The collapse of various civil engineering structures-such as bridges, dams, and buildings-has become a common occurrence in recent years, often attributed to aging and material degradation (refer to relevant news reports). Many of these structures were constructed decades ago, with assumed service lives typically ranging from 50 to 80 years. For instance, the design life of bridges is often considered to be around 50 years, while that of dams can extend to 100 years or more.
In general, concrete structures can remain operational well beyond their intended service life, especially with regular maintenance and repair. However, the conventional practice of evaluating structural integrity through visual inspections alone is inadequate. Surface-level cracks are often seen as the primary indicators of structural failure, but this assumption can be dangerously misleading. In reality, severe internal degradation can occur without visible signs. For example, the leaching of calcium silicate hydrate (C-S-H) gel and the subsequent removal of salts from the surface can undermine the concrete’s mechanical strength. Similarly, reinforcement corrosion may advance significantly without any external manifestation.
These hidden deteriorations, coupled with the lack of advanced structural health monitoring systems, may lead to a sudden and unexpected collapse. In some cases, aged structures already weakened by decades of service are subjected to loads beyond their residual capacity, resulting in catastrophic failure-such as the reported collapse of bridges along the Trans-Siberian Highway in Russia.
Safety, defined as the condition of being protected from or unlikely to cause danger, risk, or injury, must be reassessed in the context of aging infrastructure. This article focuses on the safety of deteriorated structures nearing or exceeding their service life, where original safety margins and design assumptions may no longer be applicable.
Bridge failure due to deterioration
The collapse of concrete bridges due to structural deterioration presents a significant concern in the field of civil engineering, emphasizing the critical need for continuous monitoring, preventive maintenance, and the reassessment of design assumptions over time. Deterioration is not a sudden event but rather a gradual process influenced by environmental exposure, aging materials, insufficient maintenance, and, in some cases, flawed retrofit interventions. As infrastructure worldwide continues to age, the risk of structural failure due to deterioration grows, necessitating a deeper understanding of failure mechanisms and proactive management strategies.
Segmental Post-Tensioned Concrete Bridge Collapse (1985)
One of the most instructive examples of a collapse resulting from material degradation is the failure of a segmental post-tensioned concrete bridge in 1985. Originally constructed in 1953, this bridge collapsed abruptly and without any visible signs of prior distress. Subsequent investigation revealed that the tendons embedded at the segmental joints had suffered from severe corrosion, primarily due to chloride intrusion. The chlorides likely originated from de-icing salts or dune sand incorporated into the mortar. This deterioration compromised the post-tensioning system’s capacity, ultimately leading to structural failure. The case highlighted the vulnerability of post-tensioned systems to corrosion and raised widespread concerns about the durability of similar bridges in service (Woodward, 1989).
The Koror-Babeldaob Bridge Failure
The Koror-Babeldaob Bridge, another notable case, collapsed due to delamination of the top flange induced by excessive compressive stress. A mid-life retrofit, intended to correct mid-span sagging, inadvertently altered the bridge’s stress profile. The retrofit eliminated the central hinge and increased the top flange compression without providing sufficient transverse reinforcement. As a result, delamination progressed until the structural integrity of the bridge was entirely lost. This incident underscored the potential risks of structural retrofitting without thorough stress analysis and demonstrated how well-intentioned interventions can lead to catastrophic outcomes when secondary effects are overlooked (Klein, 2008).
Mechanisms of Deterioration in Reinforced Concrete Bridges
A wide body of research confirms that reinforced concrete bridges are subject to multiple deterioration processes that, if left unmitigated, can culminate in collapse. These include reinforcement corrosion, shrinkage-induced cracking, alkali-silica reaction (ASR), freeze-thaw cycles, fatigue under repetitive loads, and the leaching of calcium silicate hydrate (C-S-H) gel. Environmental conditions such as marine exposure, the use of de-icing salts, and industrial pollution further exacerbate these mechanisms. Importantly, many of these degradation processes are internal and may not be visible from surface inspections. Without advanced monitoring technologies, the residual strength of aging structures may remain overestimated, posing latent risks (Lin, 2019; Stoilova, 2024).
Additional Notable Incidents
Beyond the aforementioned cases, numerous other structural failures have been linked to deterioration-related factors, both in bridges and other concrete structures. For example:
- Champlain Towers South, Florida (2021): Although an apartment complex, the collapse was attributed to concrete deterioration, emphasizing the broader relevance of material aging across civil structures (Li, 2023).
- I-35W Mississippi River Bridge, Minneapolis (2007): The collapse was associated with the corrosion of gusset plates and inadequate load-bearing design, exacerbated by overloading during maintenance activities (Salem et al., 2013).
- Silver Bridge, West Virginia (1967): This bridge collapsed due to corrosion-induced failure of an eyebar connection, a singular point of vulnerability that led to total failure (Stoilova, 2024).
- Mianus River Bridge, Connecticut (1983): The collapse was caused by the failure of a deteriorated pin connection, again pointing to the dangers of aging mechanical components in bridge structures (Stoilova, 2024).
- Tsing Ma Bridge, Hong Kong: Although still operational, environmental exposure has necessitated repeated interventions to counteract ongoing deterioration (Stoilova, 2024).
