figs. 1 and 2). Following this transformation, the bridge was subjected to a series of interventions throughout the 20th century. These actions, although differing in scope and execution, were primarily aimed at maintaining structural stability and ensuring continued service under progressively increasing operational demands. During this period, maintenance efforts focused predominantly on structural performance rather than corrosion control. This approach evolved significantly in the 1990s, when both corrosion protection and structural optimization were explicitly incorporated into the intervention strategy. Rehabilitation works included abrasive blasting, anticorrosive primers, and protective WHY HAS THIS IRON BRIDGE SURVIVED? A study of a bridge in Argentina shows that preservation strategies based on material compatibility, controlled repair procedures, and a deep understanding of historical metallurgy can significantly extend the service life of such structures. Patricia S. Carrizo,* Archaeometallurgy Area, Institute of Materials and Applied Technology (IMTECAP), National Technological University, Mendoza Regional Faculty, Argentina *Member of ASM International coatings, followed by a final finish. At the same time, advances in materials and engineering design enabled a substantial reformulation of the bridge deck—historically its most critical component. By incorporating supplementary beams and improving structural efficiency, the deck was made lighter Fig. 1 — Iron bridge over the Mendoza River. while maintaining or improving its resistance, addressing its long-standing vulnerability[2]. MATERIALS CHARACTERIZATION AND REPAIR The 2016 campaign marked the sixth major preservation effort since the bridge’s original installation. In this stage, the approach extended beyond struc- tural repair and coating appli- cation, incorporating a detailed evaluation of the material itself. Chemical composition analysis of the bridge indicated very low carbon content (approximately 0.05 wt%), consistent with wrought, along with the presence of nonmetallic inclusions associated with the original manufacturing process (Table 1). This Fig. 2 — Metal iron bridge, installed in 1890 and still in service.
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