In the heart of Shanghai, researchers are turning a global environmental challenge into an opportunity for sustainable construction. Li Shao, a leading expert from the School of Environment and Architecture at the University of Shanghai for Science and Technology, has pioneered a novel approach to recycling high-water-content waste slurry, transforming it into a valuable construction material while simultaneously reducing carbon emissions.
The problem is immense: global urbanization has led to a massive generation of waste slurry, posing serious environmental challenges. Traditional treatment methods are often costly and unsustainable, while conventional cement-based foamed lightweight soils typically exhibit low strength and limited CO2 sequestration. Shao’s research, published in the journal ‘Buildings’ (translated as ‘建筑’ in Chinese), offers a groundbreaking solution.
Shao and her team have developed a unique stabilization pathway by integrating a MgO–mineral powder–carbide slag composite binder with CO2 foaming–carbonation. This innovative process enables simultaneous slurry lightweighting, strength enhancement, and CO2 fixation. “We are not just treating waste; we are creating a new, value-added construction material,” Shao explained.
The research involved a series of laboratory tests to evaluate the flowability, density, compressive strength, and deformation characteristics of the carbonated lightweight stabilized slurry. Microstructural analyses, including Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD), revealed the formation of carbonate phases and pore structures. The results were promising: MgO content strongly promoted carbonation, leading to denser microstructures and higher strength. Mineral powder and carbide slag optimized workability and pore stability.
Orthogonal testing indicated that a mix with 25% mineral powder, 12.5% MgO, and 7.5% carbide slag achieved the best performance, with unconfined compressive strength up to 0.48 MPa after carbonation. Compared with conventional cement- or GGBS-based foamed lightweight soils, the proposed system exhibits superior strength development, improved pore stability, and enhanced CO2 sequestration potential.
The implications for the energy and construction sectors are significant. This technology not only provides a sustainable solution for waste slurry management but also contributes to carbon reduction targets. “This is a win-win situation,” Shao noted. “We are reducing waste, improving construction materials, and lowering carbon emissions all at once.”
The research opens new avenues for integrating CO2 mineralization into geotechnical engineering practice. As the world grapples with the dual challenges of waste management and climate change, innovations like Shao’s offer a beacon of hope. The study demonstrates the feasibility of recycling high-water-content waste slurry into value-added construction materials, paving the way for a more sustainable future.
In the ever-evolving landscape of construction technology, this research stands out as a testament to the power of innovation and the potential for turning environmental challenges into opportunities. As the industry continues to seek sustainable solutions, Shao’s work serves as a guiding light, illuminating the path forward.