- Tacoma Narrows Bridge, Washington (1940): While the original collapse was due to aerodynamic instability, subsequent iterations have shown vulnerability to environmental deterioration requiring significant maintenance (Stoilova, 2024).
- Cypress Street Viaduct, Oakland (1989): The structure failed during the Loma Prieta earthquake, with post-event analysis revealing that pre-existing concrete degradation and inadequate design amplified the collapse risk (Mahdi & Mohammed, 2024).
- Kintai Bridge, Japan: Though largely made of wood, the bridge’s historical collapse and eventual reconstruction illustrate the broader issue of environmental degradation and the need for long-term preservation planning (Stoilova, 2024).
- Sampoong Department Store, South Korea (1995): While a building rather than a bridge, this case demonstrated how concrete deterioration and poor construction oversight can lead to deadly structural failures (Li, 2023).
Dam failure due to deterioration
The structural integrity of dams is of paramount importance due to the high risk associated with their failure. While dams are typically designed for long-term operation-often exceeding 100 years-their performance can be severely undermined by material deterioration, particularly in concrete components. Concrete degradation in dams is often subtle and progressive, yet it can culminate in catastrophic collapse. This essay examines notable cases where concrete deterioration played a key role in dam failure or decommissioning, including the Huangbizhuang Reservoir auxiliary dam, Raystown Dam, and Alto Ceira Dam. Each case underscores distinct mechanisms of deterioration and the broader implications for dam safety and resilience.
Huangbizhuang Reservoir Auxiliary Dam (China)
The auxiliary dam of the Huangbizhuang Reservoir presents a critical case of foundation and concrete deterioration. Multiple collapses were recorded over time, primarily due to foundation instability linked to the presence of solution caverns and liquefiable sand layers. These geotechnical vulnerabilities undermined the dam’s structural support, but concrete deterioration further compounded the risk. Specifically, the concrete cutoff wall-designed to prevent seepage-suffered progressive degradation, particularly through the loss of jointing materials. This mass loss weakened the structural cohesion of the wall, enabling seepage paths that ultimately contributed to failure (刘杰, n.d.). The case highlights the importance of integrating geotechnical assessments with long-term concrete performance monitoring in dam safety protocols.
Raystown Dam (United States)
The Raystown Dam in Pennsylvania offers a compelling example of chemical deterioration of concrete, particularly in hydraulic structures exposed to aggressive water environments. In the spillway’s warm-water chute, rapid concrete degradation was observed. The deterioration was driven by chemically aggressive water that dissolved the cement paste and attacked the aggregates, leading to disintegration of the concrete matrix. Notably, the presence of interconnected voids within the concrete allowed water to infiltrate and propagate internal damage, significantly reducing the structural integrity of the chute walls. This case illustrates the dangers of unchecked water-chemistry-induced degradation and the importance of material selection and protective coatings in dam design and maintenance (Holland et al., 1980).
Alto Ceira Dam (Portugal)
The Alto Ceira Dam in Portugal was ultimately decommissioned due to severe concrete deterioration caused by alkali-silica reaction (ASR). The aggregates used in the dam’s construction were highly susceptible to ASR, a chemical reaction between reactive silica in the aggregates and alkalis in the cement. This reaction resulted in the formation of an expansive gel that caused internal cracking, swelling, and loss of mechanical strength. Over time, these effects led to unacceptable structural risks, prompting the replacement of the dam in 2014 (Custódio et al., n.d.). The Alto Ceira case underscores the long-term consequences of inadequate materials testing and the necessity of ASR mitigation strategies in dam engineering.
Concrete deterioration poses a critical threat to the safety of residential structures, often leading to partial or complete building collapse. While such failures are typically associated with poor construction practices or natural disasters, underlying material degradation-particularly in reinforced concrete-plays a pivotal role. This essay examines several prominent cases where deterioration contributed to residential building collapse, alongside an analysis of the key mechanisms driving these failures.
Champlain Towers South Collapse (Florida, USA)
One of the most tragic examples of residential collapse in recent history occurred in June 2021 with the failure of the Champlain Towers South condominium in Surfside, Florida. The investigation into the disaster revealed extensive concrete deterioration, including spalling, exposed and corroded reinforcement bars, and long-deferred repairs. Structural reports prior to the collapse had warned of significant degradation in the building’s concrete elements, especially in the pool deck and parking garage areas. The corrosion of reinforcing steel, driven by prolonged exposure to moisture and chloride ingress, had compromised the load-carrying capacity of critical components. The case exemplifies the fatal consequences of neglecting routine maintenance and highlights the necessity of early intervention in aging residential infrastructure (Li, 2023).
Pyrrhotite-Induced Foundation Deterioration (Connecticut, USA)
In Eastern Connecticut, thousands of homes have been affected by premature concrete deterioration due to the presence of pyrrhotite in aggregate materials used in foundation construction. Pyrrhotite, an iron sulfide mineral, reacts with oxygen and moisture, leading to internal expansion, cracking, and progressive weakening of the concrete. Although the deterioration may take years to manifest, it ultimately results in severe structural instability and renders affected homes uninhabitable. This case has prompted widespread concern over aggregate sourcing and the long-term durability of residential concrete, as well as legal and financial challenges for homeowners (Zhong & Wille, 2018).
