A recent study conducted by researchers from Rice University has revealed that a coal-based product called graphene could serve as a replacement for sand in concrete. Concrete, the second most consumed material in the world, is causing an environmental crisis due to the unsustainable rates of sand mining. The study, published in ACS Applied Materials & Interfaces, demonstrates that concrete made with a graphene substitute is 25% lighter but just as tough as traditional concrete.
The global demand for concrete is projected to increase significantly, with 68% of the population expected to reside in urban areas by 2050. However, this high demand comes at a cost. Cement production, a key ingredient in concrete, is responsible for 8% of global carbon dioxide emissions. Additionally, unregulated sand mining poses serious threats to river and coastal ecosystems. These factors, combined with population growth and urban expansion, may soon lead to a sand crisis, according to a United Nations report.
Rice University’s research team used their signature joule-heating technique to convert metallurgical coke into graphene, which can then be used as a substitute for sand in concrete. Initial experiments showed that the graphene derived from metallurgical coke was similar in size to sand. Encouraged by these results, the team explored the use of metallurgical coke-derived graphene as a total replacement for sand in concrete, finding that it performed exceptionally well.
Tests comparing graphene-based concrete with conventional concrete demonstrated that the former not only matched the mechanical properties of traditional concrete, but also offered a higher strength-to-weight ratio. The researchers used Flash Joule heating, a technique they have previously employed for various applications, to produce graphene more efficiently and on a larger scale than existing methods.
While the cost of graphene is currently a limiting factor, the new technology shows promise in reducing reliance on natural sand and lowering carbon emissions from the concrete industry. Satish Nagarajaiah, a professor of civil and environmental engineering who contributed to the study, emphasized that sand constitutes 30% of concrete. By using metallurgical coke as a substitute for sand, not only can high-quality concrete be produced, but significant cost savings can also be achieved, as metallurgical coke costs around 10% of the price of concrete.
James Tour, a professor at Rice University, acknowledged that it may take some time for the price of graphene to decrease to a level where it becomes economically viable. However, he expressed optimism about the potential alternatives that can be pursued to address the growing sand crisis and promote more sustainable urban development practices.
The findings of this study provide a glimmer of hope for the concrete industry, suggesting that coal-based graphene could play a crucial role in solving the environmental and resource challenges associated with sand mining. As further research and development is conducted, the widespread adoption of graphene in concrete production could lead to a more sustainable and eco-friendly future.
