Structures built for residential, commercial, industrial, or other purposes primarily rely on a cementitious matrix reinforced with steel. While such structures offer durability, stability, and ease of maintenance, they also have inherent limitations, particularly in resisting adverse atmospheric and environmental conditions. These limitations become more pronounced in coastal areas due to continuous exposure to harsh elements.
Coastal environments present unique challenges that significantly impact the longevity and performance of structures. The primary factors contributing to structural deterioration in these regions include sea salinity, high humidity, and thermal variations. Understanding these challenges is essential for designing, constructing, and maintaining structures that can withstand such conditions over their intended service life.
Environmental Factors Affecting Coastal Structures
Impact of Sea Salinity
One of the most important concerns for coastal structures is the presence of sea salinity in the environment. Sea air carries chlorides and other salts, which have a highly corrosive effect on both cementitious materials and steel reinforcements. These salts react with concrete, leading to a gradual loss of structural integrity.
Steel reinforcements embedded in concrete are particularly vulnerable to chloride-induced corrosion. Once corrosion initiates, the expansion of rust exerts tensile stresses on the surrounding concrete, leading to cracking, spalling, and eventual structural deterioration. Additionally, the reaction between chlorides and the cement matrix results in a process known as de-polarization [Details of this phenomena will be discussed in later parts of this knowledge sharing series on the subject of “Challenges for coastal area structures”], where the homogeneity of the concrete is compromised, making it more susceptible to further degradation.
Since sea salinity is an ever-present factor in coastal environments, structures in these regions require additional protective measures to mitigate its long-term effects.
Role of High Humidity
Coastal areas experience consistently high humidity levels due to their proximity to large water bodies. Humidity plays a dual role in accelerating structural deterioration:
- Corrosion of Steel Reinforcement – The combination of high moisture content and chloride presence creates ideal conditions for corrosion, leading to reduced load-bearing capacity of reinforced structures.
- Cementitious Matrix Degradation – High humidity accelerates chemical reactions within concrete, including carbonation, which weakens its overall strength. Additionally, moisture penetration increases the risk of alkali-silica reactions, further compromising durability.
Humidity also acts as a catalyst in the de-polarization process, enhancing the rate at which cementitious materials lose their structural cohesion. The constant exposure to humid conditions makes it imperative to incorporate moisture-resistant construction techniques in coastal structures.
Effects of Thermal Variations
Coastal structures experience continuous thermal fluctuations due to varying day and night temperatures. These thermal cycles, which change with seasonal variations, result in expansion and contraction of materials. Over time, this repeated movement can cause:
- Micro-cracking in Concrete – Small cracks can develop and gradually widen, providing pathways for moisture and chlorides to penetrate deeper into the structure.
- Structural Fatigue in Steel Elements – Expansion and contraction cycles exert stress on steel components, leading to fatigue-related failures if not adequately addressed.
Thermal variations, in conjunction with high humidity and salt exposure, create a compounded effect that accelerates the degradation process in coastal structures.
Ensuring Structural Longevity in Coastal Environments
To ensure the designed functional life of coastal structures, it is important to adopt a proactive maintenance approach. Taking special care during their construction, Periodic inspections, condition monitoring, and preventive maintenance strategies help mitigate long-term damage. Additionally, advancements in material science and innovative construction techniques continue to play a key role in enhancing the sustainability and resilience of coastal infrastructure.
Conclusion
Ensuring the longevity of coastal structures requires a well-planned approach that considers the impact of salinity, humidity, and temperature variations. By using durable materials, adopting resilient design strategies, and implementing regular maintenance, these challenges can be effectively managed, reducing the risk of premature deterioration and costly repairs.
About the Author;
Er. Chirag K. Baxi is the Director of Prudent Forensic Consultancy Private Limited and General Manager of K K Retroflex Solutions. He specializes in Corrosion Control Measures for concrete and steel surfaces, Damage assessment with the FORENSIC ENGINEERING approach and Structural rehabilitation of concrete and steel structures in the Industrial environment. He holds a degree in BE (Civil Engineering) and has completed MBA (Construction Management).
The author has invented CONCARE B 14 (which has been granted a patent) that makes concrete structures sustainable even with salty, saline, untreated or even seawater without deterioration in any of the end properties of constructed elements. He has written (two) drafts of IS Codes on the topic of “Carbon brick lining” and “PolyPropylene Glass lining” which are under the final stage of approval at BIS.
About 40 Technical papers on National and International platforms are authored, published and presented by the author. He has been recognized by several Institutes for his significant contribution to the Civil Engineering Industry.
