In the quest for sustainable construction materials, a team of researchers from The Hong Kong Polytechnic University has made a significant breakthrough that could reshape the future of alkali-activated materials (AAMs) and have profound implications for the energy sector. Led by Dr. Yubo Sun from the Department of Civil and Environmental Engineering, the study focuses on transforming municipal solid waste incineration (MSWI) fly ash into a viable supplementary precursor for AAMs through a process called accelerated carbonation.
The energy sector is increasingly looking for sustainable solutions to reduce its carbon footprint and reliance on traditional materials. As the supply of blast furnace slag (BFS), a key component in AAMs, declines due to increased scrap recycling and its use in the cement industry, the need for alternative precursors has become urgent. This is where Dr. Sun’s research comes into play.
MSWI fly ash, a byproduct of waste incineration, has long been considered a waste material with limited use. However, Dr. Sun and his team have shown that by treating MSWI fly ash with accelerated carbonation, it can be converted into a valuable resource. “The presence of slaked lime in MSWI fly ash makes it an excellent candidate for CO2 capture,” Dr. Sun explained. “After just 6 hours of accelerated carbonation, we observed a 67% increase in calcite content, significantly enhancing its potential as a supplementary precursor for AAMs.”
But the benefits don’t stop at sustainability. The accelerated carbonation process also significantly reduces heavy metal leaching, a critical concern for environmental safety. “We saw a remarkable decrease in the leachate of copper and lead, by 53.1% and 73.5%, respectively,” Dr. Sun noted. This makes the treated MSWI fly ash not only a sustainable option but also an environmentally safe one.
The team tested AAM mixtures with varying amounts of carbonated MSWI fly ash (CMFA). While the addition of CMFA slowed early structuration and altered fresh mixture properties, a 10% addition of CMFA achieved comparable 28-day strength to the reference mixture. Moreover, the heavy metal leachate from hardened mortars met environmental standards, confirming the viability of CMFA as a supplementary precursor.
The implications of this research are far-reaching. As the energy sector continues to seek sustainable and environmentally friendly solutions, the use of CMFA in AAMs could become a game-changer. It not only addresses the declining supply of BFS but also provides a sustainable use for MSWI fly ash, reducing waste and lowering the carbon footprint of construction materials.
The study, published in the journal ‘Developments in the Built Environment’ (translated to English as ‘Advances in the Built Environment’), opens up new avenues for research and development in the field of sustainable construction materials. As Dr. Sun puts it, “This research is just the beginning. There’s so much more we can explore and achieve with accelerated carbonation and alkali-activated materials.”
The energy sector is watching closely, and the future of sustainable construction materials looks brighter than ever. With continued research and development, we could see a significant shift towards more sustainable and environmentally friendly practices in the industry. The work of Dr. Sun and his team is a testament to the power of innovation and the potential it holds for shaping a greener future.