Van-Ercis Earthquake Collapse (Turkey, 2011)
The 2011 Van-Ercis earthquake in eastern Turkey exposed serious vulnerabilities in reinforced concrete buildings, particularly in the residential sector. Numerous structures collapsed during the seismic event, and post-disaster assessments attributed the failures to both poor construction practices and the degraded condition of the concrete. Low-quality materials, inadequate reinforcement, and insufficient curing processes had resulted in brittle and porous concrete that was unable to withstand seismic forces. This event underscores the compounded risks of material deterioration in earthquake-prone regions and the importance of enforcing construction standards (Çelebi et al., 2013).
Underlying Causes of Concrete Deterioration in Residential Structures
Several interrelated factors contribute to the deterioration of concrete in residential buildings:
Corrosion of Reinforcement Steel: One of the most critical degradation mechanisms is the corrosion of embedded steel reinforcements. This typically results from chloride ingress or carbonation, which disrupts the passive protective layer around steel bars. As corrosion products expand, they exert tensile stresses on surrounding concrete, leading to cracking, delamination, and spalling. Over time, this compromises the structural capacity of the affected elements (“Editorial,” 2023).
Environmental and Climatic Factors: Climate change and urbanization have intensified exposure to aggressive environmental conditions such as humidity, freeze-thaw cycles, acid rain, and de-icing salts. These factors accelerate chemical and physical deterioration processes in concrete, increasing the vulnerability of residential buildings, especially those not designed for such conditions (Breysse, 2010).
Material Deficiencies and Construction Defects: The use of poor-quality materials, improper mix design, and inadequate curing practices can produce low-durability concrete prone to early deterioration. In addition, construction errors-such as insufficient cover to reinforcement or poor compaction-can create vulnerabilities that magnify over time.
References
- Stoilova, V. (2024). Reinforced concrete bridges deterioration processes: A review. World Journal of Advanced Engineering Technology and Sciences. https://doi.org/10.30574/wjaets.2024.13.2.0525
- Lin, C.-S. (2019). Deterioration Effects on Progressive Collapse of Bridges. https://doi.org/10.7916/D8-2CDC-JA95
- Li, S. (2023). Failure in concrete and methods to improve the performance. Advances in Engineering Technology Research. https://doi.org/10.56028/aetr.8.1.537.2023
- Klein, G. (2008). Collapse of the Koror-Babeldaob Bridge. 17, 98-99. https://doi.org/10.2749/222137908796291976
- Woodward, R. J. (1989). Collapse of a segmental post-tensioned concrete bridge. Transportation Research Record, 1211. https://trid.trb.org/view/308412
- Mahdi, L. S., & Mohammed, H. A. (2024). State of Art: Seismic Failure Impact on Concrete Bridges. Academic International Journal of Engineering Science, 2(02), 01-08. https://doi.org/10.59675/e221
- Salem, H., Helmy, H., & El Fouly, A. (2013). Prediction of Bridge Behavior Through Failure: A Case Study Of The Minnesota I-35W Bridge Collapse. 2904-2915. https://doi.org/10.1061/9780784412848.253
- Breysse, D. (2010). Deterioration processes in reinforced concrete: an overview (pp. 28-56). Woodhead Publishing. https://doi.org/10.1533/9781845699536.1.28
- Çelebi, E., Aktas, M., Caglar, N., Özocak, A., Kutanis, M., Mert, N., & Özcan, Z. (2013). October 23, 2011 Turkey/Van-Ercis earthquake: structural damages in the residential buildings. Natural Hazards, 65(3), 2287-2310. https://doi.org/10.1007/S11069-012-0478-9
- Zhong, R., & Wille, K. (2018). Deterioration of residential concrete foundations: The role of pyrrhotite-bearing aggregate. Cement & Concrete Composites, 94, 53-61. https://doi.org/10.1016/J.CEMCONCOMP.2018.08.012
- Li, S. (2023). Failure in concrete and methods to improve the performance. Advances in Engineering Technology Research. https://doi.org/10.56028/aetr.8.1.537.2023
- Custódio, J., Mata, J., Serra, C., Bettencourt Ribeiro, A., Tavares de Castro, A., & Batista, A. (n.d.). Insights into the Diagnosis and Prognosis of the Alkali-Silica Reaction (ASR) in Concrete Dams, Highlighting the Case of the Demolished Alto Ceira Dam in Portugal. https://doi.org/10.3390/buildings15030460
- 刘杰. (n.d.). Collapse Causation Analysis of the Auxiliary Dam of Huangbizhuang Reservoir. https://doi.org/10.3969/j.issn.1009-640x.2003.04.004
- Holland, T. C., Husbands, T. B., Buck, A. D., & Wong, G. S. (1980). Concrete Deterioration in Spillway Warm-Water Chute, Raystown Dam, Pennsylvania. Defense Technical Information Center. https://apps.dtic.mil/sti/pdfs/ADA094246.pdf
