The global dependence on concrete, which ranks as the most widely used material next to water, is precipitating an environmental dilemma and putting strain on resources due to the unsustainable extraction of sand, which is depleting faster than it can naturally replenish.
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Researchers from Rice University have discovered that graphene, produced from metallurgical coke—a byproduct of coal—could not only enhance the strength of cement but also replace sand in the composition of concrete.
This could have a major impact on one of the biggest industries in the world… We compared concrete made using the graphene aggregate substitute with concrete made using suitable sand aggregates, and we found our concrete is 25% lighter but just as tough.
James Tour, Rice’s T. T. and W. F. Chao Professor and a Professor of Chemistry, Materials Science and Nanoengineering
Concrete, which consists of aggregates such as sand and gravel mixed with cement and water, plays a crucial role in urban development.
With almost 70% of the population expected to live in municipal areas by as early as 2050, demand for sand mining and concrete is anticipated to surge. The demand for sand has already tripled over the past two decades, with annual consumption reaching approximately 50 billion tons, posing severe environmental challenges.
Cement production, essential to concrete, is responsible for a staggering 8% of global CO2 emissions. Furthermore, the unregulated extraction of sand is also detrimental to river and coastal ecosystems. As per a United Nations report, this escalating demand could soon trigger what they are calling a “sand crisis.”
Flash Joule heating (FJH)
To address these concerns, the team at Rice University has utilized their distinctive flash Joule-heating (FJH) technique on metallurgical coke to produce a form of graphene that has the potential to replace sand in the concrete production process.
Initial experiments where metallurgical coke was converted into graphene resulted in a material that appeared similar in size to sand… We decided to explore the use of metallurgical coke-derived graphene as a total replacement for sand in concrete, and our findings show that it would work really well.
Paul Advincula, a Rice doctoral Alumni and Lead Author of the Study
Comparative studies between traditional concrete and the new graphene-infused version have also shown encouraging outcomes, with the graphene-enhanced concrete matching or surpassing the strength and durability of standard concrete.
This technique produces graphene faster and at a larger scale than previous methods.
Paul Advincula, a Rice doctoral Alumni and Lead Author of the Study
The Rice University research team has previously applied this Flash Joule heating method to various projects, including the synthesis of hybrid carbon materials and environmental remediation efforts. Thuys, this breakthrough offers a path towards reducing the concrete industry’s environmental footprint and dependence on natural sand, paving the way for more eco-friendly construction practices.
However, Tour cautioned that the cost-effectiveness of using graphene in concrete on a large scale would require time, due to the current price of graphene. Yet, he affirmed the importance of exploring sustainable alternatives.
Satish Nagarajaiah, another key contributor to the research and a professor in civil and environmental engineering and mechanical engineering at Rice University, stressed the urgency of finding substitutes for sand, given its significant proportion in concrete and the looming sand crisis. He suggested that metallurgical coke could not only enhance concrete quality but also lead to considerable economic savings.
Cementing a Concrete Future
The feasibility of producing coal-based graphene (AC-FG) through FJH anthracite treatment is emphasized by the quick and straightforward synthesis process, along with the production of high-quality material. This innovative approach has the potential to convert inexpensive coal into valuable graphene materials, offering economic advantages and product benefits.
As we move forward, it is essential for professionals and industry experts to collaborate, conduct further research, and explore the practical implementation of this exciting development. The construction industry is on the cusp of a transformative change, and the utilization of coal-based products in concrete could help to shape its future in a sustainable and eco-friendly manner.
References and Further Reading
- Clark, S.C. (2024) Rice study shows coal-based product could replace sand in concrete, Rice News | News and Media Relations | Rice University. Available at: https://news.rice.edu/news/2024/rice-study-shows-coal-based-product-could-replace-sand-concrete
- Advincula, P.A. et al. (2024) ‘Replacement of concrete aggregates with coal-derived flash graphene’, ACS Applied Materials & Interfaces, 16(1), pp. 1474–1481. Available at: https://pubs.acs.org/doi/full/10.1021/acsami.3c15156
- Farge, E. (2024) Sand crisis looms as world population surges, U.N. warns. Available at: https://www.reuters.com/business/environment/sand-crisis-looms-world-population-surges-un-warns-2022-04-26/#:~:text=warns,-By%20Emma%20Farge&text=GENEVA%2C%20April%2026%20(Reuters),amid%20population%20growth%20and%20urbanisation. (Accessed: 29 January 2024).