Nanjing Researchers Unveil Breakthrough in Sustainable Maritime Concrete

In a recent study published in the journal ‘Scientific Reports’ (translated from Chinese as ‘Scientific Reports’), researchers led by Yuhua Wang from the School of Electricity and Engineering at Nanjing Vocational Institute of Railway Technology have shed light on the behavior of alkali-activated concrete (AAC) under harsh conditions. The research focused on how this innovative material performs under triaxial compression and freeze-thaw cycles, which are particularly relevant to maritime and cold-region applications.

So, what’s the big deal about AAC? Well, it’s a more sustainable alternative to traditional concrete, made by using industrial by-products like fly ash and slag. But before we can widely adopt it in places like ports, offshore structures, or cold climates, we need to understand how it behaves under stress and extreme weather conditions.

The team subjected cylindrical AAC specimens to various confining pressures (0, 3, and 6 MPa) and up to 200 freeze-thaw cycles. They found that increasing confining pressure changes the failure mode from tensile cracking to shear-compression failure, significantly boosting the load-bearing capacity. “Increasing confining pressure changes the failure mode from tensile cracking to shear-compression failure, significantly improving load-bearing capacity,” Wang noted.

However, the number of freeze-thaw cycles took a toll on the material’s peak strength and elastic modulus. The most severe degradation was observed at 3 MPa, but a confining pressure of 6 MPa effectively mitigated this deterioration. Based on their findings, the researchers proposed predictive models for the triaxial compressive strength and elastic modulus after freeze-thaw cycles, as well as a constitutive model to describe the stress-strain relationship.

For the maritime industry, these findings are a big deal. Ports, offshore platforms, and other coastal structures are often exposed to harsh environments, including freezing temperatures and saltwater exposure, which can lead to freeze-thaw cycles. Understanding how AAC behaves under these conditions can help engineers design more durable and sustainable structures.

Moreover, the use of AAC can reduce the carbon footprint of these structures, as the production of traditional concrete is a significant source of greenhouse gas emissions. By adopting AAC, the maritime industry can contribute to global efforts to reduce emissions and combat climate change.

In summary, this research provides valuable insights into the behavior of AAC under triaxial compression and freeze-thaw cycles. The findings offer a promising path forward for the maritime industry, enabling the design of more durable, sustainable structures that can withstand harsh environments. As Wang puts it, “These findings enhance understanding of AAC durability and provide design references for its application in cold regions and harsh environments.”

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