In the dynamic world of construction materials, a groundbreaking study led by Chen-xi Dong from the State Key Laboratory of Geomechanics and Geotechnical Engineering Safety, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, China, has unveiled a novel approach to tackling two pressing issues: hazardous waste management and the development of low-carbon cementitious materials. The research, which was published in ‘Case Studies in Construction Materials’ (Case Studies in Construction Materials), focuses on the use of barium slag (BS), a hazardous industrial by-product, as a supplementary cementitious material (SCM) in calcium aluminate cement (CAC).
Barium slag, a by-product of the barium industry, has long been a challenge for disposal due to its potential toxicity and underuse. However, Dong’s study reveals that its unique thermodynamic history—rapid water quenching at high temperatures—endows it with high reactivity and alkali-activation potential. This makes BS an attractive candidate for partial replacement of CAC, a material widely used in various construction applications.
The findings are compelling. By incorporating BS at a replacement ratio of up to 20%, the study observed a 16% improvement in the fluidity of a CAC slurry. Moreover, the unconfined compressive strengths at 3 days and 90 days increased by 2.5% and 42%, respectively, compared to pure CAC. “This enhancement in mechanical properties is a game-changer for the construction industry,” Dong explains. “It means we can achieve stronger, more durable structures with less environmental impact.”
The study also revealed that the initial and final setting times of the CAC were delayed by 60% and 30%, respectively. This extended workability is particularly beneficial for construction applications requiring longer setting times, such as large-scale infrastructure projects. Microstructural analysis further showed that BS accelerated the hydration process and significantly altered hydration product compositions. The formation of stable hydration products, such as C2ASH8 and AFm phases, reduced the presence of less durable C3AH6, enhancing both early performance and long-term durability.
Environmental safety is another critical aspect of this research. Leaching tests confirmed that Ba²⁺ ions were effectively immobilized within the hydration matrix, ensuring that the CAC–BS composites are environmentally safe. “This is a significant step forward in addressing the environmental challenges posed by industrial by-products,” Dong notes. “By immobilizing these hazardous ions, we can mitigate the environmental risks associated with their disposal.”
The implications of this research are far-reaching. For the energy sector, which often deals with large-scale construction projects, the use of BS in CAC offers a sustainable and cost-effective solution. It not only reduces the environmental footprint but also enhances the performance of construction materials. The study’s findings could pave the way for the development of low-carbon cementitious materials, contributing to the circular economy and environmental sustainability.
As the construction industry continues to evolve, the integration of hazardous industrial by-products like BS into cementitious materials represents a significant advancement. This research not only addresses the immediate challenges of waste management and environmental safety but also opens new avenues for innovation in the field. By promoting resource-efficient construction materials, Dong’s study aligns with global efforts to achieve a more sustainable and circular economy.