In the relentless battle against corrosion in reinforced concrete (RC) structures, a new study from Nanyang Technological University and Kajima Technical Research Institute Singapore (KaTRIS) has unearthed a critical factor that could reshape how we approach maintenance and longevity in tropical climates. The research, led by Li Soon Wan, delves into the often-overlooked interplay between temperature and pore saturation, revealing a stark reality: our current models may be vastly underestimating corrosion risks in hot, humid regions.
In Singapore, where temperatures regularly soar above 30°C, and humidity is a constant companion, RC structures from the 1960s and 1970s are particularly vulnerable to carbonation-induced corrosion. These structures, often built with lower-strength concrete, are now facing a silent enemy that threatens their long-term durability. The problem is exacerbated by a lack of understanding of how temperature and pore saturation work together to accelerate corrosion.
“We’ve known that both temperature and pore saturation play significant roles in corrosion,” explains Li Soon Wan, “but what we didn’t know was how they interact, especially in warmer climates. Our study aimed to fill that gap.”
The research team systematically varied temperatures from 0°C to 40°C and pore saturation levels from 60% to 100%, using a combination of electrochemical and non-destructive measurements to monitor corrosion rates. The findings were alarming: as temperatures rise, the minimum pore saturation threshold for severe corrosion decreases dramatically. This means that even at lower levels of moisture, concrete in hot climates can experience substantial corrosion.
For concrete with a water-to-cement ratio of 0.65, the study found that severe corrosion occurred at much lower pore saturation levels at higher temperatures. Even more concerning, the researchers discovered that temperature-dependent corrosion kinetics, rather than concrete drying, predominantly drive the corrosion process at higher temperatures.
“This has significant implications for our current models,” says Wan. “Many of our durability assessments rely on temperature-independent pore saturation thresholds, which may be significantly underestimating corrosion risks in hot climates.”
The commercial impact of this research is profound, particularly for the energy sector. As infrastructure ages and the demand for reliable energy infrastructure grows, the need for accurate predictive tools becomes increasingly urgent. The study’s findings could prompt a fundamental reassessment of how we evaluate and maintain RC structures in tropical regions. By understanding the true extent of corrosion risks, energy companies can better allocate resources for maintenance, extend the lifespan of critical infrastructure, and avoid costly repairs or replacements.
The study, published in the journal ‘Case Studies in Construction Materials’ (English translation of the journal name: 研究案例:建筑材料) provides a compelling argument for revisiting our current models and developing more accurate predictive tools. As Wan and his team have shown, the interaction between temperature and pore saturation is a critical factor that demands our attention. The implications for the construction and energy sectors are clear: it’s time to adapt our approaches to better reflect the realities of hot, humid climates.