In the quest to make cement production more sustainable, a groundbreaking study has emerged from the labs of the University of Oulu and the University of Leeds. Led by Elijah D. Adesanya, a researcher straddling both institutions, the study delves into the potential of co-calcination—a process that could revolutionize the way we produce supplementary cementitious materials (SCMs). The findings, published in a recent issue of Case Studies in Construction Materials, offer a glimpse into a future where the paper and cement industries collaborate to create more eco-friendly building materials.
At the heart of this research lies the co-calcination of kaolinitic clay and green liquor dreg (GLD), a waste product from the paper industry. By blending these materials at varying ratios and calcining them at different temperatures, Adesanya and his team aimed to produce a limestone calcined clay (LC2)-type SCM. The goal? To enhance the sustainability of cement production and reduce the environmental footprint of both industries.
The study explored the effects of co-calcination temperatures ranging from 600°C to 800°C and different blending ratios of GLD and kaolinitic clay. The results were promising. “We identified 700°C as the most effective co-calcination temperature,” Adesanya explained. “This temperature optimized the chemical reactivity of the LC2-type SCM, as determined by the rapid, relevant, and reliable (R3) testing.”
The phase assemblage and hydration process of composite cements, which included varying replacement ratios of the produced SCM, were also evaluated. X-ray diffraction and scanning electron microscopy revealed intriguing variations in the phase assemblage of these composite cements compared to the reference CEM I. Notably, the calcium carbonate from GLD and metakaolinite from the calcined clay contributed to the formation of carboaluminate, a compound that significantly lowers the porosity of the cement.
But the real test of any new cementitious material is its strength. The study found that the 7- and 28-day compressive strengths of mortars produced by replacing 15–30 wt% of the cement with this SCM were comparable to those of the CEM I reference mortar. This means that the new SCM could potentially replace a significant portion of traditional cement without compromising structural integrity.
The implications of this research are far-reaching. For the cement industry, this study opens the door to more sustainable practices by utilizing waste products from the paper industry. For the paper industry, it offers a new revenue stream and a way to reduce waste. “This research demonstrates the potential for industrial symbiosis between the paper and cement industries,” Adesanya noted. “By applying co-calcination, we can address challenges related to the utilization of GLD while producing a suitable kaolinitic clay-based SCM.”
The study, published in Case Studies in Construction Materials, is a testament to the power of interdisciplinary research. By bridging the gap between the paper and cement industries, Adesanya and his team have paved the way for more sustainable construction practices. As the world continues to grapple with the challenges of climate change, such innovations will be crucial in building a more sustainable future.
The research not only highlights the technical feasibility of co-calcination but also underscores the economic and environmental benefits. By reducing the need for virgin materials and utilizing industrial waste, this process could significantly lower the carbon footprint of the construction industry. Moreover, it opens up new avenues for collaboration between industries, fostering a more circular economy.
As we look to the future, the potential applications of this research are vast. From large-scale infrastructure projects to everyday construction, the use of co-calcined SCMs could become a standard practice. This shift would not only make the construction industry more sustainable but also more resilient, as it adapts to the challenges of a changing climate.
The study by Adesanya and his team is a beacon of hope in the quest for sustainable construction. By leveraging the strengths of different industries and technologies, we can build a future that is not only stronger but also greener. As the construction industry continues to evolve, the insights from this research will undoubtedly play a pivotal role in shaping its future.
