In the quest for sustainable and efficient construction materials, researchers have long explored the potential of alkali-activated slag binders. A recent study, led by Cengiz Kızılırmak from the Institute of Natural and Applied Sciences at Dokuz Eylul University in Izmir, Türkiye, has shed new light on enhancing the mechanical properties of sodium carbonate-activated slag-based binders. Published in ‘Materials Research Express’ (which translates to ‘Materials Research Express’ in English), this research could have significant implications for the energy sector and construction industry.
The study focuses on accelerating the slow early reaction process of sodium carbonate (SC) activated slag (GGBFS) mixtures by adding small amounts of calcium oxide (quicklime, CaO) or calcium hydroxide (hydrated lime, Ca(OH)₂). This innovation addresses a critical challenge in the use of SC-activated slag (SCAS) binders: their slow setting time and initially low compressive strength.
“Our findings demonstrate that the addition of quicklime or hydrated lime can significantly improve the early and ultimate compressive strength of SCAS binders,” Kızılırmak explained. The research revealed that with the right proportion of quicklime or hydrated lime, SCAS mixtures can achieve reasonable compressive strength—up to about 8 MPa at 2 days and 45 MPa at 28 days—and more practical setting times ranging from 25 to 240 minutes.
The study also explored the effects of steam curing on these enhanced SCAS mixtures. Remarkably, steam curing at 50 °C after a 24-hour pre-curing period boosted the early-age compressive strength to 28 MPa at just 2 days. However, temperatures above 50 °C were found to reduce the ultimate compressive strength, highlighting the importance of optimizing curing conditions.
For the construction and energy sectors, these findings could translate into more efficient and cost-effective building materials. The ability to accelerate the setting time and improve early strength of SCAS binders could lead to faster construction processes and reduced energy consumption in curing. This is particularly relevant for large-scale infrastructure projects where time and energy efficiency are critical.
Kızılırmak’s research also identified the optimal lime content for both quicklime and hydrated lime to be between 3% and 4%. This precision is crucial for practical applications, ensuring that the enhancements are both effective and economically viable.
As the construction industry continues to seek sustainable and high-performance materials, this study offers a promising avenue for innovation. The insights gained from Kızılırmak’s work could pave the way for new standards in the use of alkali-activated slag binders, potentially reshaping the future of construction materials and practices.
In the broader context, this research underscores the importance of interdisciplinary collaboration and the continuous pursuit of scientific advancements. As Kızılırmak noted, “The potential applications of these findings are vast, and we are excited to see how they will influence the industry moving forward.”
With the publication of this study in ‘Materials Research Express’, the construction and energy sectors have a new tool in their arsenal to build more efficiently and sustainably. The journey towards optimizing SCAS binders is just beginning, and the future looks promising.