In the quest for sustainable construction materials, researchers have turned an eye towards an often-overlooked waste product: concrete slurry waste (CSW). A recent study led by Yuyun Gan from the Department of Civil Engineering at Universiti Malaya in Kuala Lumpur, Malaysia, has demonstrated the potential of recycling CSW into alkali-activated materials (AAMs), offering a promising avenue for reducing concrete waste and promoting greener construction practices.
Concrete slurry waste, accounting for approximately 0.8% of concrete production in ready-mix plants, has long posed environmental challenges. Gan’s study, published in *Case Studies in Construction Materials* (translated as “Case Studies in Building Materials”), explores the use of CSW as a precursor material in AAMs, known for their lower carbon footprint compared to ordinary Portland cement (OPC)-based materials.
The research involved partially replacing fly ash (FA) with CSW at replacement levels ranging from 10% to 50%. Both uncalcined and calcined CSW (at temperatures of 400, 600, and 800 °C) were employed to evaluate their effects on the properties of AAMs. The results were striking. “Calcination of CSW significantly enhanced the compressive strength of AAMs compared to uncalcined CSW,” Gan explained. Notably, AAMs prepared with CSW calcined at 800 °C achieved the highest compressive strength of 46.9 MPa.
The study also observed a reduction in water absorption, with AAMs prepared with CSW calcined at 800 °C showing a decrease from 24.0% to 20.5% compared to those using uncalcined CSW. This strength enhancement was attributed to the filler effect of calcined CSW, which densified the microstructure by filling voids.
The implications of this research are far-reaching. By recycling CSW into AAMs, the construction industry can significantly reduce waste and lower its carbon footprint. “This study demonstrates the potential of recycling CSW into AAMs, thereby reducing concrete waste and promoting sustainable construction,” Gan stated.
The commercial impacts for the energy sector are particularly noteworthy. As the demand for sustainable and energy-efficient building materials grows, the adoption of AAMs could lead to substantial reductions in energy consumption and greenhouse gas emissions. This research not only highlights the importance of innovative waste management practices but also paves the way for future developments in sustainable construction materials.
As the construction industry continues to evolve, the findings of this study offer a compelling case for the integration of recycled materials into mainstream construction practices. By embracing these innovations, the industry can move closer to achieving its sustainability goals and contributing to a greener future.