Researchers have developed a novel “Deep Breathing Analogy” (DBA) method to improve the efficiency of carbon dioxide (CO2) capture in concrete. Inspired by the human breathing mechanism, the DBA method involves cyclically injecting pure CO2 into a reaction chamber (like inhaling) and then evacuating the gas (like exhaling). This process helps remove excess water from the concrete, allowing for deeper penetration of CO2 and more effective carbonation. The study found that the DBA method significantly outperforms conventional pressurized carbonation techniques, with the potential to generate millions in carbon credits annually from recycled concrete aggregates. This innovative approach could be a game-changer in the quest for more sustainable construction practices. Carbon capture and storage and concrete are key areas of research for reducing greenhouse gas emissions.
Breathing New Life into Concrete Carbonation
The construction industry has a significant environmental impact, responsible for around 10 gigatons of CO2 emissions annually. One promising strategy to reduce these emissions is to capture and store CO2 within concrete through a process called carbonation. This involves the reaction between CO2 and the cement hydration products, forming stable calcium carbonate (CaCO3).
However, the natural carbonation process in the environment is slow, prompting researchers to explore various accelerated carbonation methods. Pressurized carbonation, which involves injecting CO2 into concrete at higher-than-atmospheric pressures, has shown promising results in enhancing the efficiency of CO2 capture. But even these methods have their limitations, often struggling with issues like pore blockage and water accumulation.
Inhale, Exhale: The Deep Breathing Analogy
Inspired by the human respiratory system, a team of researchers has developed a novel “Deep Breathing Analogy” (DBA) method to address these challenges. The DBA process involves cyclically injecting pure CO2 into a reaction chamber (like inhaling) and then evacuating the gas (like exhaling). This cycle helps remove excess water from the concrete, allowing for deeper penetration of CO2 and more effective carbonation.
The researchers tested several variations of the DBA method, including adjusting the duration of the inspiration and expiration phases, as well as gradually increasing the pressure over successive cycles. The results were impressive – the DBA methods outperformed conventional pressurized carbonation techniques by a significant margin, with the most efficient version improving the proportion of CO2 captured by over 135%.
Unlocking the Economic Potential of Concrete Carbonation
The team also explored the economic potential of concrete carbonation, estimating that the full carbonation of annually produced construction and demolition waste could generate a staggering $14.5 billion in carbon credits. Even the more modest, 24-hour carbonation results of the DBA methods could still produce hundreds of millions in carbon credits, making this approach a financially attractive proposition.
Predicting the Future of Pressurized Carbonation
In addition to the experimental work, the researchers developed a new predictive model for pressurized carbonation, which incorporates the effects of temperature, compressive strength, and pressure. This model showed good agreement with the test data, providing a valuable tool for forecasting carbonation depth and guiding future research and applications.
A Breath of Fresh Air for Sustainable Construction
The Deep Breathing Analogy method represents a significant breakthrough in the quest for more efficient and sustainable concrete carbonation. By harnessing the power of cyclical CO2 injection and removal, this innovative approach could be a game-changer in reducing the environmental impact of the construction industry. As the world strives to achieve carbon neutrality, this research offers a promising path forward, breathing new life into the future of sustainable construction.
Author credit: This article is based on research by Ray Kai Leung Su, Hao Li, Lijie Chen, Hongniao Chen.
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