The overreliance on concrete, the world’s second most utilized substance after water, presents an environmental and resource dilemma, exacerbated by sand mining rates surpassing natural replenishment levels.
In a groundbreaking study published in the journal ACS Applied Materials & Interfaces, researchers from Rice University propose a novel solution: utilizing graphene derived from metallurgical coke, a coal-based product, not only as a reinforcing agent but also as a substitute for sand in concrete.
James Tour, Rice’s distinguished T. T. and W. F. Chao Professor, highlighted the potential impact of this innovation: “This could revolutionize one of the largest industries globally. Our comparison between conventional concrete and graphene-infused concrete revealed a 25% reduction in weight without compromising toughness.”
Concrete, comprising aggregates like sand and gravel bound by cement and water, serves as a cornerstone for urbanization. With an estimated 68% of the global population projected to reside in urban areas by 2050, the demand for concrete and consequent sand mining is anticipated to surge. In the last two decades alone, sand mining has tripled, reaching approximately 50 billion tons annually, exacting a heavy toll on the environment.
Cement production, integral to concrete, contributes to 8% of global carbon dioxide emissions. Furthermore, unregulated sand mining poses dire threats to river and coastal ecosystems. According to a 2022 United Nations report, this escalating demand for sand, coupled with population growth and urban sprawl, could precipitate a “sand crisis.”
Leveraging their innovative joule-heating technique, the Tour lab transformed metallurgical coke into graphene, resembling sand in size and texture. Paul Advincula, a lead author on the study, elaborated on their findings: “Our experiments demonstrated the feasibility of using metallurgical coke-derived graphene as a complete replacement for sand in concrete, offering excellent results.”
Comparative tests between conventional concrete and graphene-infused concrete showcased promising outcomes. Not only does graphene-based concrete match the mechanical properties of standard concrete, but it also exhibits a higher strength-to-weight ratio.
The Tour lab’s Flash Joule heating method has found diverse applications, from hybrid carbon nanomaterial synthesis to battery part recycling and coal fly ash heavy metal removal.
“While the viability of this technology hinges on graphene’s eventual cost reduction, it underscores the pursuit of alternatives,” Tour emphasized.
Satish Nagarajaiah, a corresponding author on the study and professor of civil and environmental engineering and mechanical engineering, emphasized the significance of sand in concrete composition.
“As we teeter on the brink of a ‘sand crisis,’ exploring alternatives becomes imperative. Metallurgical coke, priced comparably to sand yet at 10% of concrete cost, not only enhances concrete quality but also promises substantial savings,” Nagarajaiah affirmed.
The potential to diminish reliance on natural sand and mitigate carbon emissions from the concrete industry heralds a more sustainable approach to urban development.
Source: Rice University