Recent research has unveiled a significant advancement in the recycling of mine tailings as a supplementary cementitious material, which could revolutionize the construction industry. Conducted by Godfrey Mawire from the School of Civil and Mechanical Engineering at Curtin University, alongside the Commonwealth Scientific and Industrial Research Organisation in Western Australia, this study delves into the mineralogy of tailings and its impact on the hydration behavior of Ordinary Portland Cement (OPC) blends.
The study highlights the intricate relationship between the mineral composition of mine tailings and the performance of cement. Utilizing advanced techniques like Quantitative X-ray diffraction (QXRD) and thermogravimetric analysis with mass spectrometry (TGA-MS), the researchers were able to identify how specific minerals, such as dehydroxylated Fe-chlorite and alunite, influence early-stage hydration. Mawire stated, “Understanding the hydration mechanisms allows us to optimize the use of mine tailings, turning a waste product into a valuable resource for construction.”
The findings indicate that tailings not only alter the heat flow profile during hydration but also affect the phase assemblage of the cured cement. The presence of slow-reacting minerals releases elemental species that integrate into the calcium silicate hydrate (C-S-H) phases, crucial for the strength and durability of cement. This means that by incorporating mine tailings, the construction sector could enhance the performance of concrete while simultaneously addressing the environmental challenges posed by mining waste.
With a low Ca/Si ratio of less than 1.3, the C-S-H formed in these blended cements can accommodate guest elements, which may lead to innovative material properties. The use of Correlative Electron Microscopy Automated Mineralogy (CEM-AM) allowed the researchers to map the distribution of these secondary C-S-H phases, providing deeper insights into the microstructural evolution of the cement paste.
The implications of this research extend beyond environmental benefits; they open new avenues for cost-effective construction materials. As the industry grapples with rising material costs and sustainability pressures, incorporating mine tailings could provide a dual solution—reducing waste and enhancing the performance of concrete. “This research not only paves the way for a circular economy in construction but also sets the stage for future innovations in material science,” Mawire added.
As the construction sector increasingly prioritizes sustainable practices, studies like this one, published in ‘Cleaner Materials’ (translated as “Materials Cleaner”), will play a pivotal role in shaping future developments. The potential for using mine tailings in cement production could lead to a significant shift in how construction materials are sourced and utilized, fostering a more sustainable and economically viable industry.
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